Fuse #10 Keeps Blowing -- No Apparent Reason

[sharkd]

A month ago, after trailering the car back from a race at VIR (about a 45 minute drive), fuse #10 blew out while I was pulling the car off the trailer. This cause the tach, fuel, water temp and econo gauges to go dead, the A/C and blower switches to die and the check light system to stop functioning.

I've checked the dash wiring, the SI board, etc without any apparent luck. The fuse sometimes blows when starting, but generally it's when accelerating -- it seems independent of whether the blower is on or the A/C switch (which operates the Aux fan, only) is pressed. The OBC has power, but it won't show fuel status or mileage.

Prior to that first blown fuse, I had not made any wiring changes, nor had I had any electrical issues. The day before the fuse blew, I had a rather severe off-course excursion (though there was about an hour and a half of track driving between when I went off in T17 and when the fuse blew.)

Any suggestions on where to look first? (Likely culprits?)

I have two days at Summit Point coming this weekend... if I can't find the fault (likely a rubbing wire), does it seem like a bad idea to throw a 7.5amp aircraft circuit breaker into the dash and run wires to the fuse location?

[bimmer2288]

I'm not an expert, but you could have snagged a ground wire while you were off roading. Look in the manual for some wiring diagrams and you may be able to find the locations of your grounds. If one is loose, I would tend to think that it would be your culprit.

[M-technik-3]

Fuse 10 cotrols the reverse light circuit correct? Check that. It goes thru the boot in the shifter cause it to pop due to shorting to ground.

[sharkd]

Originally Posted by M-technik-3

Fuse 10 cotrols the reverse light circuit correct? Check that. It goes thru the boot in the shifter cause it to pop due to shorting to ground.

Greg, go ahead and pat yourself on the back... I had "eliminated" the reverse light switch by making sure that the reverse lights were lit when in gear.

On your suggestion, figuring it was easier to check the reverse wiring than pulling the dash and center console to check my relocated check panel (my other suspect), I got the passenger side in the air. Lo, and behold, the giubo had eaten into the green and white wire that carries power to the switch and was starting on the blue and white signal wire. (I wonder if the reverse lights were momentarily lighting up under acceleration.)

Thanks!

Originally Posted by bimmer2288

I'm not an expert, but you could have snagged a ground wire while you were off roading. Look in the manual for some wiring diagrams and you may be able to find the locations of your grounds. If one is loose, I would tend to think that it would be your culprit.

A loose/bad ground, particularly the main instrument ground, would explain some of the symptoms, but it wouldn't explain a chronic blown fuse, or the working speedometer.

[M-technik-3]

Not a problem, I had the same issue on my Eta. But mine snapped as soon as I put a fuze in the holder and applied power.

[d_wierda]

take ur leather shift boot off, you'll see a wire running into the rubber shift boot, this wire will be frayed or cut. i guarantee you this is the problem, wrap the wire of with some electrical tape, heat shrink watever, problem solved

[u3b3rg33k]

I restrained the reverse light wires with zip ties on mine when I did the slushbox to manual conversion. I didn't want to have to take off my exhaust to fix wiring. I was unaware that they could cause that much trouble though.

[Stück]

This is a very very common issue on e30's. The stock clips that hold the wire loom away from the driveshaft are often broken either from age, or someone performing service in the area who doesn't think they need to be replaced.

Zipties perform the function pretty reliably otherwise.

[Soviet1942]

I'm having the same issue I will tomorrow in the morning to see if that is the issue.

I would also like to add that when I saw the blown fuse I immediately replaced it not knowing what amp was needed (there was a 15 in there so I replaced with another 15), after noticing I replaced it with a 7.5 and it blew as soon as the car got power. Would there be another issue if this had occurred with the 15 was in place of the 7.5 for a period of time?

[Soviet1942]

bump