P1860

Circuit Description
The Torque Converter Clutch Pulse Width Modulation Solenoid Valve (TCC PWM Sol. Valve) controls the fluid acting on the converter clutch valve. The converter clutch valve controls the application and the release of the TCC. The PCM controls the TCC PWM Sol. Valve by varying its duty cycle (ON/OFF time) from 0-100%, thus modulating the feed pressure to the converter clutch regulator valve. At 0% duty cycle, the torque converter clutch applies at maximum capacity. At 100% duty cycle the clutch applies at minimum capacity.

Ignition voltage is applied through a fused circuit 1039 to the TCC PWM solenoid. The Output Driver Module (ODM), within the PCM provides the ground path for the circuit.

When the PCM detects a continuous open or short to ground in the TCC PWM circuit then DTC P1860 sets. DTC P1860 is a type A DTC.

Conditions for Setting the DTC
^ System voltage is 10-16 volts.
^ The engine speed is more than 500 RPM.
^ Not in fuel shut off.
^ When the PCM commands duty cycle below 10% or above 90%, the PCM detects a signal voltage on circuit 418 outside the calibrated limits.
All of the above conditions are met for 5 seconds.

Action Taken When the DTC Sets
^ The PCM illuminates the Malfunction Indicator Lamp (MIL).
^ The PCM inhibits TCC operation.
^ The PCM inhibits 4th gear if the transmission is in the hot mode.

Conditions for Clearing the MIL/DTC
^ The PCM turns OFF the MIL after three consecutive trips without a failure reported.
^ A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.
^ The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM.

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

Test Description
The numbers below refer to the step numbers on the diagnostic table.
3. This step isolates the engine harness from the transmission harness.
5. This step verifies that engine harness circuit 418 is not open or shorted to power.
8. This step verifies that the TOO PWM solenoid is not shorted across its windings or open, or the transmission harness shorted or open.