4L80-E / 4L85-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 2-3 Shift Solenoid (SS) valve controls fluid acting on the 2-3 shift valve. The 2-3 SS valve is a normally-open exhaust valve used with the 1-2 SS valve in order to allow tour different shifting combinations. The 2-3 SS valve attaches to the control valve body within the transmission. The ignition voltage goes directly to the 2-3 SS valve. The Vehicle Control Module (VCM) controls the 2-3 SS valve by providing a ground path.

If the VCM detects a continuous open or short in the 2-3 SS valve circuit or the 2-3 SS valve, then DTC P0758 sets. DTC P0758 is a type C DTC. For California emissions vehicles, DTC P0758 is a type A DTC.

CONDITIONS FOR RUNNING THE DTC
^ The system voltage is 10-16 volts.
^ The engine is running more than 475 RPM for more than 7 seconds.

CONDITIONS FOR SETTING THE DTC
The above conditions are met and either of the following conditions occur for 4.3 out of 5 seconds.
^ The VCM commands the 2-3 SS valve ON, and the voltage input remains high (B+).
^ The VCM commands the 2-3 SS valve OFF, and the voltage input remains low (0 volts).

ACTION TAKEN WHEN THE DTC SETS
^ The VCM illuminates the Malfunction Indicator Lamp (MIL) for California emission vehicles.
^ The VCM commands an immediate landing to second gear.
^ The VCM commands maximum line pressure.
^ The VCM freezes shift adapts form 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 P0758 in VCM history.

CONDITIONS FOR CLEARING THE MIL/DTC
^ For California emissions, 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.
^ For California emissions, the VCM clears the DTC from VCM history if the vehicle completes 40 consecutive warm-up cycles without an emission related diagnostic fault occurring.
^ For Federal emissions, the VCM clears the DTC from VCM history if the vehicle completes 40 consecutive warm-up cycles without a non-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
^ First diagnose and clear any engine DTCs or TP sensor codes that are present. Then inspect for any transmission DTCs that may have reset.
^ Refer to Shift Solenoid Valve State and Gear Ratio table.
^ Inspect the connectors at the VCM, the AT wiring harness 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 the function of the 2-3 SS valve and the internal wiring harness.
5. This step tests the power to the 2-3 SS valve from the ignition through the fuse.
10. This step measures the resistance of the 2-3 SS valve.