P1860

WITH 4L60-E AUTOMATIC TRANSMISSION

DTC P1860 TCC PWM Solenoid Circuit - Electrical Diagnostic Chart:

TCC PWM Solenoid Circuit - Electrical Wiring Schematic:

CIRCUIT DESCRIPTION
The Vehicle Control Module-A (VCM-A) supplies a ground allowing current to flow through the solenoid coil according to the duty cycle (percentage of "ON" and "OFF" time), This current flow through the solenoid coil creates a magnetic field that magnetizes the solenoid core. The magnetized core attracts the check ball to seat against spring pressure. This blocks the exhaust for the Torque Converter Clutch (TCC) signal fluid and allows 2-3 drive fluid to feed the TCC signal circuit. The TCC signal fluid pressure acts on the TCC regulator valve to regulate line pressure and to apply fluid pressure to the torque converter clutch shift valve. When the TCC shift valve is in the apply position, regulated apply fluid pressure is directed through the TCC valve to apply the torque converter clutch. The TCC Pulse Width Modulation (PWM) solenoid is used in conjunction with the TCC solenoid to regulate fluid to the torque converter, The TCC PWM solenoid is attached to the valve body within the transmission. DTC Type (D).

DTC P186O WILL SET WHEN
- The VCM-A commands the solenoid "ON" and voltage remains high (B+).
or
- The VCM-A commands the solenoid "OFF" and voltage remains low (zero volts).
- All conditions met for four seconds.

ACTION TAKEN (VCM-A will default to)
- Inhibit TCC operation.
- Inhibit 4th gear operation if in hot mode.
- Will not turn on MIL.

DTC P1860 WILL CLEAR DEFAULT ACTION WHEN
The fault condition(s) no longer exist and the ignition switch is cycled "OFF" for five seconds, then "ON".

DTC P1860 WILL PASS WHEN
- VCM-A commands the solenoid "ON" and voltage drops to 0 volts.
or
- VCM-A commands the solenoid "OFF" and voltage increases to (B+).
- All enabling criteria are met for four seconds.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test will check if the VCM-A is commanding the TCC solenoid "ON."
2. This test will check for voltage to the solenoid.

DIAGNOSTIC AIDS
Check all connections at the transmission pass-thru connector.
If they are OK refer to Intermittents.