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.
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HOMESERVICE MANUALSJEEP1987WAGONEER BASE, 4.0 M, AUTOMATICREPAIR AND DIAGNOSISENGINE PERFORMANCETUNE-UPIGNITION SYSTEM - SOLID STATETESTINGCONTROL UNIT POWER FEED
1987 Jeep Wagoneer Base, 4.0 M, Automatic
Control Unit Power Feed
1987 Jeep Wagoneer Base, 4.0 M, AutomaticSECTION Control Unit Power Feed
NOTE:
Always check ignition coil primary circuit first before making this check.
- Disconnect 2-wire connector at control unit. Connect voltmeter negative lead to ground and positive lead to harness connector terminal "F2". Turn ignition on. Voltage reading should be within .2 volts of battery voltage. If reading is correct, replace control unit and go to step 3).
- If reading is not correct, locate and repair cause of voltage reduction (corroded connectors, defective ignition switch, etc.). If connectors are repaired and there is spark at coil wire, start engine. If connectors are repaired but no spark at coil wire, replace control unit.
- Turn ignition switch off and connect 2-wire connector. Disconnect 4-wire connector and connect an ammeter between Black wire terminal "C1" of control unit connector and ground. Turn ignition on. Reading should be .9-1.1 amps. If reading is not as specified, replace control unit.
RENDER: 1.0x
NO RELATED
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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.