P1860

Circuit Description

The torque converter clutch pulse width modulation (TCC PWM) solenoid valve controls the fluid acting on the converter clutch valve. The converter clutch valve controls the TCC application and release. The solenoid attaches to the control valve body within the transmission. The solenoid receives ignition voltage through circuit 239. The powertrain control module (PCM) controls the solenoid by providing a ground path on circuit 418. Current flows through the solenoid coil according to the duty cycle (percentage of ON and OFF time). The TCC PWM solenoid valve provides a smooth engagement of the torque converter clutch by operating during a duty cycle percent of ON time.

When the PGM detects a continuous open or short to ground in the TCC PWM solenoid valve circuit or the TCC PWM solenoid valve, then DTC P1860 sets. DTC P1860 is a type B DTC.

Conditions for Running the DTC

^ The system voltage is 9-18 volts.
^ The engine speed is greater than 450 RPM for 5 seconds.
^ The engine is not in fuel cutoff.
^ The PCM commands first gear.
^ The TCC duty cycle is less than 10% or greater than 90%.

Conditions for Setting the DTC

DTC P1860 sets if either of the following conditions occurs for 5 seconds:

^ The PCM commands the solenoid ON (90%) and the voltage input remains high (B+).
^ The PCM commands the solenoid OFF (0%) and the voltage input remains low (0 volt).

Action Taken When the DTC Sets

^ The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the conditions for setting the DTC are met.
^ The PCM inhibits TCC engagement.
^ The PCM inhibits 4th gear if the transmission is in hot mode.
^ The PCM freezes shift adapts from being updated.
^ The PCM stores DTC P1860 in PCM history during the second consecutive trip in which the conditions for setting the DTC are met.

Conditions for Clearing the MIL/DTC

^ The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
^ A scan tool clears the DTC from PCM history.
^ The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

Diagnostic Aids

^ Inspect the wiring at the PCM, the transmission connector and all other circuit connecting points for the following conditions:
- A backed out terminal
- A damaged terminal
- Reduced terminal tension
- A chafed wire
- A broken wire inside the insulation
- Moisture intrusion
- Corrosion
^ 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.

4. This step tests for voltage to the solenoid.
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 solenoid valve and the automatic transmission (A/T) wiring harness assembly.