Allison

Allison 3000 & 4000 Gen 4 Fault Code: P2789 Clutch Adaptive Learning at Limit

0 comentarios

DIAGNOSTIC RESPONSE:
None

CIRCUIT DESCRIPTION:
The Transmission Health Monitor is (TM) is part of the 4th Generation Control System Prognostics package. This feature monitors adaptively learned clutch volume changes. These volumes are correlated to calculated free running clearances for each of the transmission clutches C1, C2, C3, C4, and C5. The adaptive information is compared with the baseline volumes and clearances established by the function when the clutches were new or just after a function reset was performed following a clutch system repair.

If the predicted clutch life left for C1 through C5 is 6% or less, or if the predicted free running clearance of any clutch exceeds its maximum value, then the TRANS SERVICE indicator (wrench icon on Allison shift selector) illuminates informing the operator that there is a need for service. The wrench icon (and TRANS SERVICE indicator, if separate) stays illuminated during vehicle operation until clutch system service is performed and the TM function can reset itself with the new predicted values. The OEM may also be used to reset the TM function in the Action Request screen.

If the TM function is not reset within several ignition cycles of illuminating the TRANS SERVICE indicator, then a CHECK TRANS indicator illuminates indicating P2789. The TM automatically resets itself if the function detects that the values for remaining clutch life or predicted free running clearance are back within specification.

CONDITIONS FOR RUNNING THE DTC:
Enabled by calibration

CONDITIONS FOR SETTING THE DTC:
This DTC sets when percent clutch life remaining is less than 6% and continues to stay under 16% for the next 100 hours of TCM run time.

ACTION TAKEN WHEN THE DTC SETS:
1. The TCM illuminates the CHECK TRANS light.
2. The DTC is stored in the TCM history.

CONDITIONS FOR CLEARING THE DTC/CHECK TRANS LIGHT:
1. This DTC goes inactive when percent clutch life remaining is predicted to be more than 16%.
2. Use the diagnostic tool to Reset Transmission Health Indicator by specific clutch(es) through the Action Request screen. The DTC may also be cleared from TCM history using the diagnostic tool.

DIAGNOSTIC AIDS:
Refer to OEM 4th Generation Control System Operation and Prognostics Package and Features for important information about Oil Life Monitor (OM), Filter Life Monitor (FM), and Transmission Health Monitor (TM). These sections discuss prognostics principles of operation, feature requirements, type of maintenance alerts, reports, and processes to reset features or change fluid type (available January 2010 and later TCM software) using both the diagnostic tool or an OEM-supplied MY09 and later shift selector.

Other factors besides clutch wear may cause this DTC such as:
1. OEM solenoid wiring issue, e.g., high resistance wires, poor pin crimps expanded terminal, poor power and grounds.
2. Defective solenoid.
3. Sticking valve.
4. Worn valve body.
5. Weak trim springs.
6. Low main pressure.
7. Low control main pressure.
8. Leak to sump of exhaust backfill.
9. Leaking piston seal.
10. Defective TCM.

NOTE: When transmission clutches are replaced, always select “Reset Adaptive Shift Parameters” and “Reset Prognostics Information” on the diagnostic tool. This will allow access to “Reset Transmission Health Monitor” and “Reset Oil Life Monitor” from the “Action Request” menu. Refer to Fluid Check Procedures, Prognostics Package and Features, First Steps and Tips for Troubleshooting, and the OEM Technician’s Library for additional information.

NOTE: Do not base transmission removal solely because this DTC is active or that a Trans Health report comes back red on a clutch. Instead, perform an inspection and function check of the transmission in chassis, if possible, e.g., clutch tests, pressure checks, and stall check to look for slipping clutch, etc. If the transmission function checks, such as fluid filter check, fluid condition check, shift quality check, and clutch pressure check are all normal, then do not remove the transmission from the vehicle. Instead, continue to monitor the transmission for issues and look for other causes for the high fill volumes mentioned in Diagnostic Aids for this DTC.

NOTE: Refer to General Troubleshooting of Performance Complaints for indicator lamp issues. OEM action requests and lamp tests may be used to check functionality of SERVICE TRANS indicator (wrench icon).


