Allison

CIRCUIT DESCRIPTION:
HSD2 supplies battery voltage to PCS2, SS1, SS2, SS3 via wire 171. HSD2 is continuously on during normal operation except during brief circuit tests. The TCM regulates control current to the solenoids by switching the appropriate low side driver on and off. DTC P2669 indicates the TCM has detected multiple low side circuits are open while having HSD2 voltage of over a calibrated voltage. DTC P2669 could be caused by open condition in the high side wiring attached to HSD2 (wire 171).

ACTION TAKEN WHEN THE DTC SETS:
When DTC P2669 is active, the following conditions occur:
1. If failure occurs while in a forward range shift to 1st, 3rd, or 5th range is made.
2. While diagnostic response is active, if shift selector is moved to N (Neutral), transmission shifts to neutral; if the shift selector is moved to R (Revere), transmission shifts to reverse. If the shift selector is moved to D (Drive) range or R (Reverse) and transmission is compromised by overspeeding or direction change, transmission shifts to neutral.
3. Torque Converter Clutch (TCC) engagement is inhibited.
4. The DTC is stored in the TCM history.
5. The CHECK TRANS light illuminates.
6. The TCM forces Variable Modulated Main off.
7. 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 the DTC recurring.

DIAGNOSTIC AIDS:
The following procedures are not documented in any OEM procedures or in any OEM Troubleshooting or Service information and should not be used as a method to diagnose any transmission DTCs, function, or shift quality concern:

1. Back-probing any connections used for transmission features or functions may damage and/or unlock terminals from the back-probed connector creating permanent or intermittent shorts and/or open circuits. If possible, use the J-39700 Breakout Box, the appropriate harness adapters, and appropriate magnetic overlays to troubleshoot the vehicle.

2. Load-testing any transmission-related circuits with any other electrical devices such as vehicle lamps or relays, especially with the TCM connected to the harness. Use J-39700 Breakout Box and appropriate harnesses with the diagnostic tool to monitor the circuit performance in question unless otherwise specified in the various Troubleshooting information.

3. Piercing a wire to check for voltages, shorts-to-grounds or other wires anywhere in the circuit but especially at the TCM. This creates a leak path for moisture and damages the wire and insulation.

An intermittent circuit condition can allow this DTC to set. Make sure you check for the following conditions at the OEM harness first, then at the transmission internal harness:

Inspect the wiring for poor electrical connections at the TCM and the transmission main connector. Look for the following conditions:
1. A bent terminal.
2. A backed-out terminal.
3. A damaged terminal.
4. Poor terminal tension.
5. A chafed wire.
6. A broken wire inside the insulation.

Inspect OEM wiring harness routing. Look for possible contact points where chafing could occur leading to an open circuit condition. Moving parts on the vehicle could be contacting the harness; this includes parking brake drum, suspension components, transmission shift linkage, etc.

When diagnosing for an intermittent open condition, massage the wiring harness while watching the test equipment for a change.

You may have to drive the vehicle in order to experience a fault. Use the data obtained from failure records to determine transmission range and/or certain vehicle operating variables such as temperature, run time, etc. This data can be useful in reproducing the failure mode when the DTC was set.

CIRCUIT DESCRIPTION:
HSD2 supplies battery voltage to PCS2, SS1, SS2, SS3 via wire 171. HSD2 is continuously on during normal operation except during brief circuit tests. The TCM regulates control current to the solenoids by switching the appropriate low side driver on and off. DTC P2670 indicates the TCM has detected that all solenoids connected to the HSD2 are inactive with a supply voltage in the HSD2 circuit lower than a calibrated voltage. DTC 2670 indicates a short-to-ground has occurred in the high side wiring attached to HSD2 (wire 171).

