Automatic Transaxle Diagnostics (DTC p1820, 3.4l to DTC u2105, 3.6l) (4T65-e) Buick Rendezvous I

Scheme 117

Circuit Description

The transmission internal mode switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The four inputs to the PCM indicate the position of the transmission range selector. The input voltage level at the PCM is high, B+, when the IMS is open and low when the switch is closed to ground. The four input parameters represented are Signals A, B, C and P - Parity. Refer to Transmission Internal Mode Switch Logic .

If the PCM detects that IMS Signal A is always low, then DTC P1820 sets. DTC P1820 is a type C DTC.

Conditions for Running the DTC

1. No MAP DTC P0107 or P0108.
2. The engine speed is greater than 500 RPM for 5 seconds and not in fuel cut off.
3. Engine torque is 55-407 N.m (40-300 lb ft).

Conditions for Setting the DTC

The IMS Signal A is continuously low this ignition cycle, and the following conditions occur

1. The IMS indicates PARK for 2 seconds, then
2. The IMS indicates transitional position D4-D3 for 60 seconds.

Action Taken When the DTC Sets

1. The PCM does not illuminate the malfunction indicator lamp (MIL).
2. The PCM commands maximum line pressure.
3. The PCM freezes transmission adaptive functions.
4. The PCM assumes D4 for shifting.
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
6. The PCM stores DTC P1820 in PCM history.

Conditions for Clearing the DTC

1. A scan tool can clear the DTC.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 3: A low value for Signal A indicates a short to ground in the engine harness or the PCM.
2. 5: This step tests the internal transmission harness. A value of LOW for Signal A indicates the fault is in the harness. Otherwise the fault will be in the switch.

DTC P1820 (3.4L)

Scheme 118

The transmission internal mode switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The four inputs to the TCM indicate the position of the transmission range selector. The input voltage level at the TCM is high, B+, when the IMS is open and low when the switch is closed to ground. The four input parameters represented are Signals A, B, C and P - Parity. Refer to Transmission Internal Mode Switch Logic .

If the TCM detects that IMS Signal A is always low, then DTC P1820 sets. DTC P1820 is a type B DTC.

1. No MAP DTC P0107 or P0108.
2. Engine torque is greater than 50 N.m (37 lb ft).

The IMS Signal A is continuously low this ignition cycle, and the following conditions occur

1. The IMS indicates PARK for 0.25 seconds, then
2. The IMS indicates transitional position D4-D3 for 60 seconds.

1. The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
2. The TCM commands maximum line pressure.
3. The TCM freezes transmission adaptive functions.
4. The TCM assumes D4 for shifting.
5. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
6. The TCM stores DTC P1820 in TCM history during the second consecutive trip in which the Conditions for Setting the DTC are met..

1. The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send an MIL illumination request.
2. A scan tool can clear the DTC.
3. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: A low value for Signal A indicates a short to ground in the engine harness or the TCM.
2. 5: This step tests the internal transmission harness. A value of LOW for Signal A indicates the fault is in the harness. Otherwise the fault will be in the switch.

DTC P1820 (3.6L)

The transmission internal mode switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The four inputs to the PCM indicate the position of the transmission range selector. The input voltage level at the PCM is high, B+, when the IMS is open and low when the switch is closed to ground. The four input parameters represented are Signals A, B, C and P - Parity. Refer to Transmission Internal Mode Switch Logic .

If the PCM detects that IMS Signal B is always high, then DTC P1822 sets. DTC P1822 is a type C DTC.

1. No MAP DTC P0107 or P0108.
2. Engine torque is 55-407 N.m (40-300 lb ft).
3. The engine speed is greater than 500 RPM for 5 seconds and not in fuel cut off.

The IMS Signal B is continuously high this ignition cycle, and the following conditions occur

1. The IMS indicates PARK for 2 seconds, then
2. The IMS indicates transitional position D2-D1 for 60 seconds.

1. The PCM does not illuminate the malfunction indicator lamp (MIL).
2. The PCM commands maximum line pressure.
3. The PCM freezes transmission adaptive functions.
4. The PCM assumes D4 for shifting.
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
6. The PCM stores DTC P1822 in PCM history.

1. A scan tool can clear the DTC.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

The number below refers to the step number on the diagnostic table.

1. 3: This step tests the integrity of the engine harness and PCM by checking for the Signal B state change from HI to LOW. A LOW signal indicates the fault is either in the internal transmission harness or the switch. A HI signal indicates the fault is either in the engine harness or the PCM.

