P1860

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION
The Torque Converter Clutch Pulse Width Modulation Solenoid Valve (TCC PWM Sol. 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 Powertrain Control Module (PCM) 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 and OFF 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. If the PCM detects a continuous open or short to ground in the TCC PWM Sol. Valve circuit or the TCC PWM Sol. Valve, then DTC P1860 sets. DTC P1860 is a type A DTC.

CONDITIONS FOR SETTING THE DTC
^ System voltage is 10-16.5 volts.
^ The engine is running more than 475 RPM for greater than 7 seconds.
^ No shift solenoid DTCs P0751, P0753, P0756, and P0758.
^ Commanded gear is D1.
^ All of the above conditions are met, and one of the following conditions is met for 4.3 seconds out of 5 seconds.
- The PCM commands the solenoid OFF, and the voltage remains low (zero volts).
- The PCM commands the solenoid to ON (100%) and the voltage remains high (B+).

ACTION TAKEN WHEN THE DTC SETS
^ The PCM inhibits TCC engagement.
^ The PCM inhibits 4th gear if in hot mode.
^ The PCM illuminates the Malfunction Indicator Lamp (MIL).

CONDITIONS FOR CLEARING THE DTC
1. The PCM turns OFF the MIL after three consecutive ignition cycles without a failure reported.
2. 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.
3. 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 for poor electrical connections at the transmission 20-way 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.
^ First diagnose and clear any engine DTCs 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 PCM and wiring to control the ground circuit.
8. This step tests the resistance of the TCC PWM Sol. Valve and the internal wiring harness.
12. If the internal wiring harness is open, do not repair the internal wiring harness. You must replace the Automatic Transmission Wiring Harness Assembly.