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1991 XJ with no power.

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Old 10-31-2021, 09:21 PM
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Question 1991 XJ with no power.

I had a buddy that jumped up to jump on the hood of my jeep and it grounded out the battery through the hood and now it has zero power. ive read that on jeeps its not automatically the ecu that gets fried and was wondering if anyone had any ideas to check out before jumping to replace the ECU.
On a side note this is an offroad only rig so does anyone know a way to make youre own wiring harness to the ignition/fuel pump/ motor so that it could run on its own where all i really need is lights and the motor to work.
Old 11-01-2021, 09:57 PM
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Shorting the battery to ground or across the terminals shouldn't kill the ECU. I'd check for battery cable or ground cables to the engine. Could be a melted fusible link or blown fuse too. Does it crank and not fire, or what? Spark, fuel?

Being fuel injected, you need to keep most of the wiring harness and the goal of building you own minimal harness isn't realistic.
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Old 11-02-2021, 03:57 AM
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I'd agree to check for fuses too. I had a buddy that jump started his XJ with the leads on the wrong way around, and he just blew a fuse.
Old 11-02-2021, 09:40 AM
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Originally Posted by lawsoncl
Shorting the battery to ground or across the terminals shouldn't kill the ECU. I'd check for battery cable or ground cables to the engine. Could be a melted fusible link or blown fuse too. Does it crank and not fire, or what? Spark, fuel?

Being fuel injected, you need to keep most of the wiring harness and the goal of building you own minimal harness isn't realistic.
I need to go out where its sitting ang go through everything with my power probe and i was thinking it might be the engine ground but i havent had a ton of time to dig into it. i will check it out this weekend. As far as the lack of power when the key is turned on nothing happens at all no lights or bells or anything comes on.
Old 11-02-2021, 10:22 AM
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Do the basics. Check the battery cables and connections. He probably knocked it slightly loose. You may have a good enough connection that you can measure correct voltage with a meter, but once you put any load on it, bye bye.

I think with electrical troubleshooting, the thing that trips people up the most is thinking that if they can measure voltage, the connection is good. Not so. Partial connections are responsible for a lot of problems.
Old 11-03-2021, 09:39 PM
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There are some fusible links near the starter relay that should be looked at too.
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