System Diagnosis - Cadillac Electronic Cruise Control
Fig. 4 Electronic cruise control wiring diagram. 1982 with V6-252 except Eldorado & Seville with digital instrument cluster:
Fig. 5 Electronic cruise control wiring diagram. 1982---84 All with diesel engine except Eldorado & Seville with digital instrument cluster:
Fig. 6 Electronic cruise control wiring diagram. 1982---84 Eldorado & Seville with diesel engine & digital instrument cluster:
Fig. 7 Electronic cruise control wiring diagram. 1983---84 DeVille and Brougham diesel:
1982---84 MODELS
For diagnosis on vehicles equipped with Digital Electronic Fuel Injection (D.E.F.I.), refer to COMPUTERIZED ENGINE CONTROLS.
ELECTRIC BRAKE RELEASE SWITCH
On Vehicle Check
1. Place instrument panel switch to ``On-Auto'' position.
2. Connect a suitable test lamp to ground.
3. Probe pink-black wire at the cruise control brake switch connector, Figs. 4 through 7. Test lamp should light indicating voltage.
4. Check switch adjustment with probe still connected at the pink-black wire. Depressing the brake pedal 1-8 inch---1-2 inch should turn test lamp off.
5. If lamp did not light in step 3, probe wire in adjacent connector cavity. If voltage is indicated, adjust switch or replace as necessary. If test lamp did not light, wiring to switch is faulty, refer to wiring diagrams in this section.
Off Vehicle Check
1. Use a suitable ohmmeter or powered test light connected across switch contacts to check for switch continuity.
2. Depress switch plunger. Ohmmeter should indicate continuity or test light should light.
3. With switch plunger extended, ohmmeter should indicate infinity or test light should be off.
INSTRUMENT PANEL SWITCH
On Vehicle Check
1. Turn ignition ``On'' and connect a suitable test lamp to ground.
2. Disconnect the three wire connector from the turn signal lever engagement switch harness to the cruise harness connector.
3. Probe the three terminals of the cruise harness connector, first with the instrument panel switch in ``Off'' position, then in the ``On-Auto'' position. In ``Off'' position, there should be no power to any of the terminals. In the ``On-Auto'' position, pink-black wire, test lamp should indicate current, and the yellow and red wire of the terminal should not indicate current. Also, in the ``On-Auto'' position the amber indicator should light on the instrument panel.
ENGAGEMENT SWITCH & HARNESS
The engagement switch can only be checked after disconnecting it from the harness. Using a suitable ohmmeter, the following tests can be performed:
1. With the engagement switch in the released position, continuity should not exist in any of the three terminals.
2. With the engagement switch in the slide depressed position, continuity should exist between terminals 1 and 2.
3. With the engagement switch in the push button depressed position continuity should exist between terminals 2 and 3.
4. If incorrect indications occur, replace engagement switch and harness.
5. With any one lead connected to the steering column mounting bracket, check each terminal. All three terminals should show no continuity. If any terminal indicates continuity, a short exists and the lever and harness should be replaced.
VACUUM CONTROL & SERVO UNIT SOLENOID VALVES
Resistance Test (Engine Off)
1. Disconnect electrical connector at the solenoid being tested.
2. Connect an ohmmeter to the solenoid valve terminals.
3. Measure resistance. It should be between 35 and 48 ohms on servo unit valve and between 23.5 and 27.5 ohms on vacuum control valve.
4. If reading obtained is outside of limits replace applicable valve.
Functional Test (Engine Off)
1. Disconnect electrical connector at valve being tested.
2. Connect a jumper wire from the positive terminal of the battery to one terminal of the valve being tested.
3. Connect another jumper wire to ground.
4. Brush the other end of the grounded jumper wire across the remaining terminal of the valve. You should hear the vacuum control valve or servo unit solenoid valve open and close as you make and break contact with the terminal. Both valves will click twice indicating that each respective valve is functioning properly.
Functional Test (Engine Operational)
1. Prior to starting the engine, disconnect the bead chain, cable or rod actuator at the servo unit.
2. Disconnect electrical connectors at the vacuum control and servo unit valves.
3. Start engine and let idle. Install jumper wires from battery positive terminal to one terminal on both vacuum control valve and servo unit solenoid valve. Ground second terminal on each valve. Servo diaphragm should fully retract, indicating both solenoid valves are functional.
4. Remove battery jumper from servo solenoid. The diaphragm should return to full extension proving that no vacuum is reaching it. If it does not fully return, the servo unit solenoid valve is leaking and should be replaced.
