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Test No. 15: Low Beam Circuit Does Not Operate (With Daytime Running Lights)

WARNING: This page is about a different car, the 2002 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.
    CAUTION: When handling halogen headlight bulb, DO NOT scratch or drop the bulb, as bulb is pressurized and may burst. DO NOT touch glass part of headlight bulb with your hands. Hold headlight bulb only by plastic or metal case.
  1. Remove and examine headlight bulb which is not operating. If headlight bulb is defective, replace headlight bulb and recheck headlight operation. If headlight bulb is okay, check wiring harness and electrical connectors. See HEADLIGHTS in SYSTEM WIRING DIAGRAMS article. Repair wiring harness or electrical connectors as necessary. After repairs, perform confirmation test. See CONFIRMATION TEST .
  2. Depending on which headlight is inoperative, check HEAD LH LWR fuse (15-amp) for driver side low beam headlight or HEAD RH LWR fuse (15-amp) for passenger side low beam headlight. Fuses are in engine compartment junction block located in front of shock tower on left side of engine compartment. See Figure. If fuse is okay, go to next step. If fuse is defective, repair short in wiring between appropriate fuse and headlight. See HEADLIGHTS in SYSTEM WIRING DIAGRAMS article.
  3. Check headlight control relay. See HEADLIGHT CONTROL RELAY  under COMPONENT TESTS. If headlight control relay is okay, go to next step. If headlight control relay is defective, replace headlight control relay. After repairs, perform confirmation test. See CONFIRMATION TEST .
  4. Check wiring harness and electrical connectors between battery and headlight control relay. Headlight control relay is located in engine compartment junction block in front of shock tower on left side of engine compartment. See Figure. Power feed circuit (Red/Black wire) to headlight control relay is from MAIN (40-amp) fuse located in engine compartment junction block. Power feed circuit (Black wire) to MAIN fuse is from ALT (120-amp) fuse located in engine compartment junction block. Power feed circuit (Black wire) from battery to ALT fuse is through a fusible link located near battery. To test Red/Black wire between headlight control relay terminal No. 4 and driver side junction block-to-body control ECU 12-pin connector terminal No. 8, ECU must be separated from driver side junction block. See BODY CONTROL ELECTRONIC CONTROL UNIT  under REMOVAL & INSTALLATION. See Figure. See HEADLIGHTS in SYSTEM WIRING DIAGRAMS article. If wiring harnesses and electrical connectors are okay, go to next step. If wiring harnesses or electrical connectors are defective, repair as necessary. After repairs, perform confirmation test. See CONFIRMATION TEST .
  5. Check headlight dimmer switch. See HEADLIGHT DIMMER SWITCH under COMPONENT TESTS under STEERING COLUMN SWITCHES - AVALON article in ACCESSORIES & EQUIPMENT. If headlight dimmer switch is okay, go to next step. If headlight dimmer switch is defective, replace light control switch. After repairs, perform confirmation test. See CONFIRMATION TEST .
  6. Check wiring harness and electrical connectors between light control switch and body control ECU, between body control ECU and headlight control relay, and between headlight control relay, headlights and ground connections. See HEADLIGHTS in SYSTEM WIRING DIAGRAMS article. If wiring harnesses or electrical connectors are defective, repair as necessary. After repairs, perform confirmation test. See CONFIRMATION TEST .
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