P1860

Circuit Description

Ignition voltage is provided to the torque converter clutch pulse width modulation (TCC PWM) solenoid valve. The PCM controls the ON and OFF time of the solenoid by providing a ground through the output driver module (ODM) B. The PCM uses a PWM duty cycle, in order to control application and release of the TCC. When the solenoid is commanded OFF, the PCM senses high volts. When the solenoid is commanded ON, the PCM senses low volts.

If the PCM detects voltage limits that do not meet the calibration, then DTC P1860 sets. DTC P1860 is a Type A DTC.

Conditions for Running the DTC

^ No ODM DTC P1650.
^ The engine run time is greater than 5 seconds.
^ The TCC PWM solenoid valve duty cycle is less than 10% or greater than 85%.

Conditions for Setting the DTC

The PCM detects an open, a short to ground, or a short to power on the TCC PWM solenoid valve circuit within 5 seconds.

Action Taken When the DTC Sets

^ The PCM illuminates the malfunction indicator lamp (MIL).
^ SERVICE ENGINE SOON, SERVICE TRANSMISSION displays on the driver information center (DIC).
^ The PCM inhibits TCC engagement.
^ The PCM inhibits 4th gear when the transmission is in hot mode.
^ The PCM stores DTC P1860 in PCM history.

Conditions for Clearing the MIL/DTC

^ The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
^ A scan tool clears the DTC from PCM history.
^ The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
^ The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

Diagnostic Aids

^ Inspect the wiring at the PCM, the transmission 20-way connector, the TCC PWM solenoid valve 2-way connector, and all other circuit connecting points for the following conditions:
- A backed out terminal
- A damaged terminal
- Reduced terminal tension
- A chafed wire
- A broken wire inside the insulation
- Moisture intrusion
^ Ensure that the transmission fluid is at the proper level.
^ When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.

Test Description

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

3. This step verifies power to terminal U of the engine wiring harness. If the test lamp lights, inspect circuit 422 for a short to ground.
5. This step uses the scan tool in order to cycle the TCC PWM solenoid valve ON and OFF.
10. This step verifies that the TCC PWM solenoid valve is within resistance specifications.