Leer más →

Allison 3000 & 4000 Gen 4 Fault Code: P278A Kickdown Input Failed ON

0 comentarios

DIAGNOSTIC RESPONSE:
Inhibit kickdown operation

CIRCUIT DESCRIPTION:
The Transmission Control Module (TCM) can be calibrated to receive an acceleration pedal kickdown input from either an analog input wire or a digital datalink message. When the operator activates the kickdown feature in the Economy Mode, the TCM uses Performance shift points. A momentary, normally open switch attached to the throttle pedal typically generates the kickdown input signal. The switch usually provides a detente feel when full-throttle is achieved. Some OEMs may opt to send a kickdown datalink message when a threshold for accelerator pedal percentage has been reached (e.g., 95%), and not implement the momentary switch in the circuit. However, on vehicles with the switch, the kickdown function is activated when the operator steps through the detente.

For implementation of the kickdown feature via datalink with a momentary switch, the switch input is sent to the controller responsible to send a kickdown active message over the datalink to the 4th Generation TCM.

The SAE J1939 Controller Area Network (CAN) is the preferred digital datalink. The TCM communicates with the Engine Control Module (ECM) and other controllers by exchanging standardized digital messages over SAE J1939. The Physical network consists of a two-wire twisted pair, two 120 Ω termination resistors, and in most cases a third shielded wire. A 120 Ω termination resistor is located at each end of the network Vehicle OEMs may choose to install external termination resistors or use internal termination resistors built into many SAE J1939 electronic modules, including the TCM and shift selector. Refer to the OEM Technician’s Library for additional information.

CONDITIONS FOR RUNNING THE DTC:
1. TCM initialized normally and engine speed is above 200 rpm.
2. For vehicles requiring analog kickdown input, the proper kickdown input function must be enabled.
3. For vehicles requiring a datalink kickdown message, an acceptable OEM source address must be autodetected or enabled in calibration.

CONDITIONS FOR SETTING THE DTC:
DTC P278A sets if the TCM is calibrated to receive the kickdown input signal and both of the following conditions are met:
1. Throttle percentage is less than 20 percent.
2. The kickdown input signal is ON for more than 5 seconds.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P278A is active, the following conditions occur:
1. The CHECK TRANS light does not illuminate.
2. DTC is stored in TCM history.
3. TCM inhibits kickdown operation.

CONDITIONS FOR CLEARING THE DTC/CHECK TRANS LIGHT:
Use the diagnostic tool to clear the DTC from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without failure.

DIAGNOSTIC AIDS:
When analog input wires are used, the kickdown function is active when a switch is closed to complete the circuit between wire 122 and signal return wire 103. If a datalink is used, the TCM receives accelerator pedal kickdown input as part of a SAE J1939 message parameters PGN 61443, Electronic Engine Controller 2 (EEC2).

DTC P278A indicates the TCM has detected a kickdown input signal for more than 5 seconds with less than full throttle conditions. The code can be caused by:
1. Chassis wiring shorted to ground, high resistance or open.
2. Faulty connections to the accelerator pedal kickdown switch.
3. A faulty accelerator pedal kickdown switch.
4. Another controller improperly broadcasting kickdown signal on the data link when throttle conditions are not met.
5. A faulty TCM.
6. SAE J1939 Kickdown status can be read on the diagnostic tool. Monitor data link communications using Data Bus Viewer.
7. A faulty accelerator pedal.

If DTC is still active, review applicable information in the OEM Technician’s Library, Control System and Transmission Specifications, and other related information.

Leer más →

Allison 3000 & 4000 Gen 4 Fault Code: P2793 Gear Shift Direction Circuit

0 comentarios

DIAGNOSTIC RESPONSE:
Ignores PWM input from shift selector

CIRCUIT DESCRIPTION:
The OEM 4th Generation Controls shift selectors communicates with the Transmission Control Module (TCM) by exchanging standardized digital messages over the SAE J1939 Controller Area Network (CAN). The shift selectors are also equipped with a single wire backup to the SAE J1939 CAN datalink. The OEM 4th Generation shift selectors transmit directional information (Forward, Neutral, and Reverse) in form of an analog Pulse-Width Modulated (PWM) signal via wire 134 to the TCM. The shift selector switches an internal driver ON and OFF to vary the duty cycle of the voltage on wire 134. When the driver in the shift selector is ON, the voltage on wire 134 is pulled to ground. When the driver is OFF, the driver’s output is open and the voltage on wire 134 is high. Since duty cycle is measured when voltage is high, the driver’s OFF-time determines the duty cycle. For example, if wire 134 duty cycle is 15 percent, the shift selector driver is ON (pulled low) 85 percent of the time and OFF (open) 15 percent of the time.

