Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1987 Ford Ranger 2WD L4-140 2.3L DSL TurboFACTORY OEM SERVICE PROCEDURE
Cruise Control Module: Testing and Inspection
Use only a multi-meter of 5000 ohm/volt rating or higher when performing amplifier test.
``On'' Circuit Test
1. Turn ignition ``On.''
2. Connect a voltmeter between light blue wire w/black hash and ground on models exc. 1983-87 Ranger, 1984-87 Bronco II and 1986-87 Aerostar or white wire w/purple stripe and ground on 1983-87 Ranger, 1984-87 Bronco II and 1986-87 Aerostar.
3. Battery voltage should be indicated when ``On'' switch on steering column is depressed and held. If battery voltage is not indicated, check horn relay and perform control switch test.
4. Release ``On'' button. Voltmeter should indicate 7.8 volts indicating ``On'' circuit is engaged. If voltage does not remain, check amplifier ground, fuses or circuit breakers or replace amplifier with known good amplifier and repeat test.
5. Replace as necessary.
``Off'' Circuit Test
1. Turn ignition ``On.''
2. Connect a voltmeter between light blue wire w/black hash and ground.
3. Depress ``Off'' button. Voltage should drop to zero indicating ``On'' circuit is de-energized.
4. If voltage does not drop to zero, perform ``Control Switch Test.''
``Set-Accelerate'' Circuit Test
1. Turn ignition ``On.''
2. Connect a voltmeter between light blue wire w/black hash and ground.
3. Depress ``On'' switch, then hold ``Set-Accel'' button on steering wheel. Voltmeter should indicate 4.5 volts. Rotate steering wheel back and forth and check for voltmeter fluctuations. If reading varies more than .5 volts, perform ``Control Switch Test.''
``Coast'' Circuit Test
1. Turn ignition ``On.''
2. Connect a voltmeter between light blue wire w/black hash and ground.
3. Depress ``On'' switch, then depress and hold ``Coast'' button on steering wheel. Voltmeter should indicate 1.5 volts. Rotate steering wheel back and forth and check for voltage fluctuations. If reading varies more than .5 volts, perform ``Control Switch Test.''
``Resume'' Circuit Test
1. Turn ignition ``On.''
2. Connect a voltmeter between light blue wire w/black hash and ground.
3. Depress and hold ``Resume'' button. Voltmeter should indicate 6.5 volts. If all circuits are functioning properly, perform ``Servo Assembly Test'' using a known good amplifier. Do not replace amplifier before performing servo test.
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.
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