Electrical problem 2006 Z4 M

mbeers61 · Post by **mbeers61** » Wed Jan 13, 2021 1:35 am

Hey Guys,

I bought a 2006 Z4 M last spring knowing that the infamous roof motor needed to be replaced. I put off the job until winter. The motor replacement went fine and we got most everything put back together, tested the roof and it was going up and down as it should. Then everything went dead electrically. At first I thought we just killed the battery so I took it out, charged it up and had it tested. They battery is good. We did notice that the rubber insulation on what I think is the trickle charge connection had melted a little. I reinstalled the battery and still have no electrical power at all. The car does not turn over and no lights work at all. I checked the BST and it doesn't appear to have been activated. Is there something else that could have been tripped or shorted out that I'm missing?

Thanks!

Mike

ph001 · Post by **ph001** » Wed Jan 13, 2021 7:15 am

I think you probably need to check the main large fuse links that are ‘hidden’ in the fuse box under the glove box (lhs of pic below)...

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mbeers61 · Post by **mbeers61** » Thu Jan 14, 2021 1:37 am

Hey Thanks!
I dropped the glove box so I have access to the fuses. Are you talking about those 40 & 50 amp fuses on the top row?

ph001 · Post by **ph001** » Thu Jan 14, 2021 8:02 am

Those, and the large black ones on the left that run from the main battery feed. Hard to understand how you could blow one of those just by operating the rooof motor though

john-e89 · Post by **john-e89** » Thu Jan 14, 2021 2:50 pm

I can’t for the life of me remember what, but there’s either a fuse or a relay just before the battery on the M, it’s tucked down behind it so you’d need to remove the battery to get to it. Also the ignition switch fails on these too, mine went and the symptoms were like a knackered battery.

ph001 · Post by **ph001** » Thu Jan 14, 2021 3:12 pm

john-e89 wrote: ↑Thu Jan 14, 2021 2:50 pm I can’t for the life of me remember what, but there’s either a fuse or a relay just before the battery on the M, it’s tucked down behind it so you’d need to remove the battery to get to it. Also the ignition switch fails on these too, mine went and the symptoms were like a knackered battery.

I think the main battery fuse is what the OP is referring to when he says he has checked the BST (battery safety terminal). The ignition switch certainly has come up before but you would expect that to only affect ancillaries that come on with the ignition.

I was under the impression the entire car was dead - perhaps the OP can clarify? For example - does the central locking work??

john-e89 · Post by **john-e89** » Thu Jan 14, 2021 6:40 pm

ph001 wrote: ↑Thu Jan 14, 2021 3:12 pm
john-e89 wrote: ↑Thu Jan 14, 2021 2:50 pm I can’t for the life of me remember what, but there’s either a fuse or a relay just before the battery on the M, it’s tucked down behind it so you’d need to remove the battery to get to it. Also the ignition switch fails on these too, mine went and the symptoms were like a knackered battery.
I think the main battery fuse is what the OP is referring to when he says he has checked the BST (battery safety terminal). The ignition switch certainly has come up before but you would expect that to only affect ancillaries that come on with the ignition.

I was under the impression the entire car was dead - perhaps the OP can clarify? For example - does the central locking work??

Yes that’s it, sorry, I missed that on his post....

Clarification needed on the locking as you say, if it’s working the ignition switch can cause a lot of failing battery symptoms.

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