ACTION TAKEN WHEN THE DTC SETS:
When DTC P2670 is active, the following conditions occur:
1. If failure occurs while in a forward range shift to 1st, 3rd, or 5th range is made.
2. While diagnostic response is active, if shift selector is moved to N (Neutral), transmission shifts to neutral; if the shift selector is moved to R (Revere), transmission shifts to reverse. If the shift selector is moved to D (Drive) range or R (Reverse) and transmission is compromised by overspeeding or direction change, transmission shifts to neutral.
3. Torque Converter Clutch (TCC) engagement is inhibited.
4. The DTC is stored in the TCM history.
5. The CHECK TRANS light illuminates.
6. The TCM forces Variable Modulated Main off.
7. 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 the DTC recurring.

DIAGNOSTIC AIDS:
The following procedures are not documented in any OEM procedures or in any OEM Troubleshooting or Service information and should not be used as a method to diagnose any transmission DTCs, function, or shift quality concern:

1. Back-probing any connections used for transmission features or functions may damage and/or unlock terminals from the back-probed connector creating permanent or intermittent shorts and/or open circuits. If possible, use the J-39700 Breakout Box, the appropriate harness adapters, and appropriate magnetic overlays to troubleshoot the vehicle.

2. Load-testing any transmission-related circuits with any other electrical devices such as vehicle lamps or relays, especially with the TCM connected to the harness. Use J-39700 Breakout Box and appropriate harnesses with the diagnostic tool to monitor the circuit performance in question unless otherwise specified in the various Troubleshooting information.

3. Piercing a wire to check for voltages, shorts-to-grounds or other wires anywhere in the circuit but especially at the TCM. This creates a leak path for moisture and damages the wire and insulation.

4. The high side drivers (HSD1 and HSD2) reset opening the high side circuit whenever a short-to-ground is detected.

Inspect the wiring for poor electrical connections at the TCM and the transmission main connector. Look for the following conditions:
1. A bent terminal.
2. A backed-out terminal.
3. A damaged terminal.
4. Poor terminal tension.
5. A chafed wire.
6. A broken wire inside the insulation.

Inspect OEM wiring harness routing. Look for possible contact points where chafing could occur leading to an open circuit condition. Moving parts on the vehicle could be contacting the harness; this includes parking brake drum, suspension components, transmission shift linkage, etc.

When diagnosing for an intermittent open condition, massage the wiring harness while watching the test equipment for a change.

You may have to drive the vehicle in order to experience a fault. Use the data obtained from failure records to determine transmission range and/or certain vehicle operating variables such as temperature, run time, etc. This data can be useful in reproducing the failure mode when the DTC was set.

CIRCUIT DESCRIPTION:
HSD2 supplies battery voltage to PCS2, SS1, SS2, SS3 via wire 171. HSD2 is continuously on during normal operation except during brief circuit tests. The TCM regulates control current to the solenoids by switching the appropriate low side driver on and off. DTC P2671 indicates the TCM has detected greater than or equal to calibrated voltage in the HSD2 circuit when HSD2 is off during TCM initialization. This indicates a short to battery exists on the high side circuit 171.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P2671 is active, the following conditions occur:
1. If failure occurs while in a forward range shift to 1st, 3rd, or 5th range is made.
2. While diagnostic response is active, if shift selector is moved to N (Neutral), transmission shifts to neutral; if the shift selector is moved to R (Revere), transmission shifts to reverse. If the shift selector is moved to D (Drive) range or R (Reverse) and transmission is compromised by overspeeding or direction change, transmission shifts to neutral.
3. Torque Converter Clutch (TCC) engagement is inhibited.
4. The DTC is stored in the TCM history.
5. The CHECK TRANS light illuminates.
6. The TCM forces Variable Modulated Main off.
7. 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 the DTC recurring.

DIAGNOSTIC AIDS:
The following procedures are not documented in any OEM procedures or in any OEM Troubleshooting or Service information and should not be used as a method to diagnose any transmission DTCs, function, or shift quality concern:

1. Back-probing any connections used for transmission features or functions may damage and/or unlock terminals from the back-probed connector creating permanent or intermittent shorts and/or open circuits. If possible, use the J-39700 Breakout Box, the appropriate harness adapters, and appropriate magnetic overlays to troubleshoot the vehicle.

