Cruise Control - Inoperative During Road Test
NUMBER: 15-25-85APPLICABILITY 1985 STATION WAGON AND 4-DOOR SEDAN VEHICLES DATE: 09-11-85
WITH SPECIFIC CRUISE CONTROL
SUBJECT: CRUISE CONTROL QUICK CHECK PROCEDURE
THIS SERVICE BULLETIN IS FOR YOUR INFORMATION ONLY.
1985 Station Wagon and 4-Door Sedan vehicles with Specific Cruise control can be checked for proper operation with the cruise module tester box and harness. Every new cruise installation should be checked for proper operation at the completion of the installation. The tester can check every function of the cruise control system. A test light is required for diagnostic work.
NOTE: Complaints of cruise systems operating normally according to the tester and then not operating during a road test can usually be traced to a poor connection at the module. The connection at the module should be checked after module reinstallment to ensure that the module multipin connector stays firmly seated on the module.
FIGURE 1 - Cruise Module Tester Box - All Years:
Figure 1 illustrates the difference between the 1984 and 1985 test harness. Make sure you are using the right one.
The following is a quick test procedure which has been condensed from the 1985 Specific Cruise Control Parts/Service Manual. It was designed to allow an installing technician to quickly check for proper cruise operation in place of a test drive. It is meant for use only after initial installation of a cruise control system. The procedure should not be used as a substitute for the diagnostic procedures found in the Parts/Service Manual when troubleshooting previously installed cruise control systems.
QUICK TEST PROCEDURE
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 underdash panels. Loosen attaching screws for electronic module and remove module. Refasten screw containing ground wire firmly to ensure a good ground. Disconnect cruise wiring harness from electronic module. Attach module tester to cruise harness and electronic module.
3. Control switch operation may be checked with key and cruise in Off position. Operating the control switch in its respective positions, Resume - Set - Off, should cause the corresponding light on the module tester to illuminate with switch function.
4. Turn key to ON position (Do not start vehicle). TACH and IGNITION lights should be on.
For automatic transmission vehicles, NEUTRAL light will be on in neutral or park. Module tester will not operate for automatics in neutral or park. Place car in Drive when using module tester and NEUTRAL light should go out. Manual transmission vehicles should be in neutral.
5. SPEED light may be on or off depending on the position of the speed sensor's reed switch contacts. Roll car several feet and Speed light should blink on and off.
6. Turn cruise on by twisting control switch forward. RESUME will flash momentarily with switch function. SAFETY, TACH, IGNITION, VAC, VENT should now be on.
7. 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(es). This is important. Vac and Vent lights will go out when pedal is depressed also.
8. 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.
9. Depress brake pedal in automatic transmission equipped vehicles and accelerator pedal should return. Depress clutch pedal in manual transmission equipped vehicles and accelerator pedal should return.
10. Now twist switch forward to Resume function and hold while accelerator pedal goes to floor. Release switch when accelerator pedal has hit floor or stopped moving toward floor. TACH, IGNITION, and VAC should now be on. Vent may flicker.
11. Now press and hold Set/Decel button. Accelerator pedal should return to idle position.
12. Release button when pedal returns to idle position and pedal may go toward floor again depending on vacuum supply remaining.
13. Disconnect tester. Start engine to build vacuum, shut engine off, reconnect tester and repeat test as necessary to confirm proper operation.
If the vehicle has passed all these tests, it will operate on the road unless a connection fails to conduct properly. Inspect all connections when a failure is encountered.
Please consult the Parts/Service Manual (MSA 461B) should you encounter a non-operating cruise control unit.
The following lists some common reasons for inoperation which should be checked first.
1. Brake lamp fuse or cruise fuse being blown (#3 & #20 in the fuse box, respectively).
2. Brake light bulb(s) burned out.
3. M/T vehicles in which the clutch pedal does not fully return to its rest position with enough force to completely close the clutch switch. (See Service Bulletin #03-36-84, dated 12-7-84).
4. Poor connections. This is the most common reason for erratic operation. Carefully check that all wires are seated in their plastic connectors, especially the white w/red tracer wire in position #12 on the multipin connector at the module.
5. Make sure the module connector is fully seated on the module in its "as installed" condition due to the sharp bend the wire harness makes at this location.
A "sectional" approach to diagnosis may make diagnosis easier. After visibly confirming proper wire and vacuum line connections, narrow the possible failure candidates down to the module.
1. Check the fuses and control switch.
2. Check the clutch, safety, and stop lamp switch.
3. Check speed sensor.
4. Use button on the tester box to completely isolate and check the servo, valve body, vacuum lines and reservoir.
Complete information is contained in the 1985 Parts/Service Manual.