P1860

Circuit Description
The Torque Converter Clutch Pulse Width Modulation (TCC PWM) solenoid valve is a normally closed solenoid used to control the apply and release of the converter clutch. The PCM operates the solenoid with a negative duty cycle. When vehicle operating conditions are appropriate to apply the TCC, the PCM immediately increases the duty cycle to approximately 42%. The PCM then ramps the duty cycle to approximately 90% to achieve full TCC apply pressure. When the solenoid is commanded OFF, the PCM senses low voltage. When the solenoid is commanded ON, the PCM senses high voltage.
When the PCM detects a continuous open, short to ground or short to power in the TCC PWM solenoid valve circuit, then DTC P1860 sets. DTC P1860 is a type A DTC.

Conditions for Running the DTC
^ The system voltage is 8-18 volts.
^ The engine has been running for more than 5 seconds, and is not in fuel cut off.

Conditions for Setting the DTC
^ The TCC PWM solenoid valve duty cycle is less than 10% or greater than 90%.
^ The PCM detects an open, short to ground or a short to power on the TCC PWM solenoid valve circuit within 5 seconds.

Action Taken When the DTC Sets
^ The PCM illuminates the Malfunction Indicator Lamp (MIL).
^ The PCM inhibits TCC engagement.
^ The PCM freezes shift adapts from being updated.
^ The PCM stores DTC P1860 in PCM history.

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 20-way connector and the TCC PWM solenoid valve 2-way connector 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
^ Ensure that the transmission fluid is at the proper level.
^ When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the lest equipment for a change.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. DTCs P0753 and P0758 set if the power circuit is open.
11. This step tests the PCM and the wiring to the transmission 20-way connector.
14. This step tests circuit 418 for a short to battery power.
16. This step tests the circuit for correct resistance.