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Test No. 10: Only One Interior Light Does Not Operate

  1. Check bulb in front interior light, vanity light (if equipped) or interior lights No. 1 or 2 which do not operate. Front interior light and interior lights No. 1 and 2 are located on the headliner. See Figure. Vanity light is located on each sun visor. See Figure. If bulb is okay and light does not operate, go to next step. If bulb is defective, replace bulb and recheck light operation.
  2. Check front interior light, interior light No. 1, interior light No. 2 or vanity light which do not operate. See FRONT INTERIOR LIGHT , INTERIOR LIGHT NO. 1 , INTERIOR LIGHT NO. 2  or VANITY LIGHT  under COMPONENT TESTS. If light is okay, go to next step. If light is defective, replace light or switch as necessary and recheck light operation.
  3. Check wiring harness and electrical connectors between battery and the inoperative light, and between the inoperative light and Body Electronic Control Unit (ECU). See WIRING DIAGRAMS in ILLUMINATION/INTERIOR LIGHTS article. Body ECU may also be referred to as integration relay. Front interior light may also be referred to as front personal light or personal light. 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. If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary and recheck light operation.
  4. 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 light operation.
  5. Replace body ECU with a known-good body ECU and recheck light operation. If light operates properly, original body ECU was defective. If light still does not operate properly, check wiring harness and electrical connectors for body ECU and inoperative light for an intermittent problem. See WIRING DIAGRAMS in ILLUMINATION/INTERIOR LIGHTS article. Repair wiring harness or electrical connector as necessary.
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