Electrical Power Steering (EPS) Signal Circuit Troubleshooting

1. Turn the ignition switch ON (II).




2. Measure voltage between ECM connector terminals A26 and B20.

Is there battery voltage?

YES - Go to step 6.

NO - Go to step 3.

3. Start the engine.
4. Turn the steering wheel to the full lock position.
5. Measure voltage between ECM connector terminals A26 and B20.

Is there battery voltage briefly?

YES - The EPS signal is OK.

NO - Go to step 10.

6. Turn the ignition switch OFF.
7. Disconnect the EPS control unit 14P connector.
8. Turn the ignition switch ON (II).




9. Measure voltage between EPS control unit terminal No. 13 and body ground.

Is there battery voltage?

YES - Substitute a known-good EPS control unit and recheck.

NO - Repair open in the wire between the ECM (A26) and the EPS control unit.

10. Turn the ignition switch OFF.
11. Disconnect the EPS control unit 14P connector.
12. Turn the ignition switch ON (II).




13. Measure voltage between EPS control unit terminal No.13 and body ground.

Is there battery voltage?

YES - Substitute a known-good EPS control unit and recheck.

NO - Go to step 14.

14. Turn the ignition switch OFF.
15. Disconnect ECM connector A (32P).




16. Check for continuity between body ground and ECM connector terminal A26.

Is there continuity?

YES - Repair short in the wire between the ECM (A26) and the EPS control unit.

NO - Substitute a known-good ECM and recheck. If the voltage is now normal, replace the original ECM.