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Procedure K, Vacuum Circuit

  1. Vacuum Hose:  Inspect vacuum actuator vacuum hose for cracks or other damage. Replace damaged vacuum hose, and recheck cruise control system. If hose is okay, go to next step.
  2. Vacuum Switch:  Disconnect vacuum switch, which is an integral part of vacuum actuator assembly. Check continuity between vacuum switch body and ground. If continuity exists, go to next step. If no continuity exists, repair open circuit in wire harness between switch body and ground. Also check for faulty ground.
  3. Check vacuum switch operation. See VACUUM SWITCH TEST  under TESTING. If switch is faulty, replace switch. If switch is okay, go to next step.
  4. Vacuum Pump:  Disconnect vacuum pump. Check continuity between wiring harness side of vacuum pump terminal No. 2 and ground. See Figure. If continuity exists, go to next step. If no continuity exists, repair open circuit in wire harness between vacuum pump terminal No. 2 and ground. Also check for faulty ground.
  5. Check vacuum pump operation. See VACUUM PUMP TEST  under TESTING. If pump is faulty, replace vacuum pump. If pump is okay, go to next step.
  6. Cruise Control ECU:  Reconnect vacuum switch and pump. Disconnect ECU. Check continuity between wiring harness side of ECU terminal No. 11 and ground. See Figure. If continuity exists, go to next step. If no continuity exists, repair open circuit in wire harness between ECU terminal No. 11 and vacuum switch terminal No. 1 (Red/Blue wire).
  7. Start engine and allow it to idle. Check continuity between wiring harness side of ECU terminal No. 11 and ground. If no continuity exists, go to next step. If continuity exists, repair short circuit in wire harness between ECU terminal No. 11 and vacuum switch terminal No. 1 (Red/Blue wire).
  8. Stop engine. Check continuity between vacuum pump terminal No. 1 and ground. See Figure. If continuity exists, go to next step. If no continuity exists, repair open circuit in wire harness between ECU terminal No. 2 and vacuum pump terminal No. 1.
  9. With vacuum pump disconnected, check continuity between vacuum pump terminal No. 1 and ground. If no continuity exists, replace faulty ECU and recheck cruise control system. If continuity exists, repair short circuit in wire harness between ECU terminal No. 2 and vacuum pump terminal No. 1.
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