DTC P1822 (3.4L)

The transmission internal mode switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The four inputs to the TCM indicate the position of the transmission range selector. The input voltage level at the TCM is high, B+, when the IMS is open and low when the switch is closed to ground. The four input parameters represented are Signals A, B, C and P - Parity. Refer to Transmission Internal Mode Switch Logic .

If the TCM detects that IMS Signal B is always high, then DTC P1822 sets. DTC P1822 is a type B DTC.

1. No MAP DTC P0107 or P0108.
2. Engine torque is greater than 50 N.m (37 lb ft).

The IMS Signal B is continuously high this ignition cycle, and the following conditions occur

1. The IMS indicates PARK for 0.25 seconds, then
2. The IMS indicates transitional position D2-D1 for 60 seconds.

1. The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the consecutive trip in which the Conditions for Setting the DTC are met.
2. The TCM commands maximum line pressure.
3. The TCM freezes transmission adaptive functions.
4. The TCM assumes D4 for shifting.
5. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
6. The TCM stores DTC P1822 in TCM history during the consecutive trip in which the Conditions for Setting the DTC are met.

1. A scan tool can clear the DTC.
2. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
3. The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

The number below refers to the step number on the diagnostic table.

1. 3: This step tests the integrity of the engine harness and TCM by checking for the Signal B state change from HI to LOW. A LOW signal indicates the fault is either in the internal transmission harness or the switch. A HI signal indicates the fault is either in the engine harness or the TCM.

DTC P1822 (3.6L)

The transmission internal mode switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The four inputs to the PCM indicate the position of the transmission range selector. The input voltage level at the PCM is high, B+, when the IMS is open and low when the switch is closed to ground. The four input parameters represented are Signals A, B, C and P - Parity. Refer to Transmission Internal Mode Switch Logic .

If the PCM detects that IMS Signal P is always low, then DTC P1823 sets. DTC P1823 is a type C DTC.

1. No MAP DTC P0107 or P0108.
2. The engine speed is greater than 500 RPM for 5 seconds and not in fuel cut off.
3. Engine torque is 55-407 N.m (40-300 lb ft).

The IMS Signal P is continuously low this ignition cycle, and the following conditions occur

1. The IMS indicates PARK for 2 seconds, then
2. The IMS indicates transitional position N-D4 for 60 seconds.

1. The PCM does not illuminate the malfunction indicator lamp (MIL).
2. The PCM commands maximum line pressure.
3. The PCM freezes transmission adaptive functions.
4. The PCM assumes D4 for shifting.
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
6. The PCM stores DTC P1823 in PCM history.

1. A scan tool can clear the DTC.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: A LOW signal indicates a short to ground in the vehicle harness or the PCM.
2. 5: This step tests the internal transmission harness without the IMS connected.

DTC P1823 (3.4L)

The transmission internal mode switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The four inputs to the TCM indicate the position of the transmission range selector. The input voltage level at the TCM is high, B+, when the IMS is open and low when the switch is closed to ground. The four input parameters represented are Signals A, B, C and P - Parity. Refer to Transmission Internal Mode Switch Logic .

If the TCM detects that IMS Signal P is always low, then DTC P1823 sets. DTC P1823 is a type C DTC.

1. No MAP DTC P0107 or P0108.
2. Engine torque is greater than 50 N.m (37 lb ft).

The IMS Signal P is continuously low this ignition cycle, and the following conditions occur

1. The IMS indicates PARK for 0.25 seconds, then
2. The IMS indicates transitional position N-D4 for 60 seconds.

1. The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the consecutive trip in which the Conditions for Setting the DTC are met.
2. The TCM commands maximum line pressure.
3. The TCM freezes transmission adaptive functions.
4. The TCM assumes D4 for shifting.
5. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
6. The TCM stores DTC P1823 in TCM history during the consecutive trip in which the Conditions for Setting the DTC are met.

1. A scan tool can clear the DTC.
2. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
3. The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: A LOW signal indicates a short to ground in the vehicle harness or the TCM.
2. 5: This step tests the internal transmission harness without the IMS connected.

DTC P1823 (3.6L)

The transmission internal mode switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The four inputs to the PCM indicate the position of the transmission range selector. The input voltage level at the PCM is high, B+, when the IMS is open and low when the switch is closed to ground. The four input parameters represented are Signals A, B, C and P - Parity. Refer to Transmission Internal Mode Switch Logic .

