Transmission Controls With PCM

Diagnostic Chart:

Circuit Schematic:

4TH GEAR ACTUATOR CIRCUIT SHORTED TO VOLTAGE
4th clutch is applied when circuit 898 is opened at the PCM. When the PCM grounds the circuit the voltage is monitored at terminal J3E10 to check for proper circuit conditions.

INFORMATION FLAG PARAMETERS
Information flag 77 is set when the PCM has detected the following condition twice per ignition cycle.
- Voltage monitored at terminal J3E10 (circuit 898) is greater than 2 - 2.5 volts when the 4th gear actuator is switched on electrically by the PCM.

TEST DESCRIPTION
Numbered steps below refer to numbered steps on chart.
1. This step verifies problem is still present.
2. If the actuator, connector plate, or circuit 1223 is shorted, information flag 77 will set. This step will break down the circuit to find the source of the short.
3. If circuit 446 is shorted to voltage information flag 77 will set. This step checks circuit 898 for a short to voltage.
4. This step will determine if it is the actuator or the actuator connector plate that is shorted. An actuator is shorted internally when its resistance is one or more ohms lower than the average -- resistance of the other actuators at the same temperature.

DIAGNOSTIC AIDS
When attempting to diagnose an intermittent problem use the Scan tool[1] 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.
- Conditions that set this information flag will probably result in a DTC 78 - 4th Gear Stuck On and a DTC 25 - No TCC.

[1] Select Malfunction History from Scan tool TCM menu.