Fuse 31 blowing after brake work

UK forum for general and technical discussion about the Z3 roadster
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firebladeboy
Joined: Thu 04 Jul, 2013 10:27
Posts: 3

  Z3 roadster 2.8

Fuse 31 blowing after brake work

Post by firebladeboy »

Hi Everyone,

Just had the brake pads and discs/rotors replaced on my 1999 Z3. On way home from garage noticed no clocks were working - speedo, revs, nothing. Turns out Fuse 31 had blown. Replaced it with another 5 amp fuse and it immediately blew again. Put a 10amp in there and it's holding so far but this was just a bodge. I don't want to cause more problems if there's a short somewhere by leaving the wrong fuse in place.

Does anyone have any idea what may have been damaged during brake-work that could cause this fuse to pop?

Thanks in advance,

FBB
NZ00Z3
Joined: Thu 23 Jun, 2016 01:26
Posts: 95

  Z3 roadster 3.0i

Re: Fuse 31 blowing after brake work

Post by NZ00Z3 »

Fuse 31, 5A, hot all the time. If its blowing a 5A fuse there is a problem. Fitting a larger fuse, just lets the wiring cook a bit more before it blows too. Cooked melted wiring is just a pain to fix and can be the death knell for the car. As the fuse is hot all of the time, take the fuse out.

Get yourself a set of wiring diagrams. You will need to know your build date because there are 2 different sets of drawings that cover 1999 cars.
Get them from here. http://wedophones.com/BMWManualsLead.htm

Drawing 0670.3-10 shows you the devices feed by fuse 31. Can't see any that would be knocked or damaged by a brake job. Use this drawing to start disconnecting devices and see which one is the problem.
firebladeboy
Joined: Thu 04 Jul, 2013 10:27
Posts: 3

  Z3 roadster 2.8

Re: Fuse 31 blowing after brake work

Post by firebladeboy »

Hi,

Thanks for the reply.

I checked the fuse and it's stone-cold, even after a 10 minute run. I also tried a 12v test light across the fuse terminals and it didn't light so I'm thinking the problem has gone away. Will get some more 5amp fuses and replace the 10amp and see what happens. If it has gone away I guess I'll just have to wait for recurrence.

Cheers!
firebladeboy
Joined: Thu 04 Jul, 2013 10:27
Posts: 3

  Z3 roadster 2.8

Re: Fuse 31 blowing after brake work

Post by firebladeboy »

Ha! I see after looking at your diagram that I misinterpreted "Hot at all times", in this case it means "Live at all times"! 😂

OK. Back to testing! Thanks for the link to that documentation. It's really useful!

Cheers
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