Diagnostic Aids

Perform this test only when directed by QUICK TEST. This test is intended to diagnose:

• Wiring harness circuits (CCS, SS1, SS2, SS3, EPC, TCC, TOT, and MLP).
• Powertrain Control Module (PCM).

90) Drive Cycle Test (AODE & E4OD)  Ensure all components are connected. Ensure transmission fluid is correct level. Warm engine to normal operating temperature. Perform KOEO and CONTINUOUS MEMORY CODE SELF-TEST. Clear all codes.

With transmission gear selector in Drive, press Transmission Control Switch (TCS). Transmission Control Indicator Light (TCIL) should come on. Moderately accelerate vehicle to 40 MPH for at least 15 seconds (30 seconds above 4000 feet elevation). Transmission should be in 3rd gear. While holding speed steady, press TCS. TCIL should go off. Accelerate from 40 MPH to 50 MPH. Transmission should shift from 3rd gear to 4th gear. Hold speed steady for 15 seconds. While holding speed steady, lightly apply and release brakes to turn brakelights on. Maintain 50 MPH for about 5 seconds. Stop and park vehicle for a minimum of 20 seconds with transmission gear selector in Drive. Repeat procedure 5 times.

After completing DRIVE CYCLE TEST, perform KOEO and CONTINUOUS MEMORY CODE SELF-TEST. If Code 11/111 is present, fault cannot be duplicated at this time. If Code 99/624, 67/634 or 651 is present, go to step 91). If Code 29/452 is present, go to CIRCUIT TEST DP. If any other code(s) is present, go to step 92).

Fig 1: MLP Sensor Circuit & Wiring Connector Terminal ID (AODE)

Fig 2: MLP Sensor Circuit & Wiring Connector Terminal ID (E4OD)

91) Code 99/624, 67/634 Or 651  Code 99/624 or 651 indicates Electronic Pressure Control (EPC) failure. Code 67/634 indicates that Manual Lever Position (MLP) sensor is out of calibration. Possible causes for these faults are:

• Faulty EPC solenoid
• Faulty MLP sensor.
• Circuit open or grounded.
• Damaged PCM connector pins.

Turn ignition off. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM 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/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. If fault is indicated, isolate and repair as necessary. Clear continuous memory codes, and repeat QUICK TEST. If no faults are found, problem cannot be located at this time.

92) Check Circuit Harness & Connectors  Enter CONTINUOUS MONITOR MODE (WIGGLE TEST) under QUICK TEST. Shake and bend EEC wiring harness while observing analog VOM or scan tester. Lightly tap on components to simulate road shock. If VOM indicator has erratic movement or scan tester beep, fault is indicated. If fault is indicated, isolate and repair as necessary. Clear continuous memory codes, and repeat QUICK TEST. If fault is still present, problem is in transmission. If no faults are found, problem cannot be located at this time. See SUMMARY in this article.