4L80-E / 4L85-E Automatic Transmission

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 four 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 powertrain control module (PCM) controls the 2 - 3 SS valve by providing the ground path through CKT 1223.
If the PCM 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 D DTC. For California emissions vehicles, DTC P0758 is a type A DTC.

Conditions for Running the DTC
^ The system voltage is 8.0-18.0 volts.
^ The engine is running more than 300 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 PCM commands the 2 - 3 SS valve ON, and the voltage input remains high (B+).
^ The PCM commands the 2 - 3 SS valve OFF, and the voltage input remains low (0 volts).

Action Taken When the DTC Sets
^ The PCM illuminates the malfunction indicator lamp (MIL) for California emission vehicles.
^ The PCM commands an immediate landing to second gear.
^ The PCM commands maximum line pressure.
^ The PCM freezes shift adapts form being updated.
^ The PCM stores DTC P0758 in PCM history.

Conditions for Clearing the MIL/DTC
^ For California emissions, the PCM 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 PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without an emission related diagnostic fault occurring.
^ For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without a non-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, massage the wiring harness while watching the test equipment for a change.
^ 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.

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.
7. This step tests the ability of the PCM and the wiring to control the ground circuit.
10. This step measures the resistance of the automatic transmission (A/T) wiring harness assembly and the 2 - 3 SS valve.