Fail-Safe System Check

Automatic Speed Control Device (ASCD) control unit monitors system for malfunctions. If a malfunction exists, fail-safe mode is entered. If any of the following conditions are detected, CRUISE indicator light will flash in 0.4-second intervals, and fail-safe mode will deactivate ASCD operation.

Stuck ASCD steering wheel switch (RESUME/ACCEL, CANCEL, SET/COAST).
Open or shorted vacuum motor ground/power circuit.
Open or shorted air valve ground/power circuit.
Open or shorted release valve ground/power circuit.
Faulty Vehicle Speed Sensor (VSS).
Faulty ASCD control unit internal circuit.
Faulty ASCD brake switch or brakelight switch.

NOTE: Listed malfunctions will cancel vehicle set speed stored, except for a faulty cancel switch, ASCD brake switch or brakelight switch. Vehicle set speed stored is also cancelled any time ASCD MAIN switch is turned off.

If CRUISE indicator light flashes during ASCD operation, stop vehicle and turn ASCD MAIN switch off, then on. If CRUISE indicator light does not flash, go to next step. If CRUISE indicator light flashes, perform TEST 5: ASCD STEERING WHEEL SWITCH CHECK under SYSTEM TESTS.
Turn ASCD MAIN switch off. Drive vehicle and turn ASCD MAIN switch back on. Push SET/COAST switch and note CRUISE indicator light. If CRUISE indicator light flashes, go to next step. If CRUISE indicator light does not flash, go to step 4.
Perform TEST 6: VEHICLE SPEED SENSOR (VSS) CHECK under SYSTEM TESTS. If system tests okay during vehicle speed sensor check, perform TEST 7: ASCD PUMP CIRCUIT CHECK under SYSTEM TESTS. If system tests okay during ASCD pump circuit check, replace ASCD control unit.
Slowly depress brake pedal for at least 5 seconds. Observe CRUISE indicator light. If CRUISE indicator light flashes, perform TEST 4: ASCD BRAKE/BRAKELIGHT SWITCH CHECK under SYSTEM TESTS. If CRUISE indicator light does not flash, system is okay.