Test No. 21: Power Door Lock System Does Not Operate When Using Manual Switch

Check body Electronic Control Unit (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 power door lock system operation.
Replace body ECU with a known-good body ECU and recheck power door lock system operation. If power door lock system operates properly, original body ECU was defective. If power door lock system still does not operate properly, check wiring harness and electrical connectors for body ECU and power door lock system for an intermittent problem. See WIRING DIAGRAMS in POWER DOOR LOCKS - TRUCKS (EXCEPT SEQUOIA) article. Body ECU may also be referred to as integration relay. Repair wiring harness or electrical connector as necessary.