P1864

CIRCUIT DESCRIPTION

In conjunction with the Torque Converter Clutch Pulse Width Modulation Solenoid Valve (TCC PWM Sol. Valve), the Torque Converter Clutch Solenoid Valve (TCC Sol. Valve) controls the fluid acting on the TCC converter clutch valve. This controls the TCC apply and release. The PCM monitors the throttle position, the vehicle speed and other inputs in order to determine when to energize the TCC Sol. Valve. Circuit 639 supplies ignition voltage directly to the TCC Sol. Valve. The PCM controls the TCC Sol. Valve by providing the ground path through circuit 422. When you command the TCC Sol. Valve OFF, the PCM receives high voltage. When you command the TCC Sol. Valve ON, the PCM receives low voltage.

When the PCM detects low voltage when the TCC Sol. Valve is commanded OFF or high voltage when the TCC Sol. Valve is commanded ON, then DTC P1864 sets. DTC P1864 is a type A DTC.

CONDITION FOR SETTING THE DTC

^ No System Voltage Malfunction DTC P0560.

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

^ Not in fuel shut off.

^ No open or short to ground exists for 4.3 seconds.

ACTION TAKEN WHEN THE DTC SETS

^ The PCM inhibits TCC operation.

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

^ 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 7-way connector. Look 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.

^ When diagnosing for an intermittent short or open condition, 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.

6. This Step isolates the fault between the engine harness and the transmission harness.

8. This Step verifies that circuit 422 is not open or shorted to power.

12. This Step verifies that the TCC Sol. Valve is not shorted across its windings or increased its resistance.