CONDITONS FOR RUNNING THE DTC
After TCM initializes normally and the engine speed is above 200 rpm for more than 5 seconds.

CONDITIONS FOR SETTING THE DTC:
When the duty cycle is invalid for more than 1 second.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P2793 is active, the following conditions occur:
1. The DTC is stored in the TCM history.
2. The TCM illuminates the CHECK TRANS light.
3. The TCM ignores PWM signal from shift selector.
4. If CAN signal is also lost, the TCM locks in last valid direction.

CONDITIONS FOR CLEANING THE DTC/CHECK TRANS LIGHT
The diagnostic tool may be used to clear from DTC from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.

DIAGNOSTIC AIDS:
This DTC may be caused by:
1. Short to power or short to another wire in W134.
2. High resistance or open in W134.
3. Poor vehicle grounds.
4. Unlocked connectors, expanded terminals, poor pin crimps or unlocked pins causing high resistance or open circuit.
5. Unlocked connectors, unlocked pins, causing shorts in connectors.
6. TCM ground is at different voltage potential than the ground of the OEM voltage source responsible for shift selector.
7. Defective TCM.
8. Defective shift selector.
9. The PWM signal characteristics are listed below:

Primary Shift Selector 977 Hz 10 Hz (When Active):
1. Unknown: 15% ± 2% Duty Cycle
2. Park: 30% ± 2% Duty Cycle
3. Reverse: 45% ± 2% Duty Cycle
4. Neutral: 60% ± 2% Duty Cycle
5. Forward: 75% ± 2% Duty Cycle
6. Error: 90% ± 2% Duty Cycle

Secondary Shift Selector 871 Hz 10 Hz (When Active):
1. Unknown: 15% ± 2% Duty Cycle
2. Park: 30% ± 2% Duty Cycle
3. Reverse: 45% ± 2% Duty Cycle
4. Neutral: 60% ± 2% Duty Cycle
5. Forward: 75% ± 2% Duty Cycle
6. Error: 90% ± 2% Duty Cycle

Leer más →

Allison 3000 & 4000 Gen 4 Fault Code: P2808 Pressure Control Solenoid 6 (PCS6) Stuck Off

0 comentarios

DIAGNOSTIC RESPONSE:
DNS, RPR

CIRCUIT DESCRIPTION:
The Transmission Control Module (TCM) uses input from the turbine speed and output speed sensors to determine the current commanded for steady-state gear ratio. The TCM then compares the known gear ratio to the calculated gear ratio for the current range.

This DTC test determines if the on-coming clutch controlled by Pressure Control Solenoid 6 (PCS6) engages during a forward range shift. PCS6 controls the C6 clutch for Low range in 3700/4700/4800 transmission models. PCS6 controls C6 clutch for Reverse 2 in the 4700/4800 model.

CONDITIONS FOR RUNNING THE DTC:
1. Hydraulic system is pressurized.
2. Hydraulic default condition not present.
3. Output speed is above 125 rpm.
4. Turbine speed above 60 rpm.
5. Engine initialization or shutdown is not in process.

CONDITIONS FOR SETTING THE DTC:
DTC P2808 sets when the TCM detects the on-coming clutch did not maintain engagement after 2 seconds during the range shifts that require PCS6 to control C6 clutch.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P2808 is active, the following conditions will occur:
1. If DTC goes active while making a forward range shift (e.g., 1-2) ,the transmission returns to the previous range. If DTC goes active during a shift to reverse or neutral, the transmission shifts to neutral. Once shifting is complete, the attained range is locked in range.
2. While diagnostics response is active, the TCM ignores shift selector inputs.
3. The CHECK TRANS light illuminates.
4. DTC is stored in the TCM history.
5. TCM inhibits TCC engagement.
6. TCM freezes shift adapts (DNA).

CONDITIONS FOR CLEARING THE DTC/CHECK TRANS LIGHT:
Use the diagnostic tool to clear the DTC from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.

