94-95 Model

This Diagnostic Trouble Code (DTC) flashes the "CHECK TRANS" Indicator and sets the Backup Mode.




Circuit Description
- The 1-2/3-4 Solenoid is a simple "ON"/"OFF" Solenoid located in the main case valve body. The Solenoid is normally the closed-type. In Second or Third Gear the Transmission Control Module (TCM) energizes the Solenoid to open a fluid inlet port. When the port is open, fluid pressure actuates the shift valve.
- The Solenoid is activated by a current. This current is produced by applying a voltage to one side (the High side) and a ground to the other side (Low side).
- The High Side Driver (HSD) is a circuit of the TCM that acts as a switch between the Solenoids and the supply voltage. The High side of the Solenoid is permanently supplied with voltage, except in Backup Mode or when Ignition is "OFF" the HSD is turned OFF.
- The TCM continually monitors the Solenoid connection to its Low Side Drivers (LSD) for either low or high voltage. The LSD is a circuit of the TCM that is used as a switch between the Solenoid and ground. When the Solenoid is commanded "ON" the TCM is switching the Solenoid to ground.
- There are two tests of the LSD: When the Engine is cranked (DTC 82) and when the Ignition is turned "ON" (DTC 31).
- When the Ignition is turned "ON", and before the Engine is cranked, the TCM activates the shift Solenoids (1-2/3-4, 2-3 and Band) to check for short circuits or open circuits. To do so the Gear is set to 4th, 3rd, 1st, 1st with band apply, 4th with no HSD. Each one of the 5 tests requires 0.15 seconds. If the Engine is cranked before the end of all tests, the remaining tests are not done.

Diagnostic Aids
- This diagnostic is an electrical test done by the TCM.

- Detection Conditions:
a. The Solenoid low side connected to TCM Terminal A2 is shorted to ground or open.
b. The test is only done when Ignition is "ON".
c. Engine Speed is less than 480 rpm (not cranked) and output speed is equal to 0 rpm.
d. The conditions need to be present for 0.15 to 1.03 seconds after Ignition Switch is "ON".

- Action After The Detection Time:
- Backup Mode.

- Recovery Conditions:
- To recover do an Ignition Cycle.




DTC 31 / Flow Chart