Keeps blowing stereo, dome lights, power locks and keyless entry 10A fuse.

GeeTeeFiveOh

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About a week ago I went on a good rip down the highway and had several electrical issues that may seem un-related.

Problem 1: My check engine light came on while driving and the car started running really rich doing steady speed, my wideband was reading out 11:1 AFR. I'm sure it started running in open loop and ignoring the o2 sensors. My wiring was questionable on one o2 sensor as I extended it with some wire and a shoddy soldering job. So I did not panic, figured I needed to redo the o2 sensor wiring properly.

Problem 2: Decided it was time to cut my joy ride short and head home, on the way back my speedometer dropped down to zero and did not come back on for the rest of the trip. My speedo was questionable also as it likes to get stuck at 90km/h when I pass that speed and slow back down. The needle would stay at 90 even though I'm clearly going faster or slower. It always freed itself and started working again. Not this time it was fully dead. Once again not too worried, figured the speedometer in the cluster was toasted. Thought about changing it out before this because of the getting stuck at 90 issue.

Problem 3: When I got home I realized my key fob was no longer working to lock / unlock the doors or trunk. tried the power lock switch inside the car and it too was dead. Checked some other things, stereo dead, dome lights dead and the horn also wouldn't work (I custom made a brush switch to get power to the horn button on my momo wheel so its possible thats the problem for the horn.)

Solution: The wiring did look like shit on the o2 sensor and the connections pulled apart with barely any force. I took my time and re-wired the o2 sensor nicely. Poking around underneath the car I found the speedometer pickup had one broken wire going to the connector on the tranny. I took my time and did a nice job soldering up a connection.

Started looking for blown fuses under the dash and found a burned out 10A fuse. Replaced the fuse and it blew immediately on insertion. Took the battery off, installed another fuse, put battery back on and I heard the fuse blow from outside the car.

Did some research and found the keyless entry module is on that circuit and can cause problems. Fully disconnected the keyless module, replaced the fuse and voila it did not blow this time. I went for a drive and there is no check engine light the car was running beautifully and the speedometer functioned better than ever, still gets snagged at 90 sometimes tho.

I want my keyless entry, power locks and dome lights back. Don't want to buy another module only to find its not the problem and will keep blowing the fuse. What would cause the keyless entry module to blow or could it be something else on the circuit that's currently not operational ( power locks, dome lights or horn)

Sorry for the huge post just wanted to get it all out in sufficient detail. Thanks big time to anyone who can help me with this.
 

Tony

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just a guess here but the drivers side trunk area has the computer for the whole keyless lock,alarm system and maybe if u havent already check wiring around that and the connections. speedo and all that i have no clue...:(
 

ttocs

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try disconnecting the keyless module and replace the fuse. unfortunatly short of starting to carefully inspect wires electrical gremlins can be a royal PIA>
 
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GeeTeeFiveOh

GeeTeeFiveOh

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Hmm interesting. Maybe Scott will chime in he is pretty good with electrical. I can't say I've had this problem because I have an aftermarket alarm in mine.

After a quick Google search I came up with this:http://forums.corral.net/forums/94-95-tech/970812-8-fuse-blowing-94-gt-vert.html
Don't know if that the fuse you are referring to.

Thanks for the replies guys, I've checked the link out as well as a couple others that have came up through Google. They all pointed to the keyless entry module being fried along with a smell of burn electrical coming from the module itself.

To get driving I've removed the whole module and have been running without it ever since. Fuse was replaced and has not blown since the module is unhooked.

I found one thread on AllFordMustang, I STILL CANT COPY PASTE ANYTHING IN THIS FORUM WITH MY GOOGLE CHROME BROWSER

The guy trouble shooted his keyless entry module down to a circuit within called "MOV1" its a varistor of some sort and I've taken mine apart to look at it. My multimeter reads 9 ohms on that varistor so I don't think its bad. From what I understand that is the component on the board that fails when a current spike occurs.

I will trouble shoot the board further once I get a hold of my friends FLUKE multimeter, I don't trust my multimeters at all really. One reads 9 ohms fairly consistently and the other two read open circuit. I did not smell anything burnt at all.

Ill check my wires by the driver door again as I know they were messed with, first my car had an alarm system that was removed before I bought it. This caused all kinds of gremlins such as car continuing to run after key removed etc etc etc. I've gone over those wires and remade the connections since.

Thanks for the suggestions keep them coming if you have them !
 
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GeeTeeFiveOh

GeeTeeFiveOh

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try disconnecting the keyless module and replace the fuse. unfortunatly short of starting to carefully inspect wires electrical gremlins can be a royal PIA>

The fuse stays in shape with the module out, my power locks and dome lights however don't work with the module off. Tell me about it, gremlins have made me want to burn this sucker to the ground more than once lol.
 

ttocs

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if it quit blowing now with the module unhooked I would hope to say we found our problem. Plug it back in and see at first if it just blows anything. If not then try to lock/unlock/keyless to see if any of those blow the fuse.....
 
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GeeTeeFiveOh

GeeTeeFiveOh

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if it quit blowing now with the module unhooked I would hope to say we found our problem. Plug it back in and see at first if it just blows anything. If not then try to lock/unlock/keyless to see if any of those blow the fuse.....

Unless I replace the module or do some other repair, re-attaching it will certainly blow the fuse. Nothing has changed since I removed the module. I was not convinced the module is fried either since I smelled no electrical and the MOV1 circuit looked ok.

I don't wanna throw parts at it yet. I'm going to go over some more body wiring harnesses. Found nothing wrong yet.
 

ttocs

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the fact it doesn't look or smell bad has nothing to do with if it will function or not. I was just trying to isolate if there is a certain function of that box that blows the fuse or just being plugged in at all - IE - the lock/unlock wire on one side might be shorting out and causing it to pop when you push one button or the other.


if it straight out pops when you plug it in then you know where your problem is no matter how it looks or smells.
 
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GeeTeeFiveOh

GeeTeeFiveOh

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the fact it doesn't look or smell bad has nothing to do with if it will function or not. I was just trying to isolate if there is a certain function of that box that blows the fuse or just being plugged in at all - IE - the lock/unlock wire on one side might be shorting out and causing it to pop when you push one button or the other.


if it straight out pops when you plug it in then you know where your problem is no matter how it looks or smells.

Ok thanks for the good advice. I priced one out at a local wrecker. Only 20$ but no guarantee. Guess I'll stop being cheap
 

ttocs

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Like I said it could possibly be a short in the lock circuit that is causing it as well. You might just disconnect the switches in the doors, then try a new fuse and plugging it in. The hrn's on the back of the switches are just held in by 2 screws, the panel pops right out and again it might help to isolate the problem. Otherwise $20 and it will still pop fuses, then you know what test to do though...
 
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GeeTeeFiveOh

GeeTeeFiveOh

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That's more good advice. Either way when I fix this problem I will certainly inform everyone of the outcome. I may give that idea a try with my old module since I cant find anything wrong with the circuitry.
 

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