Allison

DIAGNOSTIC RESPONSE:
DNS, Lock in current range

CIRCUIT DESCRIPTION:
The speed sensors are variable reluctance devices which convert mechanical motion to an AC voltage. Each sensor consists of a wire coil wrapped around a pole piece that is adjacent to a permanent magnet. These elements are contained in a housing which is mounted adjacent to a rotating ferrous member. Two signal wires extend from one end of the housing and an exposed end of the pole piece is located at the opposite end of the housing. The permanent magnet produces lines of flux around the pole piece. As a ferrous object (a rib on the rotating clutch drum) approaches and passes through the gap at the end of the pole piece, an AC voltage pulse is induced in the wire coil. The Transmission Control Module (TCM) calculates the frequency of these AC pulses and converts it to a speed value. The AC voltage generated varies from 150mV at low speed to 15V at high speed. The signal wires from the sensor are formed as twisted pairs to cancel magnetically induced fields. The cable is also shielded to protect from voltage-related fields. Using two-wire differential input at the TCM eliminates noise from other sources.

CONDITIONS FOR RUNNING THE DTC:
1. After TCM initializes normally and output speed is above 200 rpm for at least 0.5 seconds, this DTC test will run at 0.025 second intervals.
2. Shift not in process.
3. Range attained not Neutral (N).
4. For fire truck vocations, pump is not pumping.
5. Turbine speed and output speed DTCs not active.

CONDITIONS FOR SETTING THE DTC:
DTC P0721 sets when one of the following conditions occurs:
1. Output speed change greater than 500 rpm detected within a 0.15 second span.
2. Output speed change greater than 500 rpm detected 5 or more times within a 2 second span.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P0721 is active, the following conditions occur:
1. If the DTC sets while shift not in process, remains in current range.
2. If the DTC sets while shift is in process, complete shift and lock in that range.
3. There is no response to shift selector requests.
4. DTC is stored in TCM history.
5. The CHECK TRANS light illuminates.
6. The TCM inhibits TCC engagement.
7. The TCM freezes shift adapts.

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 the DTC recurring.

DIAGNOSTIC AIDS:
NOTE: When performing any resistance checks for troubleshooting, the current production sensors will have a nominal coil resistance value of 340 Ohms (± 25 Ohms) at an ambient temperature of 20°C (68°F), as compared to the former sensors which had a nominal resistance value of 300 Ohms (± 25 Ohms) at an ambient temperature of 20°C (68°F).

DTC P0721 may be caused by:
1. W140 and/or W160 shorted to another wire in chassis harness or to ground.
2 W140 and/or W160 high resistance or open circuit.
3. Broken or defective connector assemblies allowing pushed back pins to short together.
4. Unlocked connectors, missing seal plugs allowing moisture in connectors.
5. Fatigued wires at speed sensor connectors (broken strands).
6. Incorrect pin crimps or expanded terminals.
7. Defective output speed sensor.
8. Defective TCM.
9. For 3000 Product Family, non-retarder, output speed signal wheel damaged.
10. Wire pair not twisted or not sufficiently twisted.

NOTE: Confirm that the speed sensor wiring consists of twisted pairs at the rate of 12 to 16 twists per 300 mm. These twists must extend the entire length of the wiring harness to within at least 50mm of the speed sensor connector.

NOTE: Drivelines that do not meet ATI specifications (1000 rad/sec² for coast and accel inertials, 500 rad/sec² torsional) can cause this DTC as well as damage internal transmission components, e.g., the output speed signal wheel with spring type roll pin design on 3000 Product Family (non-retarder), rotating drum, clutch plate splines, main case splines, etc. Other speed sensor and range ratio DTCs are usually in history or active when out-of-specification drivelines have caused transmission damage. Always check that vehicle drivelines meet ATI specifications, which include the inter-axle driveline on tandem axle vehicles, the front driveline on 4WD, and any drivelines connected to a PTO or pump, when there is a DTC history for incorrect transmission ratios, turbine, or output speed performance or loss. Refer to Troubleshooting Drivelines for additional information.