DIAGNOSTIC AIDS:
NOTE: This DTC requires Clutch Test using the diagnostic tool to detect clutch slip during a partial stall and also to pressurize clutches for measurement without needing to drive the vehicle. Note that main pressure and clutch pressures are reduced when the Main Mod Solenoid is energized. Low commanded Main Mod solenoid pressures shown in Data Monitor correlate to reduced main pressure and clutch pressures. Main pressure is reduced by Main Mod in N (Neutral), 1 (First Range), and 2 (Second Range) when engine speed is below 1500 rpm. High Main Mod commanded pressures correlate to no reduction in main pressure and clutch pressures. Refer to First Steps and Tips for Troubleshooting and OEM Technician’s Library for more information about the action requests for Clutch Test, Full Main Pressure Test, and also the procedure for Stall Testing.

DTC P2808 may be caused by:
1. Output speed sensor signal circuit issues.
2. Turbine speed sensor signal circuit issues.
3. Low clutch pressures, main pressure, or control main pressure.
4. Control module issues like stuck/sticky valves, mechanically defective solenoids, broken springs, damaged valve bores, plugged suction filter, damaged gaskets, excessive leaks to exhaust, etc.
5. Transmission issues such as damaged output speed sensor wheel slot, worn and/or damaged seals or seal rings, dislocated snap rings worn clutch packs, rotating drum damage (affecting turbine speed pickup), debris, excessive hydraulic circuit leaks to exhaust or other hydraulic circuits.

NOTE: Damage to the output speed sensor wheel slot is an indication the driveline does not meet ATI specifications. Correct all driveline issues before putting transmission back in service.

6. Issue with TCM.
7. A high resistance circuit in Shift Solenoid 1 (SSI) low side solenoid wire (W151) may cause this code. There may be a P0973 in history with this code. SS1 strokes he C2 latch valve when energized. A high resistance connection may not fully energize the SS1 in order to stroke the C2 latch. Check for expanded terminals, broken/loose connectors, loose pin crimps, or damaged W151 in chassis harness. Check condition of wire harness in control valve module and the SS1 resistance if needed.
8. PCS6 controls the C6 clutch. However, this code may also occur when any other clutch did not maintain engagement while C6 is commanded.

Leer más →

Allison 3000 & 4000 Gen 4 Fault Code: P2809 Pressure Control Solenoid 6 (PCS6) Stuck On

0 comentarios

DIAGNOSTIC RESPONSE:
DNS, RPR

CIRCUIT DESCRIPTION:
The Transmission Control Module (TCM) uses input from the turbine speed and output speed sensors to determine the current commanded for steady-state gear ratio. The TCM then compares the known gear ratio to the calculated gear ratio for the current range.

This DTC test determines if the off-going clutch controlled by Pressure Control Solenoid 6 (PCS6) remains engaged during a forward range shift. PCS6 controls the C6 clutch for Low Gear in 3700/4700/4800 transmission models. PCS6 controls C6 clutch for Reverse 2 in the 4700/4800 model.

CONDITIONS FOR RUNNING THE DTC:
1. Hydraulic system is pressurized.
2. Hydraulic default condition not present.
3. Output speed is 200 rpm or higher.
4. Turbine speed is 200 rpm or higher.
5. Engine initialization or shutdown is not in process.

CONDITIONS FOR SETTING THE DTC:
DTC P2809 sets when the TCM detects the off-going clutch did not fully release after 2 seconds during the range shifts that require PCS6 to control C6 clutch.

ACTION TAKEN WHEN THE DTC SETS:
When the DTC P2809 is active, the following conditions will occur:
1. If DTC goes active while making a forward range shift (e.g., 1-2), the transmission returns to the previous range. If DTC goes active during a shift to reverse or neutral, the transmission shifts to neutral . Once shifting is complete, the attained range is locked in range.
2. While diagnostic response is active, the TCM ignores shift selector inputs.
3. The CHECK TRANS light illuminates.
4. DTC is stored in the TCM history.
5. TCM inhibits TCC engagement.
6. TCM freezes shift adapts (DNA).

CONDITIONS FOR CLEARING THE DTC/CHECK TRANS LIGHT:
Use the diagnostic tool to clear the DTC from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.

DIAGNOSTIC AIDS:
NOTE: This DTC requires Clutch Test using diagnostic tool to detect clutch slip during a partial stall and also to pressurize clutches for measurement without needing to drive the vehicle. Note that main pressure and clutch pressures are reduced when the Main Mod Solenoid is energized. Low commanded Main Mod solenoid pressures shown in Data Monitor correlate to reduced main pressure and clutch pressures. Main pressure is reduced by Main Mod in N (Neutral), 1 (First Range), and 2 (Second Range) when engine speed is below 1500 rpm. Higher Main Mod commanded pressures correlate to no reduction in main pressure and clutch pressures. Refer to First Steps and Tips for Troubleshooting and the OEM Technician’s Library for more information about the actions requests for Clutch Test, Full Main Pressure Test, and also the procedure for Stall Testing.

