DTC Troubleshooting: P1623 (00)
DTC P1623:
 ECM Power Source Circuit Unexpected Voltage
NOTE: Before you troubleshoot, record all freeze data and review the general troubleshooting information.
  1. Turn the ignition switch ON (II).
  1. Clear the DTC with the HDS.
  1. Turn the ignition switch OFF, and wait 2 minutes.
  1. Turn the ignition switch ON (II).
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P1536 or P1623 indicated?
YES -
Go to Step 6 .
NO -
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the under-hood fuse/relay box and the ECM.■
  1. Turn the ignition switch OFF.
Is PGM-FI main relay 1 OK?
YES -
Go to Step 9 .
NO -
  1. Disconnect ECM connector No. 2 (58P).
  1. Check for continuity between ECM connector No. 2 terminal No. 19 and body ground.
Is there continuity?
YES -
Repair short in the wire between the under-hood fuse/relay box and ECM connector No. 2 terminal No. 19, then go to Step 12 .
NO -
Go to Step 11 .
  1. Measure voltage between ECM connector No. 2 terminal No. 1 and body ground.
Is there battery voltage?
YES -
Repair short to power in the wire between the under-hood fuse/relay box and ECM connector No. 2 terminals No. 1, No. 3 or No. 5, then go to Step 12 .
NO -
Go to Step 16 .
  1. Reconnect all connectors.
  1. Turn the ignition switch ON (II).
  1. Reset the ECM with the HDS.
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P1623 indicated?
YES -
Check for poor connections or loose terminals at the under-hood fuse/relay box and the ECM, then go to Step 1 .
NO -
Troubleshooting is complete. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.■
  1. Reconnect all connectors.
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P1623 indicated?
YES -
Check for poor connections or loose terminals at the under-hood fuse/relay box and the ECM. If the ECM was updated, substitute a known-good ECM, then recheck. If the ECM was substituted, go to Step 1 .
NO -
If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.■