All Models

Turn ignition off. Check vacuum hoses for cracks or leaks. Replace hoses as necessary. If no vacuum leaks are found, check control cable freeplay. Cablke freeplay should be less than .39" (10 mm).
If cable freeplay is not as specified, adjust control cable freeplay. If cable freeplay is as specified, disconnect actuator connector. Check operation of atuator. If actuator is not operating properly, replace actuator.
If actuator is operating properly, disconnect stop light switch connector. Check for continuity between terminal No. 4 of connector and body ground.
If continuity is present, check for short between terminal No. 1 (terminal No. 3 on Corolla and Supra) of stop light switch. If no continuity is present, reconnect actuator connector.
Check for continuity between terminal No. 4 of connector and body ground. If no continuity is present, check for open between terminal No. 1 (terminal No. 3 on Corolla and Supra) of stop light switch.
If continuity is present, check operation of stop light switch. If switch is not operating properly, replace stop light switch. If switch is operating properly, reconnect stop light switch connector.
Disconnect computer connector. Check for continuity between terminal Nos. 2 and 14 with stop light switch released. If no continuity is present, check for open between terminal Nos. 2 and 14 of computer.
If continuity is present, check for continuity between terminal Nos. 2 and 14 with stop light switch depressed. If continuity is present, check for short circuit in wire between terminal Nos. 2 and 14 of computer.
If no continuity is present, check for continuity between terminal Nos. 4 and 14. If no continuity is present, check for open between terminal Nos. 4 and 14 of computer. If continuity is present, replace cruise control computer.