DTC 79

Diagnostic Chart:

Diagnostic Chart (Cont'd):

Circuit Schematic:

TCC ACTUATOR CIRCUIT GROUNDED/OPEN
The Torque Converter Clutch is applied when circuit 422 is grounded at the PCM. When the PCM opens the circuit the voltage is monitored at terminal J3E14 to check for proper circuit conditions.

INFORMATION FLAG PARAMETERS
Information flag 79 is set when the PCM has detected the following condition twice per ignition cycle.
^ Voltage monitored at terminal J3E14 (circuit 422) is less than 2 - 2.5 volts when the actuator is switched off 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 TCC fuse is OK, check for battery voltage on fuel pump relay side of fuse with engine running or PCM in diagnostic mode.
3. This step checks for a ground in circuit 1526A. A ground in circuit 1526A will cause the TCC fuse to fail and set information flag 79.
4. A faulty actuator or connector plate could have blown the TRS 2/TCC fuse. This step checks for low resistance.
5. An open in circuit 1526A will cause information flag 79 to set. Check circuit 1526A for opens.
6. This step will determine if fault is in the circuit to PCM or in the actuator or connector plate.
7. This step will determine if the fault is in the actuator or in the connector plate.
8. An open or a ground in circuit 422 will set information flag 79. This step checks circuit 422 for opens or grounds.

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.
^ This information flag or a DTC 25 - No TCC may set because of a poor electrical connection at either the PCM, actuator connector plate or UHJB terminals. Wiggling connectors while performing an actuator quick test may help isolate the problem area.

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.
^ An open circuit will probably also set a DTC 25 - No TCC.
^ A grounded circuit 472 will probably also set a DTC 26 TCC Stuck On.

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