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Home >> Subaru >> 1987 >> XT DL >> Repair and Diagnosis >> Accessories & Equipment >> Cruise Control Systems >> Trouble Shooting >> System Will Not Operate

System Will Not Operate

  1. Check fuses. If fuse is blown, check cause and replace fuse. If fuse is good, check battery voltage at control unit with main switch in "ON" position. If no voltage is present, replace main switch.
  2. If voltage is present, check for properly grounded control unit. If control unit is not properly grounded, ground control unit and test control unit operation.
  3. If control unit is grounded, check if set signal is transmitted from sub-switch to control unit. If signal is not transmitted, replace control switch. If signal is transmitted, ensure vehicle speed pulse from speedometer is transmitted to control unit.
  4. If no speed pulse is transmitted to control unit, check speedometer operation. If speedometer does not operate properly, replace speed sensor located inside speedometer.
  5. If speedometer operates properly, check for faulty contact of pulse signal cable connecting speedometer to cruise control unit. If speed pulse is transmitted to control unit, check clutch switch (M/T) operation or check if 2-pole connector for clutch (A/T) is shorted or grounded.
  6. If clutch switch does not operate properly, replace switch. If clutch 2-pole connector is not shorted, short circuit and ground 2-pole connector for clutch switch.
  7. If switch and connector are good, depress brake pedal. Check if brake lights come on. If brake lights do not come on, check and replace bulb(s) as necessary. If bulbs are good, replace brake switch.
  8. If stop lights do come on, release brake pedal. Check for battery voltage at harness connector terminal of cruise control unit. If no voltage is present, replace brake switch.
  9. If voltage is present, replace control unit with a known good unit and recheck operation. If cruise control operates properly, replace control unit. If cruise control does not operate properly, install old control unit. Replace actuator with a known good actuator.
  10. Check actuator operation. If actuator operates properly, replace actuator. If actuator does not operate properly, install old actuator. Replace valve assembly with a known good valve.
  11. Check valve operation. If valve operates properly, replace valve. If valve does not operate properly, reinstall old valve. Replace pump assembly with a known good pump. Check pump operation. If pump operates properly, replace pump. If pump does not operate properly, check wiring, connections and hoses.
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