Test No. 4: Automatic Light Control System Does Not Operate
NOTE:
Automatic light control system turns on or off the headlights, park lights, taillights, side marker lights and instrument panel lights according to darkness of surrounding lighting. Headlight control switch must be position No. 3 (AUTO position) for automatic light control system to operate.
- Check wiring harness and electrical connectors between automatic light control sensor and body Electronic Control Unit (ECU). See WIRING DIAGRAMS in DAYTIME RUNNING LIGHTS article. Body ECU may also be referred to as integration relay. Automatic light control sensor is located at driver's side corner of instrument panel, near end of air vent. See Fig 1. 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 connector are okay, go to next step. If wiring harness or electrical are defective, repair as necessary and recheck automatic light control system operation.
- 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 automatic light control system operation.
- Replace body ECU with a known-good body ECU and recheck automatic light control system operation. If automatic light control system operates properly, original body ECU was defective. If automatic light control system still does not operate properly, check wiring harness and electrical connectors for automatic light control sensor and body ECU for an intermittent problem. See WIRING DIAGRAMS in DAYTIME RUNNING LIGHTS article. Repair wiring harness or electrical connector as necessary.