DTC P2809 may be cause by:
1. Output speed sensor signal circuit issues.
2. Turbine speed sensor signal circuit issues.
3. Low clutch pressures, main pressure, or control main pressure.
4. Control module issues like stuck/sticky valves, mechanically defective solenoids, broken springs, damaged valve bores, plugged suction filter, damaged gaskets, excessive leaks to exhaust, etc.
5. Transmission issues such as damaged output speed sensor wheel slot, worn and/or damaged seals or seal rings, dislocated snap rings, worn clutch packs, rotating drum damage (affecting turbine speed pickup), debris, excessive hydraulic circuit leaks to exhaust or other hydraulic circuits.

NOTE: Damage to the output speed sensor wheel slot is an indication the driveline does not meet ATI specifications. Correct all driveline issues before putting transmission back in service.

6. Issue with TCM.
7. A high resistance circuit in Shift Solenoid 1 (SS1) low side solenoid wire (W151) may cause this code. There may be a P0973 in history with this code. SS1 strokes the C2 latch valve when energized. A high resistance connection may not fully energize the SS1 in order to stoke the C2 latch. Check for expanded terminals, broken/loose connectors, loose pin crimps, or damaged W151 in chassis harness. Check condition of wire harness in control valve module and the SS1 resistance if needed.

8. PCS26 controls the C6 clutch . However, this code may also occur for any off-going clutch issue while C6 is commanded.


Leer más →

Allison 3000 & 4000 Gen 4 Fault Code: P2812 Pressure Control Solenoid 6 (PCS6) Control Circuit Open

0 comentarios

DIAGNOSTIC RESPONSE:
DNS, SOL OFF (hydraulic default)

CIRCUIT DESCRIPTION:
Pressure Control Solenoid 6 (PCS6) is a normally closed solenoid used to apply to C6 clutch in Low (L) range (7-speed models only). The Transmission Control Module (TCM) commands the solenoid ON to produce hydraulic pressure in the clutch apply circuit. When PCS6 is commanded OFF, the clutch pressure is released. The TCM sends control current to PCS6 from High Side Driver 1 (HSD1) via wire 111. HSD1 is continuously ON unless the TCM detects a fault condition. The TCM regulates the amount of current to PCS6 by switching PCS6 low side driver ON and OFF. W178 completes the circuit between PCS6 and its low side driver. DTC P2812 indicates that the TCM has detected an open condition in the PCS6 electrical circuit. The open condition may exist in the high side (wire 111) or low side (wire 178).

CONDITIONS FOR RUNNING THE DTC:
TCM initialized normally and engine speed above 200 rpm.

CONDITIONS FOR SETTING THE DTC:
This DTC sets when the TCM detects PCS6 low side driver has been detected in a failed open state.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P2812 is active:
1. If failure occurs while in a forward range, then shift to another forward range. If failure occurs while in Neutral (N), the transmission remains in Neutral (N). If failure occurs while in Reverse (R), transmission remains in Reverse (R) or shifts to Neutral (N). Once range is attained, transmission will be locked in range. There is no response to shift selector requests.
2. DTC is stored in the TCM history.
3. The CHECK TRANS light illuminates.
4. The TCM freezes shift adapts (DNA).

CONDITIONS FOR CLEARING THE DTC:
Use the diagnostic tool to clear the DTC from the TCM history. The TCM automatically clears the DTC from the TCM history if he vehicle completes 40 warm-up cycles without failure.

DIAGNOSTIC AIDS:
DTC P2812 can be caused by:
1. PCS6 issues such as:
– W178 open circuit in chassis harness.
– W178 (terminal 7 of 20-way) open circuit in internal transmission harness.
– PCS6 defective.
2. Unlocked connectors, expanded terminals, poor pin crimps or unlocked pins causing high resistance or open circuit.
3. Defective TCM.

Review applicable information in Control System and Transmission Specifications to find additional circuit specifications, system and connector diagrams, and troubleshooting tips.

