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.
1990 Ford Bronco II RWD, Standard, M5OD-R1FACTORY OEM SERVICE PROCEDURE
ISC Motor
- Turn key off and wait 10 seconds. Disconnect ISC motor connector. Using DVOM, touch positive lead on ISC connector VPWR terminal and negative lead on ISC terminal. See ISC MOTOR RESISTANCE . If resistance is not within specification, replace ISC motor. If resistance is correct, proceed to step 2.
- Measure resistance between either ISC connector terminal and ISC housing. Resistance should be more than 10 k/ohms. If resistance is not more than 10 k/ohms, replace ISC motor. If resistance is more than 10 k/ohms, go to step 3.
- Turn ignition on. Using a voltmeter, measure voltage between ISC motor harness connector terminals. If voltage is less than 2.0 volts, repair open circuit and repeat test. If voltage is greater than 5.5 volts, turn ignition off. With ISC connector disengaged, connect Breakout Box (014-00322) and leave processor disconnected.
- Measure resistance between breakout box test pin No. 21 and ISC terminal on ISC connector. If resistance is greater than 5 ohms, repair open circuit and repeat test. If resistance is less than 5 ohms, measure resistance between breakout box test pin No. 21 and following test pins: No. 40, No. 46 and No. 60. If resistance is less than 10 k/ohms, repair short circuit and repeat test.
ISC MOTOR RESISTANCE
| Application | Specification |
|---|---|
| "F" Series with 5.0L | 17-21 ohms |
| All Other Models | 9.5-11.5 ohms |
Factory Service Tools
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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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