P1860

Diagnostic Chart:

Wiring Diagram:

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 clutch valve controls the application and the release of the TCC. When you command the TCC PWM Sol. Valve OFF, the Powertrain Control Module (PCM) receives high voltage. When you command the TCC PWM Sol. Valve ON, the PCM receives low voltage.

DTC PI 860 sets anytime the received voltage is outside of the calibration limits. DTC P1860 is a type A DTC.

Conditions for Setting the DTC

^ The system voltage is 10-16 volts.

^ The engine speed is more than 500 RPM for 5 seconds.

^ The transmission is in first gear.

^ Not in fuel shut off

^ The PCM commands the solenoid to greater than 90% and circuit 418 voltage remains low (0.0 volts).

^ The PCM commands the solenoid to less than 10% and circuit 418 voltage remains high (B+).

^ All conditions are met for 5 seconds.

Action Taken When the DTC Sets

^ The PCM inhibits TCC operation.

^ The PCM inhibits 4th gear if the transmission is in the hot mode

^ The PCM disables shift adapts.

^ The PCM illuminates the Malfunction Indicator Lamp (MIL).

Conditions for Clearing the MIL/DTC

^ The PCM turns OFF the MIL after three consecutive ignition cycles 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

^ Inspect the wiring for poor electrical connections at the PCM. Inspect the wiring at the transmission 20-way connector. Inspect the wiring at the 2-way TCC connector. Look for the following problems:

- A bent terminal

- A backed out terminal

- A damaged terminal

- Poor terminal tension

- A chafed wire

- A broken wire inside the insulation

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

^ Ensure that the transmission fluid is at the proper level.

Test Description

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

6. This step isolates the engine harness from the transmission harness. Use a test lamp in order to verify the circuitry.

8. This step verifies that circuit 418 is not open or shorted to power.

12. This step verifies that the TCC PWM solenoid is not shorted across its windings or increased its resistance.

19. Because of the harsh conditions inside the transmission, repairing the A/T Wiring Harness is not acceptable. You must replace the A/T Wiring Harness.