DTC 68

Diagnostic Chart:

Diagnostic Chart (Cont'd):

Circuit Schematic:

LINE PRESSURE ACTUATOR CIRCUIT GROUNDED/OPEN
During normal driving modes the PCM/TC adapts line pressure to prevent clutch slip and harsh shifts. This is accomplished by modulating the line pressure actuator ground (1530) to raise or lower pressure. Open circuit = high pressure, grounded circuit = low pressure. When the PCM opens the circuit the voltage is monitored to check for proper circuit conditions.

INFORMATION FLAG PARAMETERS
Information flag 68 is set when the PCM has detected the following condition at twice per ignition cycle.
- Voltage monitored at terminal J3F1 (circuit 1530) is less than 2 - 2.5 volts when the line pressure 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 TRS LP fuse is OK, check for battery voltage on fuel pump relay side of fuse with engine running or with PCM in diagnostic mode.
3. This step checks for a ground in circuit 1525. A ground in circuit 1525 will cause the TRS LP fuse to fail and set information flag 68.
4. A faulty actuator or connector plate could have blown the TRS LP fuse. This step checks for low resistance.
5. An open in circuit 1525 will cause information flag 68 to set. Check circuit 1525 for opens.
6. This step will determine if fault is in the circuit to the PCM, or in the actuator or connector plate.
7. This step will determine if the fault is in the actuator or the connector plate.
8. An open or a ground in circuit 1530 will set information flag 68. This step checks circuit 1530 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 may set or intermittent harsh upshifts may be caused by 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.

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