Electrical Power Steering (EPS) Signal Circuit Troubleshooting

Electrical Power Steering (EPS) Signal Circuit Troubleshooting

1. Start the engine, and let it idle.

2. Align the steering wheel straight ahead.

3. Check the EPS SIGNAL in the DATA LIST with the HDS.

Does it indicate LOW?
YES - Go to step 4.

NO - Go to step 6.


4. Turn the steering wheel quickly to the full lock position.

5. Check the EPS SIGNAL in the DATA LIST with the HDS.

Does it change to HIGH?
YES - The EPS signal circuit is OK.

NO - Go to step 12.


6. Turn the ignition switch to LOCK (0).

7. Jump the SCS line with the HDS.

8. Disconnect ECM connector E (31P).

9. Disconnect the EPS control unit 14P connector.

10. Connect ECM connector terminal E16 to body ground with a jumper wire.






11. Check for continuity between EPS control unit 14P connector terminal No. 13 and body ground.

Is there continuity?
YES - Substitute a known-good EPS control unit, Service and Repair then recheck.

NO - Repair open in the wire between the ECM (E16) and the EPS control unit.






12. Turn the ignition switch to LOCK (0).

13. Disconnect the EPS control unit 14P connector.

14. Turn the ignition switch to ON (II).

15. Measure the voltage between ECM connector terminals A9 and E16.

Is there battery voltage?
YES - Substitute a known-good EPS control unit, Service and Repair then recheck.

NO - Go to step 16.






16. Turn the ignition switch to LOCK (0).

17. Jump the SCS line with the HDS.

18. Disconnect ECM connector E (31P).

19. Check for continuity between ECM connector terminal E16 and body ground.

Is there continuity?
YES - Repair short in the wire between the ECM (E16) and the EPS control unit.

NO - Update the ECM if it does not have the latest software, ECM Update or substitute a known-good ECM, Initial Inspection and Diagnostic Overview then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM. Service and Repair