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.
  1. Disconnect the under-hood fuse/relay box connector D (20P).
  1. Check PGM-FI main relay 1.
Is PGM-FI main relay 1 OK?
YES -
Go to Step 9 .
NO -
Replace the under-hood fuse/relay box, then go to Step 13 .
  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 .