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Test No. 5: Headlight Does Not Operate

  1. Check headlight bulb. If headlight bulb is okay, go to next step. If headlight bulb is defective, replace headlight bulb and recheck headlight operation. If headlight still does not operate, go to next step.
  2. Check appropriate fuse for inoperative headlight. See WIRING DIAGRAMS in DAYTIME RUNNING LIGHTS article. HEAD LH and HEAD RH fuses are located in fuse/relay box at driver's side front corner of engine compartment. See Figure. H-LP LHLO and H-LP RHLO fuses are located in fuse/relay box at front of engine compartment, just behind the grille. See Figure. If all fuses are okay, go to next step. If any fuse is defective, replace fuse and repair wiring harness or electrical connector on wiring circuit as necessary. See WIRING DIAGRAMS in DAYTIME RUNNING LIGHTS article.
  3. Check headlight relay. See HEADLIGHT RELAY  under COMPONENT TESTS. If headlight relay is okay, go to next step. If headlight relay is defective, replace headlight relay and recheck headlight operation.
  4. Check wiring harness and electrical connectors between battery and headlight relay, and between headlight relay, daytime running light relay and Body Electronic Control Unit (ECU). See WIRING DIAGRAMS in DAYTIME RUNNING LIGHTS article. Body ECU may also be referred to as integration relay. Daytime running light relay is located in fuse/relay box at front of engine compartment, just behind the grille. See Figure. Body ECU is located at driver's side of instrument panel on the fuse/relay box. See Figure. Electrical connector I13 (7-pin or 25-pin) and electrical connector I16 (18-pin) are located at body ECU and a 12-pin electrical connector is located at rear of body ECU. See Figure. It may be necessary to check daytime running light relay, daytime running light relay (main) and headlight dimmer relay. For relay testing, see DAYTIME RUNNING LIGHT RELAY , DAYTIME RUNNING LIGHT RELAY (MAIN)  and HEADLIGHT DIMMER RELAY  under COMPONENT TESTS. If wiring harness and electrical connector are okay, go to next step. If wiring harness or electrical are defective, repair as necessary and recheck headlight operation.
  5. Check headlight control switch. See HEADLIGHT CONTROL SWITCH  under COMPONENT TESTS. If headlight control switch is okay, go to next step. If headlight control switch is defective, replace headlight control switch and recheck headlight operation. See HEADLIGHT CONTROL SWITCH  under REMOVAL & INSTALLATION.
  6. Check wiring harness and electrical connectors between headlight control switch and body ECU. See WIRING DIAGRAMS in DAYTIME RUNNING LIGHTS article. Body ECU may also be referred to as integration relay. Electrical connector I13 (7-pin or 25-pin) and electrical connector I16 (18-pin) are located at body ECU and a 12-pin electrical connector is located at rear of body ECU. See Figure. If wiring harness and electrical connector are okay, go to next step. If wiring harness or electrical are defective, repair as necessary and recheck headlight operation.
  7. Check body ECU for proper voltage and input signals. See BODY ELECTRONIC CONTROL UNIT  under PIN VOLTAGE TESTS. If proper voltage and input signals exist, go to next step. If proper voltage and input signals do not exist, repair as necessary and recheck headlight operation.
  8. Replace body ECU with a known-good body ECU and recheck headlight operation. If headlight operates properly, original body ECU was defective. If headlight still does not operate properly, check wiring harness and electrical connectors for body ECU for an intermittent problem. See WIRING DIAGRAMS in DAYTIME RUNNING LIGHTS article. Repair wiring harness or electrical connector as necessary.
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