If the PCM detects an invalid transmission range with the engine running, then DTC P1825 sets. DTC P1825 is a type C DTC.

The engine speed is at least 500 RPM for 5 seconds and not in fuel cut off.

The PCM detects an invalid combination of IMS signals for 60 seconds.

1. The PCM does not illuminate the malfunction indicator lamp (MIL).
2. The PCM commands maximum line pressure.
3. The PCM freezes transmission adaptive functions.
4. The PCM assumes D4 for shifting.
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
6. The PCM stores DTC P1825 in PCM history.

1. A scan tool can clear the DTC.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: HI values for all signals in all ranges indicates the ground circuit is OPEN.
2. 4: With the 20-way connector disconnected, all signals should indicate HI.
3. 6: If one circuit affects the other, this indicates a short between the two circuits.
4. 13: This step tests the internal transmission harness. If no fault is found in the harness, the fault will be in the switch.

DTC P1825 (3.4L)

The transmission internal mode switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The four inputs to the TCM indicate the position of the transmission range selector. The input voltage level at the TCM is high, B+, when the IMS is open and low when the switch is closed to ground. The four input parameters represented are Signals A, B, C and P - Parity. Refer to Transmission Internal Mode Switch Logic .

If the TCM detects an invalid transmission range with the engine running, then DTC P1825 sets. DTC P1825 is a type B DTC.

The system voltage is 8-18 volts.

The TCM detects an invalid combination of IMS signals for 60 seconds.

1. The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the consecutive trip in which the Conditions for Setting the DTC are met.
2. The TCM commands maximum line pressure.
3. The TCM freezes transmission adaptive functions.
4. The TCM assumes D4 for shifting.
5. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
6. The TCM stores DTC P1825 in TCM history during the consecutive trip in which the Conditions for Setting the DTC are met.

1. A scan tool can clear the DTC.
2. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
3. The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: HI values for all signals in all ranges indicates the ground circuit is OPEN.
2. 4: With the 20-way connector disconnected, all signals should indicate HI.
3. 6: If one circuit affects the other, this indicates a short between the two circuits.
4. 13: This step tests the internal transmission harness. If no fault is found in the harness, the fault will be in the switch.

DTC P1825 (3.6L)

The transmission internal mode switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The four inputs to the PCM indicate the position of the transmission range selector. The input voltage level at the PCM is high, B+, when the IMS is open and low when the switch is closed to ground. The four input parameters represented are Signals A, B, C and P - Parity. Refer to Transmission Internal Mode Switch Logic .

If the PCM detects that IMS Signal C is high while the vehicle is being driven in a forward gear, then DTC P1826 sets. DTC P1826 is a type C DTC.

1. No VSS DTCs P0502 or P0503.
2. Vehicle speed is 16 km/h (10 mph) or greater.
3. Engine torque is 27 N.m (20 lb ft) or greater.
4. DTC P1826 has not passed this key cycle.

The PCM detects IMS Signal C is high, while the gear ratio indicates first, second, third or fourth gear for 60 seconds.

1. The PCM does not illuminate the malfunction indicator lamp (MIL).
2. The PCM commands maximum line pressure.
3. The PCM freezes transmission adaptive functions.
4. The PCM assumes D4 for shifting.
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
6. The PCM stores DTC P1826 in PCM history.

1. A scan tool can clear the DTC.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

The number below refers to the step number on the diagnostic table.

1. 3: This step tests the integrity of the engine harness and PCM by checking for the Signal C state change from HI to LOW. A LOW signal indicates the fault is either in the internal transmission harness or the switch. A HI signal indicates the fault is either in the engine harness or the PCM.

DTC P1826 (3.4L)

The transmission internal mode switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The 4 inputs to the TCM indicate the position of the transmission range selector. The input voltage level at the TCM is high, B+, when the IMS is open and low when the switch is closed to ground. The 4 input parameters represented are Signals A, B, C and P - Parity. Refer to Transmission Internal Mode Switch Logic .

If the TCM detects that IMS Signal C is high while the vehicle is being driven in a forward gear, then DTC P1826 sets. DTC P1826 is a type B DTC.

1. No VSS DTCs P0722 or P0723.
2. Vehicle speed is 15 km/h (9 mph) or greater.
3. Engine torque is 50 N.m (37 lb ft) or greater.
4. DTC P1826 has not passed this key cycle.

