P1860

Diagnostic Chart:

Diagnostic Chart (cont'd):

Wiring Diagram:

Circuit Description
The TCC Pulse Width Modulated (PWM) Solenoid Valve controls fluid acting on the converter clutch valve, which then controls TCC apply and release. The TCC PWM Sol. Valve attaches to the control valve body within the transmission. Ignition voltage goes directly to the TCC PWM Sol. Valve. The VCM controls the TCC PWM Sol. Valve by providing a ground path on circuit 418. The current flows through the TCC PWM Sol. Valve coil according to the duty cycle (percentage of ON time). The TCC PWM Sol. Valve provides a smooth engagement of the torque converter clutch by operating on a duty cycle percent of ON time.

When the VCM detects a continuous open or short in the TCC PWM Sol. Valve circuit or the TCC PWM Sol. Valve, then DTC P1860 sets. DTC P1860 is a type D DTC. For California emission vehicles DTC P1850 is a type A DTC.

Conditions for Setting the DTC

^ No system voltage DTC P0560.
^ The ignition is ON.
^ No shift solenoid DTCs P0751, P0753, P0756, or P0758.
^ The VCM commands the solenoid to 0% and the voltage remains low (zero volts).
^ The brake switch is OFF.
^ All conditions are met for 5 seconds.

Action Taken When the DTC Sets

^ The VCM inhibits TCC engagement.
^ The VCM inhibits 4th gear.
^ The VCM freezes shift adapts from being updated.
^ The VCM illuminates the Malfunction Indicator Lamp.

Conditions for Clearing the DTC

^ For California emissions vehicles, the VCM turns OFF the Malfunction Indicator Lamp (MIL) after three consecutive ignition cycles without a failure reported.
^ A scan tool can clear the DTC from the VCM history. The VCM clears the DTC from the VCM history if the vehicle completes 40 warm-up cycles without a failure reported.
^ The VCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the VCM.

Diagnostic Aids

^ Inspect the wiring for poor electrical connections at the VCM. Inspect the wiring for poor electrical connections at the transmission 20-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.
^ First diagnose and clear any engine DTCs or TP Sensor codes that are present. Then inspect for any transmission DTCs that may have reset.

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

4. This step tests for voltage to the TCC PWM Sol. Valve.
6. This step tests the ability of the VCM and wiring to control the ground circuit.
8. This step tests the resistance of the TCC PWM Sol. Valve and the internal wiring harness.