Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
All Models
After completing appropriate DRIVE CYCLE TEST, perform KOEO and CONTINUOUS MEMORY CODE SELF-TEST. If Code 99/624, 67/634 or 651 is present, go to step 92). If none of these codes are present but Code 29/452 is present, go to CIRCUIT TEST DP for all other models. If Code 11/111 is present, fault cannot be duplicated at this time.
92) Code 99/624, 67/634 Or 651 Code 99/624 and 651 indicate 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 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/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.
93) Check Circuit Harness & Connectors Shake and bend EEC-IV wiring harness. Lightly tap on components to simulate road shock. Perform KOEO Continuous Monitor Mode. See CIRCUIT TEST KOEO CONTINUOUS MEMORY CODES . 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.
| Code | Fault |
|---|---|
| 49/617 | 1 - 2 Shift Incorrect |
| 56/637 | Excessive TOT Circuit Voltage |
| 59/618 | 2 - 3 Shift Incorrect |
| 66/638 | Inadequate TOT Circuit Voltage |
| 69/628 | 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 |
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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