DTC Troubleshooting

DTC P1658: Electronic Throttle Control System (ETCS) Control Relay ON Malfunction

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.

1. Turn the ignition switch ON (II).
2. Do the ETCS TEST in the INSPECTION MENU with the HDS.

Is the RELAY circuit OK?

YES - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the ETCS control relay and the PCM.

NO - Go to step 3.

3. Turn the ignition switch OFF.
4. Remove the ETCS control relay (A) from the under-hood fuse/relay box.






5. Test the ETCS control relay.

Is the ETCS control relay OK?

YES - Go to step 6.

NO - Replace the ETCS control relay, then go to step 13.

6. Jump the SCS line with the HDS.
7. Disconnect PCM connector A (44P).
8. Check for continuity between PCM connector terminal A20 and body ground.






Is there continuity?

YES - Repair short in the wire between the PCM (A20) and the ETCS control relay, then go to step 13.

NO - Go to step 9.

9. Disconnect PCM connector C (44P).
10. Turn the ignition switch ON (II).
11. Measure voltage between PCM connector terminal C4 and body ground.






Is there battery voltage?

YES - Repair short to power in the wire between the PCM (C4) and the ETCS control relay, then go to step 12.

NO - Go to step 18.

12. Turn the ignition switch OFF.
13. Reconnect all connectors.
14. Turn the ignition switch ON (II).
15. Reset the PCM with the HDS.
16. Do the PCM idle learn procedure.
17. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P1658 indicated?

YES - Check for poor connections or loose terminals at the ETCS control relay and the PCM, then go to step 1.

NO - Troubleshooting is complete. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTCs troubleshooting.

18. Reconnect all connectors.
19. Update the PCM if it does not have the latest software, or substitute a known-good PCM.
20. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P1658 indicated?

YES - Check for poor connections or loose terminals at the ETCS control relay and the PCM. If the PCM was updated, substitute a known-good PCM, then recheck. If the PCM was substituted, go to step 1.

NO - If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTCs troubleshooting.