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 Mustang L4-140 2.3L SOHCFACTORY OEM SERVICE PROCEDURE
Cruise Control Module: Testing and Inspection
Use only a voltmeter of 5000 ohm/volt rating or higher when performing the following amplifier test.
``On'' Circuit Test
1. Turn ignition ``On.''
2. Connect a voltmeter between 296 and ground at the amplifier. Check battery voltage.
3. Connect a voltmeter to circuit 151 and ground at the amplifier. Voltmeter should read battery voltage when speed control switch is ``On,'' depressed and held. If there is not voltage, refer to ``Control Switch Test.''
4. Release ``On'' button. Voltmeter should read approximately 7.8 volts, indicating the ``On'' circuit is engaged. If voltmeter reads zero, check ground and amplifier. Also check the fuse and circuit breaker.
``Brake'' Circuit Test, 1984---87 All Models
1. Connect an ohmmeter between red/light green wire and ground.
2. Resistance should measure less than 5 ohms.
3. If resistance is greater than 5 ohms, check for burned out stop lamps, improper wiring or clutch malfunction.
Factory Service Tools
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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