2. Load-testing any transmission-related circuits with any other electrical devices such as vehicle lamps or relays, especially with the TCM connected to the harness. Use J-39700 Breakout Box and appropriate harnesses with the diagnostic tool to monitor the circuit performance in question unless otherwise specified in the various Troubleshooting information.

3. Piercing a wire to check for voltages, shorts-to-grounds or other wires anywhere in the circuit but especially at the TCM. This creates a leak path for moisture and damages the wire and insulation.

Inspect the wiring for poor electrical connections at the TCM and the transmission main connector. Look for the following conditions:
1. A bent terminal.
2. A backed-out terminal.
3. A damaged terminal.
4. Poor terminal tension.
5. A chafed wire.
6. A broken wire inside the insulation.

Inspect OEM wiring harness routing. Look for possible contact points where chafing could occur leading to an open circuit condition. Moving parts on the vehicle could be contacting the harness; this includes parking brake drum, suspension components, transmission shift linkage, etc.

When diagnosing for an intermittent open condition, massage the wiring harness while watching the test equipment for a change.

You may have to drive the vehicle in order to experience a fault. Use the data obtained from failure records to determine transmission range and/or certain vehicle operating variables such as temperature, run time, etc. This data can be useful in reproducing the failure mode when the DTC was set.

CIRCUIT DESCRIPTION:
HSD3 supplies battery voltage to PCS3 via wire 131. HSD3 is continuously on during normal operation except during brief circuit tests. The TCM regulates control current to the solenoids by switching the appropriate low side driver on and off. DTC P2684 indicates the TCM has detected multiple low side circuits are open while having HSD3 voltage of over a calibrated voltage. DTC P2684 could be caused by an open condition in the high side wiring attached to HSD3 (wire 131).

ACTION TAKEN WHEN THE DTC SETS:
When the DTC P2684 is active, the following conditions occur:
1. All ranges will be available, but RELS will not function.
2. The DTC is stored in the TCM history.
3. The CHECK TRANS light illuminates.

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:
The following procedures are not documented in any OEM procedures or in any OEM Troubleshooting or Service information and should not be used as a method to diagnose any transmission DTCs, function, or shift quality concern:

1. Back-probing any connections used for transmission features or functions may damage and/or unlock terminals from the back-probed connector creating permanent or intermittent shorts and/or open circuits. If possible, use the J-39700 Breakout Box, the appropriate harness adapters, and appropriate magnetic overlays to troubleshoot the vehicle.

2. Load-testing any transmission-related circuits with any other electrical devices such as vehicle lamps or relays, especially with the TCM connected to the harness. Use J-39700 Breakout Box and appropriate harnesses with the diagnostic tool to monitor the circuit performance in question unless otherwise specified in the various Troubleshooting information.

3. Piercing a wire to check for voltages, shorts-to-grounds or other wires anywhere in the circuit but especially at the TCM. This creates a leak path for moisture and damages the wire and insulation.

An intermittent circuit condition can allow this DTC to set. Make sure you check for the following conditions at the OEM harness first, then at the transmission internal harness:

Inspect the wiring for poor electrical connections at the TCM and the transmission main connector. Look for the following conditions:
1. A bent terminal.
2. A backed-out terminal.
3. A damaged terminal.
4. Poor terminal tension.
5. A chafed wire.
6. A broken wire inside the insulation.

Inspect OEM wiring harness routing. Look for possible contact points where chafing could occur leading to an open circuit condition. Moving parts on the vehicle could be contacting the harness; this includes parking brake drum, suspension components, transmission shift linkage, etc.

When diagnosing for an intermittent short, massage the wiring harness while watching the test equipment for a change.