The TCM detects IMS Signal C is high, while the gear ratio indicates first, second, third or fourth gear for 60 seconds.

1. The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the consecutive trip in which the Conditions for Setting the DTC are met.
2. The TCM commands maximum line pressure.
3. The TCM freezes transmission adaptive functions.
4. The TCM assumes D4 for shifting.
5. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
6. The TCM stores DTC P1826 in TCM history during the consecutive trip in which the Conditions for Setting the DTC are met.

1. A scan tool can clear the DTC.
2. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
3. The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

The number below refers to the step number on the diagnostic table.

1. 3: This step tests the integrity of the engine harness and TCM by checking for the Signal C state change from HI to LOW. A LOW signal indicates the fault is either in the internal transmission harness or the switch. A HI signal indicates the fault is either in the engine harness or the TCM.

DTC P1826 (3.6L)

Scheme 119

Ignition voltage is provided to the torque converter clutch pulse width modulation (TCC PWM) solenoid valve. The PCM controls the solenoid with a negative duty cycle in order to control application and release of the TCC. When the solenoid is commanded OFF, the PCM senses high voltage. When the solenoid is commanded ON, the PCM senses low voltage.

If the PCM detects a continuous open, short to ground or short to voltage in the TCC PWM valve circuit, then DTC P1860 sets. DTC P1860 is a type B DTC.

1. The engine speed is greater than 500 RPM for 5 seconds and not in fuel cut off.
2. The TCC duty cycle is 10 percent or less or 70 percent or greater.

DTC P1860 sets when one of the following conditions exists for at least 5 seconds

1. The PCM commands the solenoid to greater than 70% duty cycle and the voltage feedback remains high, B+.
2. The PCM commands the solenoid to less than 10% duty cycle and the voltage feedback remains low, 0 volts.

1. The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
2. The PCM inhibits TCC.
3. The PCM inhibits 4th gear if the transmission is in Hot Mode.
4. The PCM freezes transmission adaptive functions.
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
6. The PCM stores DTC P1860 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

Conditions for Clearing the MIL/DTC

1. The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

Diagnostic Aids

Ensure the wiring harness is not stretched too tightly or other components are pressing on the A/T inline 20-way connector body. Also inspect for proper clearance to any other components and wiring. Refer to Intermittent Conditions in Engine Controls - 3.4L.

The number below refers to the step number on the diagnostic table.

1. 2: A short to ground in the power feed circuit to the solenoid ahead of the splice would open the fuse and set DTCs for other solenoids on the same circuit. An open in the same circuit would not open the fuse but would set the other DTCs.

DTC P1860 (3.4L)

Scheme 120

The TCC release switch is part of the transmission fluid pressure (TFP) manual valve position switch. The TFP manual valve position switch is mounted to the transmission valve body. The TCC release switch is normally-closed.

The switch signals the PCM that the TCC is released. This is accomplished by torque converter release fluid pressure acting on the switch contact which opens the circuit. When the circuit voltage is high, the PCM recognizes that the TCC is no longer engaged.

If the PCM determines that the TCC release switch is open indicating that the TCC is not applied and the TCC slip speed indicates that the TCC is applied, then DTC P1887 sets. DTC P1887 is a type B DTC.

1. No ISS sensor DTC P0716 or P0717.
2. No TCC PWM solenoid valve DTC P1860.
3. The engine speed is greater than 500 RPM for 5 seconds and not in fuel cut off.
4. The TCC is commanded ON.
5. The TCC slip speed is -20 to +60 RPM.
6. The engine torque is 41-407 N.m (30-300 lb ft).

DTC P1887 sets when the following condition occurs twice in a single trip

The TCC release pressure switch is open indicating release pressure present for 6 seconds continuous.

1. The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
2. The PCM inhibits TCC.
3. The PCM inhibits 4th gear if the transmission is in Hot Mode.
4. The PCM freezes transmission adaptive functions.
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
6. The PCM stores DTC P1887 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

1. The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

1. Do not replace the torque converter for this condition, refer to the «Torque Converter Replacement Guide»(/buick/rendezvous/i-2001-2007/remont/automatic-trans/#automatic-transaxle-4t65-ediagnostics-troubleshooting__torque-converter-replacement-guide) for other concerns.
2. Ensure the wiring harness is not stretched too tightly or other components are pressing on the A/T inline 20-way connector body. Also inspect for proper clearance to any other components and wiring. Refer to «Intermittent Conditions»(/buick/rendezvous/i-2001-2007/remont/testing-diagnostics/#engine-controls-34l-troubleshooting__intermittent-conditions) in Engine Controls - 3.4L.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: This step tests the PCMs ability to recognize a grounded circuit.
2. 4: A short to ground in this circuit would set DTC P0742.
3. 5: A short to ground in this circuit would set DTC P0742.