Leer más →

Allison 3000 & 4000 Gen 4 Fault Code: P2814 Pressure Control Solenoid 6 (PCS6) Control Circuit Low

0 comentarios

DIAGNOSTIC RESPONSE:
DNS, SOL OFF (hydraulic default)

CIRCUIT DESCRIPTION:
Pressure Control Solenoid 6 (PCS6) is a normally closed solenoid used to apply the C6 clutch in Low (L) range (7-speed models only). The Transmission Control Module (TCM) commands the solenoid ON to produce hydraulic pressure in the clutch apply circuit. When PCS6 is commanded OFF, the clutch pressure is released. The TCM sends control current to PCS6 from High Side Driver 1 (HSD1) via wire 111. HSD1 is continuously ON unless the TCM detects a fault condition. The TCM regulates the amount of current to PCS6 by switching PCS6 low side driver ON and OFF. Wire 178 completes the circuit between PCS6 and its low side driver. DTC P2814 indicates that the TCM has detected a failed low condition in the PCS6 electrical circuit. The condition may exist in the high side (wire 111) or low side (wire 178).

CONDITIONS FOR RUNNING THE DTC:
TCM initialized normally and engine speed above 200 rpm.

CONDITIONS FOR SETTING THE DTC:
This DTC sets when the TCM detects PCS6 low side driver has been detected in a failed low state.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P2814 is active:
1. If failure occurs while in a forward range, then shift to another forward range. If failure occurs while in Neutral (N), the transmission remains in Neutral (N). If failure occurs while in Reverse (R), transmission remains in Reverse (R) or shifts to Neutral (N). Once range is attained, transmission will be locked in range. There is no response to shift selector requests.
2. DTC is stored in the TCM history.
3. The CHECK TRANS light illuminates.
4. The TCM freezes shift adapts (DNA).

CONDITIONS FOR CLEARING THE DTC:
Use the diagnostic tool to clear the DTC from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without failures.

DIAGNOSTIC AIDS:
DTC P2814 can be caused by:
1. PCS6 issues such as:
– W178 shorted to another wire or ground in chassis harness.
– W178 (terminal 7 of 20-way) shorted to another wire or ground in internal transmission harness.
– PCS6 defective.
2. Broken on defective connector assemblies allowing pushed back pins to short together.
3. Unlocked connectors, missing seal plugs allowing moisture in connectors.
4. Defective TCM.

Review applicable information in Control System and Transmission Specifications to find additional circuit specifications, system and connector diagrams, and troubleshooting tips.

Leer más →

Allison 3000 & 4000 Gen 4 Fault Code: P2815 Pressure Control Solenoid 6 (PCS6) Control Circuit High

0 comentarios

DIAGNOSTIC RESPONSE:
DNS, SOL OFF (hydraulic default)

CIRCUIT DESCRIPTION:
Pressure Control Solenoid 6 (PCS6) is a normally closed solenoid used to apply the C6 clutch in Low (L) range (7-speed models only). The Transmission Control Module (TCM) commands the solenoid ON to produce hydraulic pressure in the clutch apply circuit. When PCS6 is commanded OFF, the clutch pressure is released. The TCM sends control current to PCS6 from High Side Driver 1 (HSD1) via wire 111. HSD1 is continuously ON unless the TCM detects a fault condition. The TCM regulates the amount of current to PCS6 by switching PCS6 low side driver ON and OFF. Wire 178 completes the circuit between PCS6 and its low side driver. DTC P2815 indicates that the TCM has detected a failed high condition in the PCS6 electrical circuit.

CONDITIONS FOR RUNNING THE DTC:
TCM initialized normally and engine speed above 200 rpm.

CONDITIONS FOR SETTING THE DTC:
This DTC sets when the TCM detects PCS6 low side driver has been detected in a failed high state.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P2815 is active:
1. If failure occurs while in a forward range, then shift to another forward range. If failure occurs while in Neutral (N), the transmission remain in Neutral (N). If failure occurs while in Reverse (R), the transmission remains in Reverse (R) or shifts to Neutral (N). Once range is attained, the transmission will be locked in range. There is no response to shift selector requests.
2. DTC is stored in the TCM history.
3. The TCM inhibits Torque Converter Clutch (TCC) engagement.
4. The CHECK TRANS light illuminates.
5. The TCM freezes shift adapts (DAN).

CONDITIONS FOR CLEARING THE DTC:
Use the diagnostic tool l to clear the DTC from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without failure.