NOTE: There is no allowable movement between the output speed signal wheel relative to the P3 carrier (3000 Product Family non-retarder). This is designed to be a press fit between the sides of the wheel groove and the sides of the spring roll pin. Replace both the spring type roll pin and wheel together if there is any radial movement of the wheel relative to the carrier.

Check for wheel movement by using a large screwdriver through the output speed sensor hole in the rear cover and attempt to push the wheel clockwise and counterclockwise. Occasionally a wheel seizes on the spring type roll pin and will still have damage in the slot. By moving the vehicle, selecting a direction change, or operating the transmission to cycle the parts between operating temperature and ambient temperature may help to confirm if wheel damage is present or not. The diagnostic tool 9.0 and later has added a DPID configuration default file to attempt to capture speed signal errors that would be viewable in strip-chart. The default collection file is named SpeedSignalsDatalntegritylist.

NOTE: Select SpeedSignalsDatalntegritylist in DPID configuration prior to connecting with the diagnostic tool in order to strip-chart close to real time speed signal data. Refer to the OEM Technician’s Library for additional information about DPID configuration and data collection.

NOTE: The OEM transmission warranty, or the extended coverage for parts and labor, does not cover transmission or vehicle damage caused by drivelines that do not meet ATI specifications.

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

DIAGNOSTIC RESPONSE:
Default to turbine speed

CIRCUIT DESCRIPTION:
The speed sensors are variable reluctance devices which convert mechanical motion to an AC voltage. Each sensor consists of a wire coil wrapped around a pole piece that is adjacent to a permanent magnet. These elements are contained in a housing which is mounted adjacent to a rotating ferrous member. Two signal wires extend from one end of the housing and an exposed end of the pole piece is at the opposite end of the housing. The permanent magnet produces lines of flux around the pole piece. As a ferrous object (such as a gear tooth) approaches and passes through the gap at the end of the pole piece, an AC voltage pulse is induced in the wire coil. The Transmission Control Module (TCM) calculates the frequency of these AC pulses and converts it to a speed value. The AC voltage generated varies from 150mV at low speed to 15 volts at high speed. The signal wires from the sensor are formed as twisted pairs to cancel magnetically induced fields. The cable is also shielded to protect from voltage-related fields. Noise from other sources is eliminated by using two-wire differential inputs at the TCM.

CONDITIONS FOR RUNNING THE DTC:
1. Engine speed is above 600 rpm for more than 1 second.
2. Shifts complete and range attained not neutral.

CONDITIONS FOR SETTING THE DTC:
DTC P0726 is set when one of the following conditions occur:
1. Engine speed change greater than 600 rpm detected within a 0.15 second span.
2. Engine speed change greater than 650 rpm detected 5 or more times within a 2 second span.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P0726 is active, the following conditions occur:
1. DTC P0726 is stored in the TCM history.
2. The TCM does not illuminate the CHECK TRANS light.
3. If ignition is OFF, then engine speed is set to 0. If turbine speed is greater than the engine speed calibration default value, then substitute turbine speed as engine speed.

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: When performing any resistance checks for troubleshooting, the current production sensors will have a nominal coil resistance value of 340 Ohms (± 25 Ohms) at an ambient temperature of 20°C (68°F), as compared to the former sensors which had a nominal resistance value of 300 Ohms (± 25 Ohms) at an ambient temperature of 20°C (68°F).

DTC P0726 may be caused by:
1. W139 and/or W159 shorted to another wire in chassis harness or to ground.
2. W139 and/or W159 high resistance or open circuit.
3. Broken or defective connector assemblies allowing pushed back pins to short together.
4. Unlocked connectors, missing seal plugs allowing moisture in connectors.
5. Fatigued wires at speed sensor connectors (broken strands).
6. Incorrect pin crimps or expanded terminals.
7. Defective engine speed sensor.
8. Defective TCM.
9. Wire pair not twisted or not sufficiently twisted.

