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ABS DTC Troubleshooting: 54-04, 54-21

DTC 54-04:
 Fail-safe Relay 1 Stuck OFF (Initial)
DTC 54-21:
 Fail-safe Relay 1 Stuck OFF (Main)
  1. Turn the ignition switch to ON (II).
  1. Clear the DTC with the HDS.
  1. Turn the ignition switch to LOCK (0), then turn it to ON (II) again.
  1. Check for DTCs with the HDS.
Is DTC 54-04 or 54-21 indicated?
YES -
Go to Step 5 .
NO -
Intermittent failure, the system is OK at this time. Check for loose terminals at the ABS modulator-control unit 25P connector. Refer to intermittent failures troubleshooting.
  1. Turn the ignition switch to LOCK (0).
  1. Check the No. 37 (30 A) fuse in the under-dash fuse/relay box.
Is the fuse blown?
YES -
Go to Step 7 .
NO -
Reinstall the checked fuse, then go to Step 14 .
  1. Check for continuity between ABS modulator-control unit 25P connector terminal No. 8 and body ground.
Is there continuity?
YES -
Repair short to body ground in the wire between the No. 37 (30 A) fuse in the under-dash fuse/relay box and the ABS modulator-control unit.■
NO -
Install a new No. 37 (30 A) fuse in the under-dash fuse/relay box, then go to Step 9 .
  1. Reconnect the ABS modulator-control unit 25P connector.
  1. Turn the ignition switch to ON (II).
  1. Clear the DTC with the HDS.
  1. Turn the ignition switch to LOCK (0), then turn it to ON (II) again.
  1. Check for DTCs with the HDS.
Is DTC 54-04 or 54-21 indicated?
YES -
NO -
The system is OK at this time.■

  1. Measure the voltage between ABS modulator-control unit 25P connector terminal No. 8 and body ground.
Is there battery voltage?
YES -
Check for loose terminals in the ABS modulator-control unit 25P connector. If necessary, substitute a known-good ABS modulator-control unit, and retest.■
NO -
Repair open in the wire between the No. 37 (30 A) fuse in the under-dash fuse/relay box and the ABS modulator-control unit.■