DIAGNOSTIC AIDS:
DTC P2815 can be caused by:
1. PCS6 issues such as:
– W178 shorted to another wire in chassis harness.
– W178 (terminal 7 of 20-way) shorted to another wire in internal transmission harness.
– PCS6 defective.
2. Broken or defective connector assemblies allowing pushed back pins to short together.
3. Unlocked connectors, missing seal plugs allowing moisture in connectors.
4. Defective TCM.

Review applicable information in Control System and Transmission Specifications to find additional circuit specifications, system and connector diagrams, and troubleshooting tips.

Leer más →

Allison 3000 & 4000 Gen 4 Fault Code: U0001 Hi Speed CAN2 Bus Reset Counter Overrun (CAN2/IESCAN)

0 comentarios

DIAGNOSTIC RESPONSE:
Use default values, inhibit SEM

CIRCUIT DESCRIPTION:
Beginning MY07, OEM 4th Generation Controls Transmission Control Modules (TCMs) were capable of communicating with some Mercedes engines via the IESCAN on CAN2. Beginning with January 2011 software, TCMs were capable of communicating on high -speed SAE J1939 (500 kbps) on CAN2. The TCM uses the high-speed Controller Area Network 2 (CAN2) chip to exchange standardized messages with the engine controller and other vehicle systems. The IESCAN and SAE J1939 CAN2 physical network consists of two-wire twisted pair, two 120 Ohm resistors and, in most cases, a third shield wire and CAN2 capable controllers. A 120 Ohm termination resistor is located at each end of the network. Vehicle OEMs may choose to install external termination resistors or use internal termination resistors built into many electronic modules. CAN2 capable modules include the TCM and shift selector. Refer to the OEM Technician’s Library for additional information.

NOTE: Some applications may use the Type 2 (Green), SAE J1939-13, 9-Pin service tool connector for CAN-2 installations instead of the SAE J2284 trapezoidal connector. Refer to the OEM Technician’s Library for wiring information.

CONDITIONS FOR RUNNING THE DTC:
After TCM initializes normally and engine speed is above 200 rpm for more than 5 seconds, this DTC test will run at 0.1 second intervals.

CONDITIONS FOR SETTING THE DTC:
DTC U0001 sets when the TCM detects no communication on the CAN2 datalink for 0.2 seconds or more.

ACTION TAKEN WHEN THE DTC SETS:
1. The TCM does not illuminate the CHECK TRANS light.
2. DTC is stored in TCM history.
3. SEM operation is not active, if applicable.
4. Default values are substituted for missing data, e.g., engine throttle percentage, engine torque, engine coolant temperature.
5. SAE J1939 Shift Selector input (if on CAN2 ) is lost (fails over to W134 directional signal).
6. The TCM freezes shift adapts (DNA).

CONDITIONS FOR CLEARING THE DTC/CHECK TRANS LIGHT:
Use the diagnostic tool to clear the DTC from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.

DIAGNOSTIC AIDS:
1. DTC U0001 indicates that a CAN2 bus hardware error has occurred.
This code may be caused by:
– Miswired or defective OEM controllers, OEM components, or OEM circuits attached to CAN2.
– Defective TCM.
– Defective shift selector.
2. Vehicle manufacturers may use the following terminal pairs for CAN2 high and low wires:
– Terminals 6 and 27.
– Terminals 66 and 47.
– Both terminals 6 and 27 and terminals 66 and 47 are wired in a pass-through setup.
3. Vehicle manufacturers may wire the TCM into the CAN2 backbone in three different ways:
– The TCM may be on its own stub as in traditional CAN backbones.
– The TCM may be wired in a pass-through configuration such that the CAN high and low wires are
connected to two separate pin pairs in the TCM 80-way connector. Datalink messages pass-through
but can still be viewed by the TCM.
– The TCM may represent one end of the backbone. Typically, the internal resistor in the TCM will be
used in this setup.
4. An active DTC U0001 may prevent the diagnostic tool from communicating with the TCM. The J-47276 TCM Reflash Harness may be used to confirm that the TCM is operational. Connect the TCM Reflash Harness to the TCM and leave the OEM harness disconnected. Provide input power from the J-42455-A Load Box.
5. CAN1 and CAN2 devices must not be interconnected because they are not compatible with each other. CAN1 operates at 250 kbps data rate and CAN2 operates at 500 kbps data rate.
6. The diagnostic tool will not communicate on CAN2 without appropriate translator, cables, and translator drivers. Refer to the diagnostic tool Help menu and User Guide for more information about service tool connection requirements for CAN2.
7. For proper datalink communications, it is necessary to have two 120 Ω resistors installed in parallel across the CAN2 High and CAN2 Low terminals. Resistance across CAN2 High and CAN2 Low should measure 60 Ω when wired correctly.