You may have to drive the vehicle in order to experience a fault. Use the data obtained from failure records to determine transmission range and/or certain vehicle operating variables such as temperature, run time, etc. This data can be useful in reproducing the failure mode when the DTC was set.

CIRCUIT DESCRIPTION:
HSD3 supplies battery voltage to PCS3 via wire 131. HSD3 is continuously on during normal operation except during brief circuit tests. The TCM regulates control current to the solenoids by switching the appropriate low side driver on and off. DTC P2685 indicates the TCM has detected that all solenoids connected to the HSD3 are inactive with a supply voltage in the HSD3 circuit lower than a calibrated voltage. DTC P2685 indicates a short-to-ground has occurred in the high side wiring attached to HSD3 (wire 131).

ACTION TAKEN WHEN THE DTC SETS:
When the DTC P2685 is active, the following conditions occur:
1. All ranges will be available, but Neutral at Stop will not function.
2. The DTC is stored in the TCM history.
3. The CHECK TRANS light illuminates.

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:
The following procedures are not documented in any OEM procedures or in any OEM Troubleshooting or Service information and should not be used as a method to diagnose any transmission DTCs, function, or shift quality concern:

1. Back-probing any connections used for transmission features or functions may damage and/or unlock terminals from the back-probed connector creating permanent or intermittent shorts and/or open circuits. If possible, use the J-39700 Breakout Box, the appropriate harness adapters, and appropriate magnetic overlays to troubleshoot the vehicle.

2. Load-testing any transmission-related circuits with any other electrical devices such as vehicle lamps or relays, especially with the TCM connected to the harness. Use J-39700 Breakout Box and appropriate harnesses with the diagnostic tool to monitor the circuit performance in question unless otherwise specified in the various Troubleshooting information.

3. Piercing a wire to check for voltages, shorts-to-grounds or other wires anywhere in the circuit but especially at the TCM. This creates a leak path for moisture and damages the wire and insulation.

Inspect the wiring for poor electrical connections at the TCM and the transmission main connector. Look for the following conditions:
1. A bent terminal.
2. A backed-out terminal.
3. A damaged terminal.
4. Poor terminal tension.
5. A chafed wire.
6. A broken wire inside the insulation.

Inspect OEM wiring harness routing. Look for possible contact points where chafing could occur leading to an open circuit condition. Moving parts on the vehicle could be contacting the harness; this includes parking brake drum, suspension components, transmission shift linkage, etc.

When diagnosing for an intermittent short, massage the wiring harness while watching the test equipment for a change.

You may have to drive the vehicle in order to experience a fault. Use the data obtained from failure records to determine transmission range and/or certain vehicle operating variables such as temperature, run time, etc. This data can be useful in reproducing the failure mode when the DTC was set.

CIRCUIT DESCRIPTION:
HSD3 supplies battery voltage to PCS3 via wire 131. HSD3 is continuously on during normal operation except during brief circuit tests. The TCM regulates control current to the solenoids by switching the appropriate low side driver on and off. DTC P2686 indicates the TCM has detected greater than or equal to a calibrated voltage in the HSD3 circuit when HSD3 is off during TCM initialization. This indicates a short to battery exists on the high side circuit 131.

ACTION TAKEN WHEN THE DTC SETS:
When the DTC P2686 is active, the following conditions occur:
1. All ranges will be available, but Neutral at Stop will not function.
2. The DTC is stored in the TCM history.
3. The CHECK TRANS light illuminates.

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:
The following procedures are not documented in any OEM procedures or in any OEM Troubleshooting or Service information and should not be used as a method to diagnose any transmission DTCs, function, or shift quality concern:

1. Back-probing any connections used for transmission features or functions may damage and/or unlock terminals from the back-probed connector creating permanent or intermittent shorts and/or open circuits. If possible, use the J-39700 Breakout Box, the appropriate harness adapters, and appropriate magnetic overlays to troubleshoot the vehicle.

