Cruise Control - Diagnosis & Service Procedure
NUMBER: 15-19-85
APPLICABILITY 1985 STATION WAGON AND SEDAN DATE: 02-14-85
WITH SPECIFIC CRUISE CONTROL
SUBJECT: CRUISE CONTROL INTRODUCTION AND DIAGNOSIS PROCEDURE
The 1985 Station Wagon and Sedan Specific Cruise Control System can be diagnosed with the present SOA Module Tester box used on 1984 and prior models. A different wiring harness is necessary, however, to adapt the Module Tester box to the 1985 Station Wagon and Sedan. A different test procedure must also be followed for the 1985 Station Wagon and Sedan. The Module Tester box, harness, and procedure for 1984 models must be followed for 1985 BRAT and Hatchback.
Module Tester box and Harness part numbers and descriptions are listed below. It is suggested that both tester harnesses have their own Module Tester box to avoid frequent plugging and unplugging which may promote contact block wear or loose connections. Please be aware that 1985 Station Wagon and Sedan harnesses have a 16 pin module connector while the 1985 Hatchback and BRAT and 1984 and prior harness has a 15 pin module connector.
1984 and Prior Module Tester, complete w/harness -SOA460442
1984 and Prior Module Tester harness only -SOA460452
1985 Station Wagon and Sedan Module Tester, complete w/harness -SOA386C402
1985 Station Wagon and Sedan Module Tester harness only -SOA386C400
Cruise Module Tester box only - All Years/Models -SOA386C401
All parts are available through the normal Parts channels.
The following procedure can be used to diagnose the 1985 Station Wagon and Sedan Specific Cruise Control System using the Module Tester and Harness. An alternate method of troubleshooting when the Module Tester is unavailable, is also provided.
SUBARU MODULE TESTER INSTRUCTIONS
CAUTION: DO NOT START ENGINE WITH THE TESTER INSTALLED.
1) Start car and run engine for at least one minute to build up vacuum. Shut engine off.
2) Remove driver side under-dash panels. Loosen attaching screws for Electronic Module and remove Module. Re-fasten screw containing ground wire firmly to ensure ground. Disconnect cruise wiring harness from Electronic Module. Attach Module Tester to cruise harness and Electronic Module.
FIGURE 1 - Fuse Box:
3) Control switch operation may be checked with key and Cruise in the Off position. Operating control switch in its respective positions, Resume - Set - Off, should cause the corresponding light on the Module tester to illuminate with switch function. If not, check 15 amp fuse in position #3 of the fuse box, which is the stop light fuse. See Figure 1.
4) Turn key to ON position. TACH, and IGNITION lights should be on. If not, check 15 amp cruise fuse in position #20 in fuse box. See Figure 1. Also check power lead to cruise (green wire/red tracer with blue connectors) to confirm connection. For automatic transmission equipped vehicles, NEUTRAL light will be on in neutral and park. Module tester will not operate for automatic's in neutral or park. Place car in Drive when using Module Tester and NEUTRAL light should go out. Manual transmission vehicles place in neutral. SPEED light may be on or off depending on the speed sensor's reed switch contacts. Roll car several feet and SPEED light should blink on and off. If not, check cruise harness connection to speed sensor and wiring continuity to the speedometer head. If it checks good, the sensor in the speedometer is defective and should be replaced according to applicable Service Manual instructions.
5) Turn cruise on by twisting control switch forward - RESUME will flash momentarily with switch function. SAFETY, TACH, IGNITION VAC, VENT should now be on. If Ignition light is on and Vac or Vent light is off, this indicates either a bad valve body, wiring short to ground, or poor connection between valve and module. Use buttons on Module Tester to test the valves according to Step 13.
6) Depress brake pedal - BRAKE/CLUTCH light will come on. SAFETY will go out. BRAKE/CLUTCH light should come on before SAFETY goes out. If not, adjust switch(s) to achieve correct operation. Vac and Vent light will go out with brake pedal application also.
7) Momentarily press Set button and release - Safety and Vent should go out. Accelerator pedal should go toward floor. Vent may flicker. Lights On - TACH, IGNITION, VAC. If lights respond as indicated but the pedal does not move, the Module is good and the remainder of the system is at fault. Perform Reservoir and Servo test as described in Step 14. If the lights and the pedal do not respond as indicated, the Module may be faulty. Perform further tests as described in Steps 8, 12, 13 and 14 before condemning Module.
8) Depress brake pedal in automatic transmission vehicles and accelerator pedal should return. Depress brake or clutch pedal in manual transmission vehicles and accelerator pedal should return. When depressing brake pedal, lights will function as in Step 6. Vent and Safety lights should come on when depressing clutch pedal. Lights on now-SAFETY, TACH, IGNITION, VAC., VENT. If not, re-check switch adjustments and switch continuity.
9) Now twist switch forward to Resume function and hold while accelerator pedal goes toward floor. Release switch when accelerator pedal has hit floor or stopped moving toward floor. Resume should flash with switch action. Safety and Vent lights will go out. Vent may flicker. Lights on now-TACH, IGNITION, VAC.
