Test 1 (Stoplight Switch Circuit)

With brake pedal released, contacts between terminals No. 1 and 2 of stoplight switch connector are open, and contacts between terminals No. 3 and 4 are closed. When brake pedal is pressed, cruise control ECU detects, through terminal STP-, that contacts between terminals No. 1 and 2 have closed. It then stops applying power to the magnetic clutch through terminal "L". Also, contacts between terminals No. 3 and 4 open, interrupting power to the magnetic clutch, and disengaging cruise control. As a fail-safe function, if the STOP fuse opens, the system disengages cruise control.

1. If stoplights do not operate, repair stoplight circuit. If stoplights operate, check stoplight switch input signal circuit. See INPUT SIGNAL CIRCUITS . If input signal circuit is okay, perform next procedure listed in DIAGNOSIS BY SYMPTOM  table.
2. If input signal circuit is faulty, remove cruise control ECU, but leave electrical connectors attached. Turn ignition on. Measure voltage between ground and terminals No. 1 and 16 of cruise control ECU connector. See Figure. With brake pedal pressed, battery voltage should be present at both terminals. With brake pedal released, battery voltage should be present at terminal No. 1, and less than one volt should be present at terminal No. 16.