2. Load-testing any transmission-related circuits with any other electrical devices such as vehicle lamps or relays, especially with the TCM connected to the harness. Use J-39700 Breakout Box and appropriate harnesses with the diagnostic tool to monitor the circuit performance in question unless otherwise specified in the various Troubleshooting information.

3. Piercing a wire to check for voltages, shorts-to-grounds or other wires anywhere in the circuit but especially at the TCM. This creates a leak path for moisture and damages the wire and insulation.

Inspect the wiring for poor electrical connections at the TCM and the transmission main connector. Look for the following conditions:
1. A bent terminal.
2. A backed-out terminal.
3. A damaged terminal.
4. Poor terminal tension.
5. A chafed wire.
6. A broken wire inside the insulation.

Inspect OEM wiring harness routing. Look for possible contact points where chafing could occur leading to an open circuit condition. Moving parts on the vehicle could be contacting the harness; this includes parking brake drum, suspension components, transmission shift linkage, etc.

When diagnosing for an intermittent short, massage the wiring harness while watching the test equipment for a change.

You may have to drive the vehicle in order to experience a fault. Use the data obtained from failure records to determine transmission range and/or certain vehicle operating variables such as temperature, run time, etc. This data can be useful in reproducing the failure mode when the DTC was set.

CIRCUIT DESCRIPTION:
PCS1 is used to control oncoming, off-going, and holding pressure in any one of five clutches. This solenoid is referred to as Pressure Proportional to Current (PPC) since the output hydraulic pressure supplied by this solenoid is proportional to the controlled current command.

The TCM uses information from the turbine and output speed sensors to detect if a clutch is slipping. The clutch being controlled by PCS1 varies depending on the shift that is being completed. DTC P2723 sets when the TCM detects an incorrect oncoming ratio (range to range) for an accumulated number of occurrences.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P2723 is active, the following conditions occur:
1. If failure occurs while in a forward range, the transmission shifts to the previous range.
2. If failure occurs while in N (Neutral) or R (Reverse), the transmission locks in N (Neutral).
3. If the shift selector is moved to N (Neutral), the transmission shifts to N (Neutral) (some cases may lock in N (Neutral)).
4. If the shift selector is moved to R (Reverse), the transmission shifts to R (Reverse) or N (Neutral)
5. If the shift selector is returned to a forward range and the transmission is compromised by overspeeding or a direction change, the transmission shifts to N (Neutral).
6. The CHECK TRANS light illuminates (non-OBD II strategy).
7. TCM inhibits Torque Converter Clutch (TCC) engagement.
8. The DTC is stored in the TCM history.
9. The TCM forces Variable Modulated Main off.
10. 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 the DTC recurring.

DIAGNOSTIC AIDS:
The following procedures are not documented in any OEM procedures or in any OEM Troubleshooting or Service information and should not be used as a method to diagnose any transmission DTCs, function, or shift quality concern:

1. Back-probing any connections used for transmission features or functions may damage and/or unlock terminals from the back-probed connector creating permanent or intermittent shorts and/or open circuits. If possible, use the J-39700 Breakout Box, the appropriate harness adapters, and appropriate magnetic overlays to troubleshoot the vehicle.

2. Load-testing any transmission-related circuits with any other electrical devices such as vehicle lamps or relays, especially with the TCM connected to the harness. Use J-39700 Breakout Box and appropriate harnesses with the diagnostic tool to monitor the circuit performance in question unless otherwise specified in the various Troubleshooting information.

3. Piercing a wire to check for voltages, shorts-to-grounds or other wires anywhere in the circuit but especially at the TCM. This creates a leak path for moisture and damages the wire and insulation.

4. This DTC indicates the oncoming clutch being controlled by PCS1 is not applied or applied too slowly. This could indicate a leak or obstruction in a specific clutch apply circuit. Check the diagnostic tool failure record data for previous or current range information to determine the specific shift when the DTC was set. Refer to SOLENOID AND CLUTCH information to determine which clutch circuit is suspect.