Review applicable information in the OEM Technician’s Library, General Troubleshooting of Performance Complaints – Shift Selector Issues, Control System and Transmission Specifications, and other related information.


Leer más →

Allison 3000 & 4000 Gen 4 Fault Code: U0010 CAN1/SAE J1939 Bus Reset Counter Overrun

0 comentarios

DIAGNOSTIC RESPONSE:
Use default values, inhibit SEM

CIRCUIT DESCRIPTION:
In the OEM 4th Generation Controls, the preferred digital datalink is the SAE J1939 Controller Area Network (CAN). The Transmission Control Module (TCM) communicates with the engine control module and other controllers by exchanging standardized digital messages over SAE J1939. The physical network consists of two-wire twisted pair, two 120 Ω termination resistors and, in more cases, a third shield wire. A 120 Ω termination resistor is located at each end of the network. Vehicle OEMs may choose to install external termination resistors or use internal termination resistors built into many SAE J1939 electronic modules, including the TCM and shift selector. Refer to the OEM Technician’s Library for additional information.

CONDITIONS FOR RUNNING THE DTC:
After TCM initializes normally and engine speed is above 200 rpm for more than 5 seconds, this DTC test will run at 0.1 second intervals.

CONDITIONS FOR SETTING THE DTC:
DTC U0010 sets when the TCM detects no communication on the CAN1 backbone harness for 3 seconds or more.

ACTION TAKEN WHEN THE DTC SETS:
1. The TCM does not illuminate the CHECK TRANS light.
2. DTC is stored in TCM history.
3. SEM operation is not active, if applicable.
4. Default values are substituted for missing data, e.g., engine throttle percentage, engine torque, engine coolant temperature.
5. SAE J1939 Shift Selector input on CAN1 is low (W134 directional signal failure).
6. The TCM freezes shift adapts (DNA).

CONDITIONS FOR CLEARING THE DTC/CHECK TRANS LIGHT:
Use the diagnostic tool to clear the DTC from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.

DIAGNOSTIC AIDS:
1. DTC U0010 indicates that a CAN1 bus hardware error has occurred.
This code may be caused by:
– Miswired or defective OEM controllers, OEM components, or OEM circuits attached to CAN1.
– Defective TCM.
– Defective shift selector.
2. Vehicle manufacturers may use the following terminal pairs for CAN1 high and low wires:
– Terminals 8 and 28.
– Terminals 48 and 68.
– Both terminals 8 and 28 and terminals 48 and 68 are wired in a pass-through setup.
3. Vehicle manufacturers may wire the TCM into the CAN1 backbone in three different ways:
– The TCM may be on its own stub as in traditional CAN backbones.
– The TCM may be wired in a pass-through configuration such that the CAN high and low wires are
connected to two separate pin pairs in the TCM 80-way connector. Datalink messages pass-through
but can still be viewed by the TCM.
– The TCM may represent one end of the backbone. Typically, the internal resistor in the TCM will be
used in this setup.
4. An active DTC U0010 may prevent the diagnostic tool from communicating with the TCM. The J-47276 TCM Reflash Harness may be used to confirm that the TCM is operational. Connect the TCM Reflash Harness to the TCM and leave the OEM harness disconnected. Provide input power from the J-42455-A Load Box.
5. CAN1 and CAN2 devices must not be interconnected because they are not compatible with each other. CAN1 operates at 250 kbps data rate and CAN2 operates at 500 kbps data rate.
6. For proper datalink communications, it is necessary to have two 120 Ω resistors installed in parallel across the CAN1 High and CAN1 Low terminals. Resistance across CAN1 High and CAN1 Low should measure 60 Ω when wired correctly.

Review applicable information in the OEM Technician’s Library, General Troubleshooting of Performance Complaints – Shift Selector Issues, Control System and Transmission Specifications, and other related information.

Leer más →

← Anterior 1 … 31 32 33 34 35 … 53 Siguiente →