No electrical power

R

Red Panda

Member
Hi all, I wonder if anyone can assist me with this please?
I have an 07 Z4M

I have zero electrical power to anything, which came about when my battery needed charging (car not used for a while). I removed it for charging and linked the pos and neg battery terminals so I could maybe unlock the boot if it shut and latched, which it then did!

I put battery power through the positive terminal post under the bonnet and earth, this sparked - I thought not good, probably as I didn't have the battery there a resistor! All fuses are good (glove box and ones next to DME relay, no power! What have I blown?!?

Any help much appreciated 😬
 
You linked the battery terminals? Why?
I would start by checking that your battery charger is still working!
 
Because I thought this would create a circuit if needed to activate the boot release - not a good idea in hindsight. Battery and charger good.
 
So you joined the +ve and -ve terminals in the boot, then put power through the terminals under the bonnet ?? :cry:
No wonder it sparked.
There would have been a MASSIVE current flow, so I'd guess there is a big fuse somewhere that has blown. Maybe fuse 54 or 58 ?
 

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..... I've checked all fuses - they are good. When I connect the battery, I get 12v between the positive terminal under the bonnet and earth, so the circuit still exists ( not blown away).
 
The main fuse is on the battery junction box cable. You've probably blown this but I'd be checking every other fuse too, you say you've done every one but there are more than just the glove box.

The bonnet terminals connect straight to the battery so they don't indicate anything about any of the other circuits.

Or maybe get someone competent to do it before you break something else :lol:
 
Something can’t be right here. If you joined the positive and negative battery terminals without anything in between, you would know about it. Big spark and probably melt the connector. This is unlikely to have killed anything in the car, but may have killed your battery. Have I misunderstood what you did?
 
Thanks for the info. No you have understood exactly. No power anywhere. Very hard to access the battery area also - as the boot is locked as a bonus. Battery is at 13v. I've checked the fuses by the DME relay by the ECU - all good. The battery junction box fuse (the one which is part of the battery terminal connector?) I was thinking must be good as I'm getting 12v when I connect the battery under the bonnet?
 
Try a replacement battery and check every fuse. If you have no joy then I think you need to get it to a proper auto sparks before you do any more damage.
It might be expensive now but save a fortune if you fiddle on!
 
You can open the boot with the key.
Don't give up just yet, I think Scooba_Steve and Old-Duckman are right. Change the Main Battery Fuse (Fusible Link).
And...write 100 lines "I must not join a +ve wire directly to -ve again" :D
 
My car was dead but had a fully charged battery showing 14.1v at the charger. Turned out it must have been low on amps. A new battery from 'Tanya' delivered the next day at an unbeatable cost and car was fine again.
 
Red Panda said:
Hahaha, it will be etched on my mind for ever. I'll let you know what the final outcome is.
Click to expand...
At least it's not etched on your nads!

Just had a look at the wiring diagrams. The jump terminal is direct to battery and unfused.

Battery B+ goes direct to F102 40 A and F100 250 A fuses. They are in A400 and are worth checking, I think you've blown the 250 A fuse. Hopefully that hasn't caused any other issues but if none of the A41 (glovebox) fuses have blown then happy days as these are all downstream of the main fuse.
A400.png
 
With the above in mind - can you do a continuity test from the end of the battery terminals and let us know the results please .

It’s a cheap option than the Fuse change !
 
ronk said:
With the above in mind - can you do a continuity test from the end of the neg battery lead and an Earth point on the body? Let us know the result please .

It’s a cheap option than the Fuse change !
Click to expand...
Not sure how that will prove the fuse on B+. Just test continuity across the fuse :-?
 
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