DTC P1887 (3.4L)

Scheme 121

The TCC release switch is part of the transmission fluid pressure (TFP) manual valve position switch. The TFP manual valve position switch is mounted to the transmission valve body. The TCC release switch is normally-closed.

The switch signals the TCM that the TCC is released. This is accomplished by torque converter release fluid pressure acting on the switch contact which opens the circuit. When the circuit voltage is high, the TCM recognizes that the TCC is no longer engaged.

If the TCM determines that the TCC release switch is open indicating that the TCC is not applied and the TCC slip speed indicates that the TCC is applied, then DTC P1887 sets. DTC P1887 is a type B DTC.

1. No ISS sensor DTC P0716 or P0717.
2. No TCC PWM solenoid valve electrical DTCs P2763 or P2764.
3. The engine speed is greater than 500 RPM for 5 seconds and not in fuel shut off.
4. The TCC is commanded ON.
5. The transmission fluid temperature is 20-130°C (68-266°F).
6. The TCC slip speed is -20 to +60 RPM.
7. The engine torque is greater than 50 N.m (37 lb ft).

DTC P1887 sets when the following condition occurs twice in a single trip

The TCC release pressure switch is open indicating release pressure present for 6 seconds continuous.

1. The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
2. The TCM inhibits TCC.
3. The TCM inhibits 4th gear if the transmission is in Hot Mode.
4. The TCM freezes transmission adaptive functions.
5. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Freeze Frame and Failure Records.
6. The TCM stores DTC P1887 in TCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

1. The ECM turns OFF the MIL after the third consecutive trip in which the TCM does not send an MIL illumination request.
2. A scan tool can clear the MIL/DTC.
3. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

1. Do not replace the torque converter for this condition, refer to the «Torque Converter Replacement Guide»(/buick/rendezvous/i-2001-2007/remont/automatic-trans/#automatic-transaxle-4t65-ediagnostics-troubleshooting__torque-converter-replacement-guide) for other concerns.
2. Ensure the wiring harness is not stretched too tightly or other components are pressing on the A/T inline 20-way connector body. Also inspect for proper clearance to any other components and wiring. Refer to «Intermittent Conditions»(/buick/rendezvous/i-2001-2007/remont/testing-diagnostics/#engine-controls-36l-ly7-troubleshooting__intermittent-conditions) in Engine Controls - 3.6L.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: This step tests the TCMs ability to recognize a grounded circuit.
2. 4: A short to ground in this circuit would set DTC P0742.
3. 5: A short to ground in this circuit would set DTC P0742.

DTC P1887 (3.6L)

Scheme 122

Ignition voltage is provided to the torque converter clutch pulse width modulation (TCC PWM) solenoid valve. The TCM controls the solenoid with a negative duty cycle in order to control application and release of the TCC. When the solenoid is commanded OFF, the TCM senses high voltage. When the solenoid is commanded ON, the TCM senses low voltage.

DTC P2763 sets if the TCM detects a voltage that is outside of the calibration limits. DTC P2763 is a type B DTC.

The ignition is ON.

DTC P2763 sets when one of the following conditions exists for at least 5 seconds

1. The TCM commands the solenoid to greater than 90% duty cycle and the voltage feedback remains high, B+.
2. The TCM commands the solenoid to less than 10% duty cycle and the voltage feedback remains low, 0 volts.

1. The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
2. The TCM commands maximum line pressure.
3. The TCM forces TCC OFF.
4. The TCM inhibits 4th gear if the transmission is in Hot Mode.
5. The TCM freezes transmission adaptive functions.
6. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Freeze Frame and Failure Records.
7. The TCM stores DTC P2763 in TCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

1. The ECM turns OFF the MIL after the third consecutive trip in which the TCM does not send an MIL illumination request.
2. A scan tool can clear the MIL/DTC.
3. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

Ensure the wiring harness is not stretched too tightly or other components are pressing on the A/T inline 20-way connector body. Also inspect for proper clearance to any other components and wiring. Refer to Intermittent Conditions in Engine Controls - 3.6L.