If the condition is intermittent, connect the diagnostic tool and select the speed sensor indicated by the DTC. If the signal is erratic, investigate and eliminate the following:
1. Intermittent wiring connection
2. Excessive vibration (driveline or engine torsionals)
3. Irregular sensor gap (loose sensor, loose or damaged tone wheel)

Inspect and confirm that the OEM engine rating does not exceed the transmission model rating. Also inspect for the presence of an add-on engine power package or module. Whenever the engine horsepower or torque is increased over the transmission factory rating, a shift flare condition may occur leading to the DTC indicated.

NOTE: Clutch failure due to an OEM engine rating exceeding the OEM transmission rating, or the installation of an engine power package or module will not be covered under the OEM transmission warranty.

CIRCUIT DESCRIPTION:
PCS1 is used to control oncoming, off-going, and holding pressure in any one of five clutches. This solenoid is referred to as Pressure Proportional to Current (PPC) since the output hydraulic pressure supplied by this solenoid is proportional to the controlled current command.

The TCM uses information from the turbine and output speed sensors to detect if a clutch is in a tie-up condition or 3 clutches are applied. The clutch being controlled by PCS1 varies depending on the shift. DTC P2724 sets when the TCM detects an incorrect range to range ratio for an accumulated number of occurrences.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P2724 is active, the following conditions occur:
1. If failure occurs while in a forward range, the transmission shifts to the previous range.
2. If failure occurs while in N (Neutral) or R (Reverse), the transmission locks in N (Neutral).
3. If the shift selector is moved to N (Neutral), the transmission shifts to R (Reverse) or N (Neutral) (some cases may lock in N (Neutral)).
4. If the shift selector is moved to R (Reverse), the transmission shifts to R (Reverse) or N (Neutral)
5. If the shift selector is returned to a forward range and the transmission is compromised by overspeeding or a direction change, the transmission shifts to N (Neutral).
6. The CHECK TRANS light illuminates (non-OBD II strategy).
7. The DTC is stored in the TCM history.
8. The TCM forces Variable Modulated Main off.
9. The TCM freezes shift adapts (DNA).
10. The TCM inhibits Torque Converter Clutch (TCC) engagement.

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:
The following procedures are not documented in any OEM procedures or in any OEM Troubleshooting or Service information and should not be used as a method to diagnose any transmission DTCs, function, or shift quality concern:

1. Back-probing any connections used for transmission features or functions may damage and/or unlock terminals from the back-probed connector creating permanent or intermittent shorts and/or open circuits. If possible, use the J-39700 Breakout Box, the appropriate harness adapters, and appropriate magnetic overlays to troubleshoot the vehicle.

2. Load-testing any transmission-related circuits with any other electrical devices such as vehicle lamps or relays, especially with the TCM connected to the harness. Use J-39700 Breakout Box and appropriate harnesses with the diagnostic tool to monitor the circuit performance in question unless otherwise specified in the various Troubleshooting information.

3. Piercing a wire to check for voltages, shorts-to-grounds or other wires anywhere in the circuit but especially at the TCM. This creates a leak path for moisture and damages the wire and insulation.

4. This DTC indicates the oncoming clutch being controlled by PCS1 is not applied or applied too slowly. This could indicate a leak or obstruction in a specific clutch apply circuit. Check the diagnostic tool failure record data for previous or current range information to determine the specific shift when the DTC was set. Refer to SOLENOID AND CLUTCH information to determine which clutch circuit is suspect.

