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Procedure H, Stoplight Switch Circuit

  1. Stoplight Fuse: Ensure ignition is off. Check stoplight fuse. Replace fuse if blown. If fuse blows, check wiring harness for a short circuit between cruise control ECU terminal No. 18 (Green/Red wire) or terminal No. 1 (Green/Red wire) of stoplight switch and fuse. If fuse is okay, go to next step.
  2. Stoplight Switch: Disconnect stoplight switch. Check continuity between wiring harness side of stoplight switch terminal No. 3 (Green/White wire) and ground. If continuity exists, go to next step. If no continuity exists, repair wiring harness open circuit between stoplight switch terminal No. 3 (Green/White wire) and ground. Also check for faulty ground.
  3. Check stoplight switch operation. See STOPLIGHT SWITCH TEST under TESTING in this article. If switch is faulty, replace switch and recheck cruise control system. If switch is okay, reconnect stoplight switch and go to next step.
  4. Cruise Control ECU: Disconnect electronic control unit. Check for battery voltage between wiring harness side of ECU terminal No. 18 (Green/Red wire) and ground with brake pedal released. If voltage is correct, go to next step. If voltage is incorrect, repair wiring harness open circuit between ECU terminal No. 18 (Green/Red wire) and stoplight fuse.
  5. Check for battery voltage between wiring harness side of ECU terminal No. 17 (Green/White wire) and ground with brake pedal depressed. If voltage is correct, replace faulty ECU and recheck cruise control system. If voltage is incorrect, repair wiring harness open circuit between ECU terminal No. 17 (Green/White wire) and stoplight switch terminal No. 3 (Green/White wire).
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