Transmission Controls With PCM

Diagnostic Chart:

Wiring Diagram:

The master enable relay provides battery voltage to all actuator circuits and the PCM. On 1991 and 1992 vehicles the relay is normally open and is closed when circuit 3G is connected to battery voltage through the ignition switch and circuit 1531 is grounded at the PCM. When the relay closes, battery voltage is fed into circuit 999 to supply all actuator fuses and the PCM hold mode fuse,

INFORMATION FLAG PARAMETERS

Information flag 43 is set when the PCM has detected the following conditions after the relay has been switched on electrically by the PCM.


^ Engine is running.


^ Hold mode voltage monitored at terminal J3E13 on the PCM below 0.9 volts.


^ Voltage to all five actuators, monitored at terminals J3E14, J3E10, J3F3, J3F2, and J3F1 on the PCM below 0.9 volts.


^ ignition voltage above 9.5 volts.


TEST DESCRIPTION

Numbered steps below refer to numbered steps on chart.


1. This step verifies problem is still present.


2. If relay coil fails or contacts fail open, information. Flag 43 will set. This test checks for faulty relay. Any relay in the UHJB could be used to perform this test.

3. If circuit 1531 is open, information flag 43 will set. This test checks circuit 1531 for any faults.


4. If circuit 999 is grounded or open, information flag 43 will set. This test checks circuit 999 for any faults.


5. If voltage is absent from either side of relay information flag 43 will set. This test checks for voltage to master enable relay coil and contact sides.


DIAGNOSTIC AIDS

When attempting to diagnose an intermittent problem use the Scan tool* to review supplemental diagnostic information. The supplemental data can be used to duplicate a problem.


Check the tightness of the female terminal grip with a spare male terminal.


When the PCM detects a fault in the circuit (open, ground short) the PCM will open the circuit internally to protect the circuit.


^ This information flag will cause transaxle to start out in 4th gear.