NOTE: Inspect that the speed sensor wiring consists of twisted pairs at the rate of 12 to 16 twists per 300 mm. These twists must extend the entire length of the wiring harness to within at least 50mm of the speed sensor connector.

NOTE: Select SpeedSignalsDatalntegrityList in DPID configuration prior to connecting with the diagnostic tool in order to strip-chart close to real time speed signal data. Refer to the OEM Technician’s Library for additional information about DPID configuration and data collection.

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

DIAGNOSTIC RESPONSE:
Default to turbine speed

CIRCUIT DESCRIPTION:
The speed sensors are variable reluctance devices which convert mechanical motion to an AC voltage. Each sensor consists of a wire coil wrapped around a pole piece that is adjacent to a permanent magnet. These elements are contained in a housing which is mounted adjacent to a rotating ferrous member. Two signal wires extend from one end of the housing and an exposed end of the pole piece is at the opposite end of the housing. The permanent magnet produces lines of flux around the pole piece. As a ferrous object (such as a gear tooth) approaches and passes through the gap at the end of the pole piece, an AC voltage pulse is induced in the wire coil. The Transmission Control Module (TCM) calculates the frequency of these AC pulses and converts it to a speed value. The AC voltage generated varies from 150 mV at low speed to 15 volts at high speed. The signal wires from the sensor are formed as twisted pairs to cancel magnetically induced fields. The cable is also shielded to protect from voltage-related fields. Noise from other sources is eliminated by using two-wire differential inputs at the TCM.

CONDITIONS FOR RUNNING THE DTC:
1. Turbine speed is above 450 rpm.
2. Ignition Key in RUN position and Vehicle is not coasting with engine off.

CONDITIONS FOR SETTING THE DTC:
DTC P0727 is set when one of the following conditions occur:
1. Unrealistic large deceleration in engine speed of 1140 rpm.
2. Engine speed is detected below 61 rpm for 4 seconds.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P0727 is active, the following conditions occur:
1. DTC P0727 is stored in the TCM history.
2. The TCM does not illuminate the CHECK TRANS light.
3. If ignition is OFF, then engine speed is set to 0. If turbine speed is greater than the engine speed calibration default value, then substitute turbine speed as engine speed.

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: When performing any resistance checks for troubleshooting, the current production sensors will have a nominal coil resistance value of 340 Ohms (± 25 Ohms) at an ambient temperature of 20°C (68°F), as compared to the former sensors which had a nominal resistance value of 300 Ohms (± 25 Ohms) at an ambient temperature of 20°C (68°F).

DTC P0727 may be caused by:
1. W139 and/or W159 shorted to another wire in chassis harness or to ground.
2. W139 and/or W159 high resistance or open circuit.
3. Broken or defective connector assemblies allowing pushed back pins to short together.
4. Unlocked connectors, missing seal plugs allowing moisture in connectors.
5. Fatigued wires at speed sensor connectors (broken strands).
6. Incorrect pin crimps or expanded terminals.
7. Defective engine speed sensor.
8. Defective TCM.
9. Wire pair not twisted or not sufficiently twisted.

NOTE: Inspect that the speed sensor wiring consists of twisted pairs at the rate of 12 to 16 twists per 300 mm. These twists must extend the entire length of the wiring harness to within at least 50mm of the speed sensor connector.

NOTE: Select SpeedSignalsDatalntegritylist in DPID configuration prior to connecting with the diagnostic tool in order to strip-chart close to real time speed signal data. Refer to the OEM Technician’s Library for additional information about DPID configuration and data collection.

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

DIAGNOSTIC RESPONSE:
DNS, Attempt 5th, then 3rd

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.

CONDITIONS FOR RUNNING THE DTC:
1. Hydraulic system is pressurized.
2. No shift in progress.
3. Hydraulic default condition not present.
4. Output speed is above 200 rpm.
5. Engine initialization or shutdown is not in process.

