Diagnostic Aids
Perform this test only when directed by QUICK TEST. This test is intended to diagnose following items:
- Wiring Harness Circuits CLS, SS1, SS3, EPC, MCCC, TOT, MLP And VPWR
- ECA
| Code | Fault |
|---|---|
| 617 | 1-2 Shift Incorrect |
| 637 | Excessive TOT Circuit Voltage |
| 618 | 2-3 Shift Incorrect |
| 638 | Inadequate TOT Circuit Voltage |
| 628 | 2-3 Shift Incorrect |
| 619 | 3-4 Shift Incorrect |
| 645 | Inadequate 1st Gear Command Response |
| 646 | Inadequate 2nd Gear Command Response |
| 647 | Inadequate 3rd Gear Command Response |
| 648 | Inadequate 4th Gear Command Response |
| 656 | Continuous Slippage Detected |
- 90) Vehicle Preparation Ensure all components are connected. Ensure transmission fluid level is correct. Warm engine to normal operating temperature. Perform KOEO SELF-TEST and CONTINUOUS MEMORY CODE SELF-TEST. If Code 617, 637, 618, 638, 619, 628, 645, 646, 647, 648 or 656 is present, go to step 93). If none of these codes are present, go to step 91).
- 91) Drive Cycle Test With transmission gear selector in Overdrive position, moderately accelerate vehicle to 50 MPH for at least 15 seconds. Transmission should be in 4th gear. While holding speed steady, lightly apply and release brake for about 5 seconds. Stop and park vehicle for a minimum of 20 seconds with transmission gear selector in Drive position. Repeat procedure 5 times. After completing appropriate drive cycle test, perform KOEO and CONTINUOUS MEMORY CODE SELF-TESTS. If Code 624, 634 or 651 is present, go to step 92). If none of these codes are present, but Code 452 is present, go to CIRCUIT TEST DP . If Code 11 or 111 is present, fault cannot be duplicated at this time.
- 92) Code 624, 634 Or 651
Codes 624 and 651 indicate Electronic Pressure Control (EPC) failure. Code 634 indicates Manual Lever Position (MLP) sensor is out of calibration. Following are possible causes of faults:
- Faulty EPC Solenoid
- Faulty MLP Sensor
- Circuit Open Or Grounded
- Damaged ECA Connector Pins
Turn ignition off. Disconnect 60-pin ECA connector. Inspect terminals and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect ECA to breakout box. To test EPC solenoid, connect DVOM to EPC test pin and EPC VPWR test pin at breakout box. To test MLP sensor, connect DVOM to MLP test pin and test pin No. 46 at breakout box. For EPC solenoid and MLP sensor, turn ignition on. Voltage for EPC should be less than 10 volts. Voltage for MLP should be less than 5 volts. Shake and bend EPC and MLP wiring harness. Lightly tap on components to simulate road shock. Voltage should remain stable. If voltage changes or exceeds specification, fault in circuit is indicated. Isolate and repair fault as necessary. Clear continuous memory codes, and repeat QUICK TEST . If no faults are found, problem cannot be located at this time.
- 93) Check Circuit Harness & Connectors Shake and bend EEC-IV wiring harness. Lightly tap on components to simulate road shock. Perform KOEO WIGGLE TEST. See CONTINUOUS MONITOR MODE (WIGGLE TEST) in article. If fault is indicated, isolate and repair as necessary. See CIRCUIT TEST KOEO CONTINUOUS MEMORY CODES table. Clear continuous memory codes, and repeat QUICK TEST . If no faults are found, problem cannot be located at this time.