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Home >> Isuzu >> 1990 >> Impulse Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests - EFI >> Relays & Switches >> Main Relay Test (Impulse)

Main Relay Test (Impulse)

  1. Main relay is located in fuse/relay box at left front corner of engine compartment, near strut tower.
  2. Remove main relay connector. Using ohmmeter, check for continuity between terminals No. 1 (Black/Yellow wire) and No. 3 (Black wire). Replace relay if no continuity is present. If continuity is present, proceed to step 3).
  3. Using jumper wires, ground terminal No. 3 (Black wire) and apply battery voltage to terminal No. 1 (Black/Yellow wire). Using ohmmeter, check for continuity between terminals No. 2 (Red/White wire) and No. 4 (Red/Green wire). Check voltage at terminal No. 2 (Red/White wire) of relay.
  4. If no voltage is present, check for defective ECM fuse, located in fuse/relay box at left front corner of engine compartment. If fuse is okay, check for open in wiring between ECM fuse and main relay.
  5. Check for battery voltage at terminal No. 1 (Black/Yellow wire) with ignition on. If no voltage is present, check for defective fuse No. 11 in junction block, located at left kick panel. If fuse is good, check for open in wiring between junction block and main relay.
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