Test No. 26: Auto Lock/Unlock System Does Not Operate
- Check door lock motor on the inoperative power door lock. See DOOR LOCK MOTOR under COMPONENT TESTS. If door lock motor is okay, go to next step. If door lock motor is defective, replace door lock assembly and recheck operation of auto lock/unlock system.
- Check wiring harness and electrical connectors between door lock motor and body Electronic Control Unit (ECU). See WIRING DIAGRAMS in POWER DOOR LOCKS - TRUCKS (EXCEPT SEQUOIA) article. Body ECU may also be referred to as integration relay. 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 operation of auto lock/unlock system.
- 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 operation of auto lock/unlock system.
- Replace body ECU with a known-good body ECU and recheck operation of auto lock/unlock system. If auto lock/unlock system operates properly, original body ECU was defective. If auto lock/unlock system still does not operate properly, check wiring harness and electrical connectors for body ECU and power door lock motor for an intermittent problem. See WIRING DIAGRAMS in POWER DOOR LOCKS - TRUCKS (EXCEPT SEQUOIA) article. Repair wiring harness or electrical connector as necessary.