If the condition is intermittent, connect the diagnostic tool and select the speed sensor indicated by the DTC. If the signal is erratic, investigate and eliminate the following:
1. Intermittent wiring connection
2. Excessive vibration (driveline or engine torsionals)
3. Irregular sensor gap (loose sensor, loose or damaged tone wheel)

Inspect and confirm that the OEM engine rating does not exceed the transmission model rating. Also inspect for the presence of an add-on engine power package or module. Whenever the engine horsepower or torque is increased over the transmission factory rating, a shift flare condition may occur leading to the DTC indicated.

NOTE: Clutch failure due to an OEM engine rating exceeding the OEM Transmission rating, or the installation of an engine power package or module will not be covered under the OEM Transmission warranty.

CIRCUIT DESCRIPTION:
PCPS1 is a Pressure Proportional to Current (PPC) solenoid used to control oncoming and off-going and holding pressure to any one of five clutches.

The TCM sends control current to PCS1 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 PCS1 by switching the low side driver on and off. Wire 155 completes the circuit between PCS1 and its low side driver. DTC P2727 indicates that the TCM processor has detected an open condition in the electrical circuit. The open condition may exist in the high side (wire 111) or low side (wire 155).

ACTION TAKEN WHEN THE DTC SETS:
When DTC P2727 is active, the following conditions occur:
1. If the failure occurs while in a forward range a shift to 1st, 3rd, or 5th range is made.
2. While diagnostic response is active, if shift selector is moved to N (Neutral), transmission shifts to neutral; if the shift selector is moved to R (Revere), transmission shifts to reverse. If the shift selector is moved to D (Drive) range or R (Reverse) and transmission is compromised by overspeeding or direction change, transmission shifts to N (Neutral).
3. The CHECK TRANS light illuminates (non-OBD II strategy).
4. The TCM forces Variable Modulated Main off.
5. The DTC is stored in the TCM history.

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:
The following procedures are not documented in any OEM procedures or in any OEM Troubleshooting or Service information and should not be used as a method to diagnose any transmission DTCs, function, or shift quality concern:

1. Back-probing any connections used for transmission features or functions may damage and/or unlock terminals from the back-probed connector creating permanent or intermittent shorts and/or open circuits. If possible, use the J-39700 Breakout Box, the appropriate harness adapters, and appropriate magnetic overlays to troubleshoot the vehicle.

2. Load-testing any transmission-related circuits with any other electrical devices such as vehicle lamps or relays, especially with the TCM connected to the harness. Use J-39700 Breakout Box and appropriate harnesses with the diagnostic tool to monitor the circuit performance in question unless otherwise specified in the various Troubleshooting information.

3. Piercing a wire to check for voltages, shorts-to-grounds or other wires anywhere in the circuit but especially at the TCM. This creates a leak path for moisture and damages the wire and insulation.

An intermittent circuit condition can allow this DTC to set. Make sure you check for the following conditions at the OEM harness first, then at the transmission internal harness:

DTC P2727 indicates an open in the electrical circuit for the PCS1. In addition to PCS1, HSD1 also supplies power to the Main Mod and TCC solenoids. If DTC P2727 is accompanied by DTC P0960 and/or DTC P2761, the open is most likely in the high side of the circuit.

Inspect the wiring for poor electrical connections at the TCM and the transmission main connector. Look for the following conditions:
1. A bent terminal.
2. A backed-out terminal.
3. A damaged terminal.
4. Poor terminal tension.
5. A chafed wire.
6. A broken wire inside the insulation.

Inspect OEM wiring harness routing. Look for possible contact points where chafing could occur leading to an open circuit condition. Moving parts on the vehicle could be contacting the harness; this includes parking brake drum, suspension components, transmission shift linkage, etc.

When diagnosing for an intermittent open condition, massage the wiring harness while watching the test equipment for a change. It may be necessary to check continuity at individual wires within a harness to isolate an intermittent circuit ground condition.

You may have to drive the vehicle in order to experience a fault. Use the data obtained from failure records to determine transmission range and/or certain vehicle operating variables such as temperature, run time, etc. This data can be useful in reproducing the failure mode when the DTC was set.