5. Reinstall battery wire to servo solenoid and remove battery jumper from the vacuum control valve. Diaphragm should return to full extension. If it does not, the vacuum control valve is leaking and should be replaced.
CONTROLLER CURRENT LEAKAGE TEST AT SERVO UNIT SOLENOID VALVE CONNECTOR (ENGINE OPERATIONAL)
1. Disconnect electrical connector at servo solenoid valve.
2. With engine operating at idle, check D.C. voltage between connector terminals. Reading obtained should be less than 1.0 volt D.C.
3. Momentarily increase idle speed for several seconds. Voltmeter should indicate less than 1.0 volt D.C.
4. If any indications are above 1.0 volt D.C., the controller should be replaced.
INSTRUMENT PANEL SWITCH (AMBER ``ON'' LAMP INOPERATIVE OR MALFUNCTIONING)--ENGINE OFF
1. Turn ignition switch ``On''.
2. Place instrument panel switch in ``On-Auto'' position.
3. If amber ``On'' lamp is not illuminated, check for burned-out lamp, open ground wire, open connector, inoperative switch, blown fuse or printed circuit.
4. Place instrument panel switch in ``Off'' position.
5. If amber ``On'' lamp is illuminated, check for shorted leads or inoperative switch.
INSTRUMENT PANEL SWITCH (GREEN ``CRUISE'' LAMP CIRCUIT)
1. If road test shows system controls speed and green indicator light is inoperative, check for burned out lamp, an open in wiring between switch connector and controller connector (pink wire), or an inoperative controller.
2. Place instrument panel switch in ``On-Auto'' position (ignition on), ground cavity ``B'' in controller connector; green lamp should light. If green lamp is on but not during road test, replace controller.
3. If green indicator remains ``On'' when system is not controlling speed, check for shorts in harness between switch and controller connector (pink wire). If not damaged, replace controller or ECM.
CONTROLLER
There should be no attempt made to repair the Electronic Cruise Controller.
On all models, ensure the controller 8 and 3-way connector contacts are clean and properly seated. If all other components have been checked and found to be operating properly, replace controller.
Fig. 4 Electronic cruise control wiring diagram. 1982 with V6-252 except Eldorado & Seville with digital instrument cluster:
Fig. 5 Electronic cruise control wiring diagram. 1982---84 All with diesel engine except Eldorado & Seville with digital instrument cluster:
Fig. 6 Electronic cruise control wiring diagram. 1982---84 Eldorado & Seville with diesel engine & digital instrument cluster:
Fig. 7 Electronic cruise control wiring diagram. 1983---84 DeVille and Brougham diesel:
SPEED SENSOR
This test requires a high quality voltmeter (20,000 ohms per volt or greater).
1. Turn ignition ``On'' and place switch to ``On-Auto'' position.
2. Remove speedometer cluster partially for access to the speed sensor 3-way connector located on the electronic controller. Connect voltmeter between ground and black wire terminal, Figs. 4 through 7. Voltage should read between 9 and 11 volts. Voltage is less than battery voltage because of the internal circuitry of the electronic controller. If voltage is outside of limits, replace controller.
3. Connect voltmeter between ground and red wire terminal, Figs. 4 through 7. Voltage should be 1 to 2 volts less than value in the black wire terminal. This is the voltage drop through the light emitting diode. If voltage is outside of limits, replace sensor.
4. Connect voltmeter between ground and green wire terminal. Roll vehicle forward while checking voltage. Voltage should fluctuate at least 5 volts from low points to peaks (output of photo transistor) and each peak should be within 1 volt of reading at black wire terminal (step 2 above).
VACUUM SYSTEM (ENGINE OPERATIONAL)
1. Prior to starting the engine, disconnect the bead chain, cable or actuator rod at the servo unit.
2. Disconnect electrical connectors at the vacuum control and servo unit solenoid valves.
3. Actuate vacuum control and servo unit solenoid valve with jumper wires by connecting jumper wires from the battery positive terminal to one terminal on each valve and grounding the remaining terminal on each valve with another set of jumper wires.
4. Start engine and let idle.
5. With brake pedal in free position, diaphragm should pull into full stroke. Depress the brake pedal about 11-2 inches. The diaphragm should relax to its free position proving that the vacuum release valve is working and its hose is unobstructed.
6. If system will not hold vacuum, remove brake release vent valve hose at servo unit and plug servo unit hole (manifold vacuum should be open).
7. If servo unit draws down then problem condition exists in brake release vacuum vent system.
8. If servo unit will not draw down, inspect diaphragm and connectors at valves for leaks.