Transmission Controls With PCM

Diagnostic Chart:

Wiring Diagram:

The master enable relay provides battery voltage to all actuator circuits and the PCM when engine is running. 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

Master relay shorted is set when the PCM has detected the following conditions.


^ Engine running.


^ Voltage monitored at terminal J3E12 (Circuit 1531) is greater than 3 volts when relay is switched on electrically by PCM.


IMPORTANT: PCM will open at J3E12 if information flag 44 is set.

TEST DESCRIPTION

Numbered steps below refer to steps on trouble chart.


1. This step verifies problem is still present.


2. If relay resistance is less than 70 - 90 ohms across coil side of relay at room temperature 21°C (70°F) information flag 44 will set. This test detects faulty relay.

3. If circuit 1531 is shorted to voltage, information flag 44 will set. This test checks for voltage shorted to circuit 1531. For relay terminal identifications, refer to underhood junction block diagram, circuit 1531. For relay terminal identifications, refer to underhood junction block diagram.



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.

* Select MALF History from Scan tool TCM menu.


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 the transaxle to start out in 4th gear.