The number below refers to the step number on the diagnostic table.

1. 2: A short to ground in the power feed circuit to the solenoid ahead of the splice would open the fuse and set DTCs for other solenoids on the same circuit. An open in the same circuit would not open the fuse but would set the other DTCs.

DTC P2763 (3.6L)

Ignition voltage is provided to the torque converter clutch pulse width modulation (TCC PWM) solenoid valve. The TCM controls the solenoid with a negative duty cycle in order to control application and release of the TCC. When the solenoid is commanded OFF, the TCM senses high voltage. When the solenoid is commanded ON, the TCM senses low voltage.

DTC P2764 sets if the TCM detects an open or short to ground in the TCC PWM solenoid valve circuit. DTC P2764 is a type B DTC.

The system voltage is 8-18 volts.

DTC P2764 sets when one of the following conditions exists for at least 5 seconds

1. The TCM commands the solenoid to greater than 90% duty cycle and the voltage feedback remains high, B+.
2. The TCM commands the solenoid to less than 10% duty cycle and the voltage feedback remains low, 0 volts.

1. The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
2. The TCM commands maximum line pressure.
3. The TCM forces TCC OFF.
4. The TCM inhibits 4th gear if the transmission is in Hot Mode.
5. The TCM freezes transmission adaptive functions.
6. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Freeze Frame and Failure Records.
7. The TCM stores DTC P2764 in TCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

1. The ECM turns OFF the MIL after the third consecutive trip in which the TCM does not send an MIL illumination request.
2. A scan tool can clear the MIL/DTC.
3. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

Ensure the wiring harness is not stretched too tightly or other components are pressing on the A/T inline 20-way connector body. Also inspect for proper clearance to any other components and wiring. Refer to Intermittent Conditions in Engine Controls - 3.6L.

The number below refers to the step number on the diagnostic table.

1. 2: A short to ground in the power feed circuit to the solenoid ahead of the splice would open the fuse and set DTCs for other solenoids on the same circuit. An open in the same circuit would not open the fuse but would set the other DTCs.

DTC P2764 (3.6L)

Scheme 123

The controller area network (CAN) consists of two separate conductors between the ECM and the transmission control module (TCM). Each module sends information by toggling the circuits high or low to produce pulse width signals, which the other modules decode.

The CAN data stream contains information such as status messages for relevant operating parameters, device requests and acknowledgments, and state-of-health messages.

When the TCM has not received ECM data for a specified amount of time, then DTC U2105 will set. DTC U2105 is a type B DTC.

The ignition is ON.

The TCM has not received ECM messaging for 1 second.

1. The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the second consecutive drive trip in which the Conditions for Setting the DTC are met.
2. The TCM commands maximum line pressure.
3. The TCM forces the TCC ON at maximum capacity.
4. The TCM freezes transmission adaptive functions.
5. Torque management is inhibited.
6. At the time of the first failure, the TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as a Failure Record.
7. At the time of the second failure, the ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as a Freeze Frame.
8. The TCM stores DTC U2105 in TCM history.

1. The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.
2. A scan tool can clear the MIL/DTC.
3. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
4. The TCM cancels the default actions when the ignition is OFF long enough in order to power down the TCM.

This DTC sets when a communication fault exists between the ECM and the TCM. Inspect for DTCs U 2100, U 2104 and U 2106. If any of these DTCs are present, diagnose them first.

The number below refers to the step number on the diagnostic table.

1. 2: Performing this step verifies that an operational abnormality did not take place during TCM power-up, such as Electromagnetic Interference (EMI).

DTC U2105 (3.6L)

See also:
• Transmission Internal Mode Switch Logic
• Diagnostic System Check - Engine Controls
• Intermittent Conditions
• Testing for Short to Ground
• Wiring Repairs
• Wiring Harness Replacement
• Powertrain Control Module (PCM) Replacement
• Diagnostic Trouble Code (DTC) List
• Diagnostic System Check - Engine Controls
• Intermittent Conditions
• Diagnostic Trouble Code (DTC) List
• Automatic Transmission Inline 20-Way Connector End View (3.4L)
• Testing for Continuity
• Circuit Testing
• Circuit Protection - Fuses
• Torque Converter Replacement Guide
• Testing for a Short to Voltage
• Engine Control Module (ECM) Replacement