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
Power Circuits
Using a voltmeter, check for battery voltage between ECU terminal No. 1 and ground. If battery voltage is not present, check Blue fusible link. If fusible link is okay, check for an open in wire to terminal No. 1 on ECA.
ECA LOCATION
| Application | Location |
|---|---|
| Aerostar | Left Dash Panel |
| Bronco & "F" Series | Behind Left Kick Panel |
| Bronco II & Ranger | Behind Right Kick Panel |
| "E" Series | Right of Dash Panel, Under Blower Motor |
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
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.