10) Now press and hold Set/Decel button. Set and Vent should come on with button function. Lights on-SET, TACH, IGNITION, VAC, VENT. Accelerator pedal should return to idle position.
11) Release button when accelerator pedal returns to idle position and pedal may go toward floor again, depending on vacuum supply remaining. Safety and Vent lights should go out. Vent may flicker. Lights on-TACH., IGNITION, VAC.
12) Disconnect tester - Start engine to build vacuum, shut engine off, re-connect Tester and repeat test as necessary to confirm proper operation. Let engine run long enough to build adequate vacuum supply.
13) In the event that the unit does not pass any of the above tests, the three buttons on the Module Tester may be used to isolate valve problems.
A) Repeat Step 12 to build vacuum supply if necessary.
B) Depress Safety, Vent, and Vacuum buttons in that order and hold down. Accelerator pedal should go to floor.
C) Release the Vacuum button and accelerator pedal should remain on floor.
D) Release the Vent button and the accelerator pedal should return.
E) Repeat the test but release the Safety button to return the accelerator pedal.
F) Depressing any one of the buttons should produce a corresponding click from the valves under the hood if the valve is functioning and the unit is wired correctly. If the valve body will not pass above tests, check wiring continuity and if okay, replace valve body.
14) The Reservoir and Servo and apply hose may also be tested with a hand vacuum pump to isolate component part problems. Connect pump to Servo apply hose and pump vacuum. Servo should pull accelerator pedal to floor and keep it there until vacuum is released. Vacuum reservoir can also be checked by pumping down and seeing if vacuum holds.
If the SOA Module Tester is not available, it is still possible to test to see if all electrical connections are made properly. A standard 12 volt test light may be used by probing with the test light at the circuit board located between the white wire harness connector and the black plastic module housing. A voltmeter is required for the speed sensor test.
Starting from the ground wire which is solid black in the number one position in the connector, work to the yellow wire at the other end. Do these tests with the key on and the Cruise turned on.
#1 GROUND WIRE (Black wire) - Connect clip of test light to 12 volts and probe at #1 position. Light should be bright. If light is not bright, repair ground (See Wiring Diagram).
#2 ON/RESUME/ACCEL/SET (Dark blue wire) - Connect clip of test light to ground and probe at #2 position. Light should come on with switch function. If not, check wire continuity.
#3 DECEL/SET (White wire) - Connect clip of test light to ground and probe at #3 position. Light should come on with switch function. If not, check wire continuity.
#4 BRAKE/LAMP (Green w/white wire) - Connect clip of test light to ground and probe at #4 position. Light should come on when brake pedal is depressed. If not, check switch and wire continuity.
#5 BRAKE/FUSE (Green w/yellow wire) - Connect clip of test light to ground and probe at #5 position. Light should be on all the time if the fuse is good.
#6 CLUTCH (Green w/yellow wire) - Connect clip of test light to 12 volt source and probe at #6 position. Light should be on and go out when clutch pedal is depressed. If not, check switch and wire continuity.
#7 AUTOMATIC TRANSMISSIONS ONLY: NEUTRAL (Black/yellow wire) - Connect clip of test light to 12 volt source and probe at #7 position. Light should come on only when car is in neutral or park. If not, test wiring continuity.
#8 OVERSPEED TACH (Yellow w/white wire) - Connect clip of test light to ground and probe at #8 position with engine running. Light should flash on/off continuously. If not, test wire continuity to negative side of coil in engine compartment.
#9 SPEED SENSOR (Yellow w/blue wire) - Using a voltmeter, place the positive lead at position #9 and the negative lead to position #1 which is ground. Roll the vehicle several feet. The voltmeter should read 0 to 5-6 volts alternately.
CAUTION: Use of ohmeters or test lights for testing the speed sensor on the 1985 Station Wagon and Sedan vehicles is not recommended due to the sensitivity of this reed switch.
#10 OFF (Yellow wire) - Connect clip of test light to ground and probe at #10 position. Twist control switch to Off and light should flash on with switch function. If not, check wire continuity. Remember to turn Cruise back on to continue testing.
#11 IGNITION (Green w/red wire) - Connect clip of test light to ground
and probe at #11 position. Light should be on. If not, check wire continuity.
#12 VALVE POWER (White w/red wire) - Connect clip of test light to ground and probe at #12 position. Light should be on. If not, check wire continuity to valve body.
#13 SAFETY (Blue w/red wire) - Connect clip of test light to ground and probe at #13 position. Light should glow dim. If not, check wire continuity to valve body.
#14 VAC (Brown wire) - Connect clip of test light to ground and probe at #14 position. Light should glow dim. If not, check wire continuity to valve body.
#15 VENT (Yellow wire) - Connect clip of test light to ground and probe at #15 position. Light should glow dim. If not, check wire continuity to valve body.
Test drive vehicle when possible to confirm proper operation.