4L60-E / 4L65-E Automatic Transmission

Diagnostic Chart(Part 1 Of 3):

Diagnostic Chart (Part 2 Of 3):

Diagnostic Chart (Part 3 Of 3):

Schematic:

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 1020. The Vehicle Control Module (VCM) 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 TCC by operating during a duty cycle percent of ON time.

When the VCM 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 10-19 volts.
^ The engine speed is greater than 450 RPM for 5 seconds.
^ The engine is not in fuel cutoff.
^ The VCM commands first gear.
^ The TCC duty cycle is less than 10% or greater than 90%.

CONDITIONS FOR SETTING THE DTC
DTC P1860 sets if one of the following conditions occurs for 5 seconds:

Condition 1
The VCM commands the solenoid ON (90%) and the voltage feedback remains high (B+).

Condition 2
The VCM commands the solenoid OFF (0%) and the voltage feedback remains low (0 volt).

ACTION TAKEN WHEN THE DTC SETS
^ The VCM illuminates the Malfunction Indicator Lamp (MIL).
^ The VCM inhibits TCC engagement.
^ The VCM inhibits 4th gear if the transmission is in hot mode.
^ The VCM freezes shift adapts from being updated.
^ The VCM records the operating conditions when the Conditions for Setting the DTC are met. The VCM stores this information as Freeze Frame and Failure Records.
^ The VCM stores DTC P1860 in VCM history.

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

DIAGNOSTIC AIDS
^ Inspect the connectors at the VCM, the TCC PWM solenoid valve and all other circuit connecting points for an intermittent condition. Refer to Testing for Intermittent and Poor Connections in Diagrams.
^ Inspect the circuit wiring for an intermittent condition. Refer to Testing for Electrical Intermittents in Diagrams.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
4. This step tests for voltage to the solenoid.
5. This step tests the ability of the VCM and wiring to control the ground circuit.
7. This step tests the resistance of the TCC PWM solenoid valve and the Automatic Transmission (AT) wiring harness assembly.