Cruise Control: Testing and Inspection
Fault tracing (checking of the cruise controlFault Tracing Of The Cruise Control:
The speedometer must be working for the cruise control to work.
The control unit should only be replaced if a check of the system shows no other fault.
If the control unit is replaced without correcting faults in the system, there is a risk of the new control unit being destroyed as well.
Check that fuse 12 is sound.
Check that the brake lights are working and that the brake light switch is correctly adjusted. The brake lights must come on before the brakes engage when the pedal has been pressed down 8-14 mm. Adjust if necessary.
The control unit ground connection is through the bulbs of the brake lights in addition to terminal B. If both brake lights are defective the control unit will not work.
Remove driver's side knee bolster.
Fault Tracing Of The Cruise Control:
Fold down sound proofing.
Check vacuum valve function.
Fault Tracing Of The Cruise Control:
At brake and clutch pedal.
The valves must be closed and must not leak when the pedals are up. When pushed down the vacuum valves should open. The clearance to the shoulder of the piston must be 0.5-1.0 mm
Check clearance by connecting a hose to valve and sucking. Adjust as required.
Check all hose connections and hoses connected to vacuum valves, vacuum servo and vacuum pump. Make sure there are no leaks.
Check vacuum valves electrical operation.
Fault Tracing Of The Cruise Control:
Connect an ohmmeter between the vacuum valve terminals. The resistance must be low (closed circuit) when the pedal is released and infinite (open circuit) when the pedal is depressed.
Check vacuum servo for leaks.
Fault Tracing Of The Cruise Control:
Connect a tube to the vacuum servo and apply suction. The throttle pedal must move downwards. If the vacuum servo leaks or remains in its original position, replace it.
Check vacuum pump.
Three extra wires are needed for this check.
Fault Tracing Of The Cruise Control:
Disconnect the connector at the vacuum pump. Connect a wire between a 12-volt supply and terminal 3 of the vacuum pump.
Fault Tracing Of The Cruise Control:
Connect two wires between ground and terminals 1 and 2 of the vacuum pump. The vacuum pump should start and the vacuum servo should pull the throttle strut all the way down.
Check vacuum servo and the system for leaks.
Fault Tracing Of The Cruise Control:
Disconnect ground connection from terminal 2.
The vacuum pump must stop but the vacuum servo must remain at the bottom position. If the vacuum servo moves back, either there is leakage in the system or the vacuum pump is faulty.
Disconnect ground connection from terminal 1.
The vacuum servo must return to its initial position. If it does not do so, the vacuum pump is faulty.
Restore original connections after the test.
Check wiring
Fault Tracing Of The Cruise Control:
Switch off the ignition. Disconnect the control unit connector.
Test the connection in the connect as stated under the test procedures below.
See also the wiring diagram.
Ignition off. Cruise control switch ON.
Connect test lamp between ground and terminals 1-10 in the connector. Test lamp should not light up at any of the terminals.
If test lamp lights up at any of the terminals, this indicates incorrect connections or a short circuit.
Ignition on. Cruise control switch ON.
Connect test lamp between ground and terminal 1 in the connector. The test lamp should light up.
If test lamp does not light up, this may be because:
- fuse 12 has blown.
- a circuit is broken.
- a switch is faulty. See Check cruise control switch.
Ignition on. Cruise control switch ON.
Connect test lamp between terminals 1 and 8 of the connector. The test lamp should light up.
If test lamp does not light up, this indicates that a ground circuit is broken.
Ignition on. Cruise control switch ON.
Connect test lamp between terminals 1 and 3 of the connector.
Test lamp should light up when the pedals are up.
If test lamp does not light up the fault may be:
- vacuum valve improperly adjusted.
- open circuit in wires from terminal 3 to ground. See wiring diagram.
- wire not connected to negative side of brake light switch.
Test lamp should go out when the pedals are pressed.
If test lamp does not go out, the fault may be:
- wires incorrectly connected at brake light switch.
- short circuit in wiring.
Ignition on. Cruise control switch ON.
Connect test lamp between ground and terminal 2 of the connector.
Press SET SPEED button. Test lamp should light up.
If test lamp does not light up, the fault may be:
- in the switch, see Check cruise control switch.
- an open circuit in wiring.
Ignition on. Cruise control switch ON.
Connect test lamp between ground and terminal 6 of the connector.
Move switch to RESUME. Test lamp should light up.
If test lamp does not light up, the fault may be:
- in the switch, see Check cruise control switch.
- an open circuit in wiring
Ignition on Cruise control switch ON.
In the connector:
Connect extra wire from pin 1 (+) to pin 10.
Connect extra wire from pin 8 (-) to pin 7.
A click should be heard from engine vacuum pump.
If no click is heard or the pump does not start:
- open circuit in wiring.
Connect extra wire from pin 8 (-) to pin 4. Vacuum pump should start and vacuum servo should move throttle pedal fully down.
Remove wire from pin 4. Vacuum pump should stop.
Release throttle pedal by disconnecting wire from pin 7.
Check cruise control switch.
Fault Tracing Of The Cruise Control:
Separate cruise control switch connector.
Connect extra wire from a 12-volt supply to terminal 1.
Connect test lamp between ground and the three other connections in sequence from 2 to 4.
Test lamp should light up as shown in table below. If a fault is found, replace the cruise control switch.
Fault Tracing Of The Cruise Control:
Fault Tracing Of The Cruise Control:
