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 Jeep WagoneerFACTORY OEM SERVICE PROCEDURE
Ground Circuits
- Using an ohmmeter, check for continuity to ground on ECU ground terminals. Refer to the ECU GROUND CIRCUITS table. Also, see Figure and Figure . Resistance should be zero ohms. If not, repair open ground circuit.
- Using a DVOM, touch negative lead of voltmeter to a good ground. See Figure or Figure . Touch positive lead of voltmeter to each ground terminal. See ECU GROUND CIRCUITS table. With vehicle running, voltmeter reading should be less than .1 volt. If voltmeter reading is greater than .1 volt, check for open, corrosion or loose connection on ground lead.
ECU GROUND CIRCUITS
| Application | ECU Terminals |
|---|---|
| 2.5L | No. 1, 2 & 10 |
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.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
Comes to youSame-day available12-month warranty
Get a Free QuoteNo obligation. See pricing before you book.