Hey my 96 Cherokee keeps blowing its fuse F20, which concerns the auto shutdown relay in the car. I need to figure out how to stop it from blowing this fuse, because obviously it doesn't let the car start when this is happening. I've looked for exposed wires and haven't found anything - not to say I haven't missed something. I have a digital multimeter, but I was confused on how to go about using it. I was wondering if anyone had some tips for me to find the reason why my fuse keeps blowing, or if anyone has had the same problem.

 

Is there a particular condition that is causing it? I had this problem in my 99 Cherokee. It started after I replaced the alternator. It kept randomly blowing the ASD fuse. I finally figured out that it was when the engine revved over a certain rpm, the fuse would blow. I swapped the alternator with a different one and no more blown fuse.

 

Well, the first time I had the issue was when I rolled to a stop on a slight decline. The fuse popped and the car shut off. The next time was after a drive I parked, and then twenty minutes later I went to start the car again and the car started and then the fuse popped and it shut off again. It has not started since, and has gone through two other fuses, so I need to find out why the fuse is blowing.

 

I don't have an answer for you, but I have the same problem happening, but only after it comes up to full operating temperature. I don't have the time to be trying to chase down shorts, so I have a pro working on it. If I get any good information, I'll pass it on here.

 

Inspect the wiring harness along the fuel injectors, especially where it crosses over to the firewall for chaffing and shorting. Bad motor mounts cause excessive flexing of this harness, and can cause the wires to fray and break inside the wiring loom.

 

Well here's what came up. Guy was running diagnostics on the computer when the engine shut down. Apparently the Downstream O2 sensor once it reached a certain temperature would develop an excessive current draw which would then blow the fuse. Never got a CEL or anything like that. So hopefully that's that. Still gonna carry some extra fuses just in case.

 

Note from DJ to alanarbor

Just for clarity for further reader what is the year of your Jeep and the number of the fuse that was blowing?

 

Sorry, it's a 1996 xj 4.0, and it's fuse #20

 

Well paid good money for bad info. Replaced the O2 sensor, and the fuse is still blowing. I'm kind of wondering how the hell they got the diagnosis though, since I'm getting no communication with my scan tool at home, (powers up but vehicle doesn't respond) and I checked it on my wife's vehicle in case the tool itself was bad, but it connected just fine. At least the jeep is in my driveway now, and I can carpool to work.

Any new ideas?

 

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Dupe post deleted.

 

My 2012 Grand Cher keeps blowing Fuse M21 (ASD Relay fuse).

My MIL came on and threw code P0430 Catalytic System Efficiency Below Threshold Bank 2 a few months ago. I did a bunch of trouble shooting, cleaned the MAF sensor, ran some cat cleaner through and it seemed to fix the problem. Fast forward a few months my wife was driving and the car stalled completely. We thought it was due to the Fuel Pump Relay recall we never had addressed. Had the Fuel pump recall performed and the car still didn't start.

Did a bunch more trouble shooting, checked the ASD relay with a voltmeter for resistance in the 50-200 ohm range as well as checked the relay with power to the control to do a click test. All checked out. Checked that the ASD was getting good voltage and it read 12.2v coming in. Checked for continuity on the ground to PCM Connector C3 and located the ground pin. All checked out. Finally thought to check the fuse it was blown.

Replaced the fuse, started right up no issues. Drove around yesterday and today. On our way to run some errands this morning the MIL came on for the P0430 code again. got to where we were going, parked the car around 9:45. Got back in to go home around 1230. About 10 mins later the car stalled. Checked the fuse and sure enough M21 popped.

Do you think P0430 could actually have something to do with it? I'm wondering if your mechanic researched it and found Code P0430 as a related fix and just assumed that might be your issue without the truck actually throwing the code versus my situation where the fuse blew after the code was thrown what seems to be twice now.