CONDITIONS FOR SETTING THE DTC:
DTC P0729 sets during steady-state condition when the calculated sixth gear ratio differs from the known sixth gear ratio for more than 2 seconds.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P0729 is active, the following conditions will occur:
1. The TCM attempts to shift to fifth range. If unsuccessful, the TCM commands third 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 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. 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 action requests for Clutch Test, Full Main Pressure Test, and also the procedure for Stall Testing.

DTC P0729 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. Clutch system issues causing a clutch not to release.
7. Issue with TCM.

DIAGNOSTIC RESPONSE:
DNS, Attempt 2nd, then 5th

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.

CONDITIONS FOR RUNNING THE DTC:
1. Hydraulic system is pressurized.
2. No shift in progress.
3. Hydraulic default condition not present.
4. Output speed is above 200 rpm.
5. Engine initialization or shutdown is not in process.

CONDITIONS FOR SETTING THE DTC:
DTC P0731 sets during steady-state condition when the calculated first gear ratio differs from the known first gear ratio for more than 2 seconds.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P0731 is active, the following conditions will occur:
1. The TCM attempts to shift to second range. If unsuccessful, the TCM commands fifth 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 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. 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 action requests for Clutch Test, Full Main Pressure Test, and also the procedure for Stall Testing.

DTC P0731 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. Clutch system issues causing a clutch not to release.
7. Issue with TCM.

DIAGNOSTIC RESPONSE:
DNS, Attempt 3rd, then 5th

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.

CONDITIONS FOR RUNNING THE DTC:
1. Hydraulic system is pressurized.
2. No shift in progress.
3. Hydraulic default condition not present.
4. Output speed is above 200 rpm.
5. Engine initialization or shutdown is not in process.

CONDITIONS FOR SETTING THE DTC:
DTC P0732 sets during steady-state condition when the calculated second gear ratio differs from the known second gear ratio for more than 2 seconds.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P0732 is active, the following conditions will occur:
1. The TCM attempts to shift to third range. If unsuccessful, the TCM commands fifth 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 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. 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 action requests for Clutch Test, Full Main Pressure Test, and also the procedure for Stall Testing.

DTC P0732 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. Clutch system issues causing a clutch not to release.
7. Issue with TCM.

DIAGNOSTIC RESPONSE:
DNS, Attempt 4th, then 6th

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

CONDITIONS FOR RUNNING THE DTC:
1. Hydraulic system is pressurized.
2. No shift in progress.
3. Hydraulic default condition not present.
4. Output speed is above 200 rpm.
5. Engine initialization or shutdown is not in process.

CONDITIONS FOR SETTING THE DTC:
DTC P0733 sets during steady-state condition when the calculated third gear ratio differs from the known third gear ratio for more than 2 seconds.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P0733 is active, the following conditions will occur:
1. The TCM attempts to shift to fourth. If unsuccessful, the TCM commands sixth 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.

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. 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 action requests for Clutch Test, Full Main Pressure Test, and also the procedure for Stall Testing.

DTC P0733 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. Clutch system issues causing a clutch not to release.
7. Issue with TCM.

DIAGNOSTIC RESPONSE:
DNS, Attempt 5th, then 3rd

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.

CONDITIONS FOR RUNNING THE DTC:
1. Hydraulic system is pressurized.
2. No shift in progress.
3. Hydraulic default condition not present.
4. Output speed is above 200 rpm.
5. Engine initialization or shutdown is not in process.

CONDITIONS FOR SETTING THE DTC:
DTC P0734 sets during steady-state condition when the calculated fourth gear ratio differs from the known fourth gear ratio for more than 2 seconds.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P0734 is active, the following conditions will occur:
1. The ECM attempts to shift to fifth range. If unsuccessful, the TCM commands third 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.

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 action requests for Clutch Test, Full Main Pressure Test, and also the procedure for Stall Testing.

DTC P0734 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. Clutch system issues causing a clutch not to release.
7. Issue with TCM.