E86 Jump leads connected wrong way round

[Atcuk]

Hi I wonder if anyone could shed some light.

I have done a stupid thing, it was cold dark night and connected the jump leads wrong way round - I know it's no excuse!

The jump leads were on for a maximum of 40 seconds before realising. I did try start car while on. The car was trying to start after it happened but didn't. I tried a new battery and same problem. All fuses checked and all good.
1 month later tried again (battery been on trickle charger), engine not even trying to turnover now all I'm getting is a clicking sound and headlights flashing.
The car radio, heating, lights all working.

Could anyone give me some adVise as to what it could be.

Thanks

[anonymous-user]

Starter solenoid.
Or starter.

[dmarkovina]

Starter brushes are known to fail. Just had the same issue on my friend's E91. A local electrician has serviced the starter - replaced the brushes - all good.

[Peanut Gallery]

I did the same (working car had red for negative, black for positive), it blew a very small spade fuse somewhere.

Replaced the fuse, tow started as did not want to faf with jumping again, battery went on to outlive the car.

[Mr Tidy]

Looking on the bright side it looks like your battery may have survived!

I'd check all the fuses then look at the starter solenoid and motor - sadly problems with them aren't that unusual on Z4s.

[Locknut]

I think it's the battery. Things like the radio and lights will come on with a weak battery but the starter / solinoid will just click when they are tried. I presume the lights dim or go off while you are trying the starter and getting the clicking noise.

My sympathies on the mistake with the jump-leads. After more than forty years fiddling with cars I was inclined to look down on people who connected jump leads wrongly. Then one day my wife's car needed a jump start and guess what I did with the jump-leads....

There was a flash and a cracking noise and I spent days kicking myself.

[Collectingbrass]

Did you connect the jump leads at the battery or at the jump start connection point under the bonnet? I'd be tempted to disconnect the battery and try it on a jump pack on the points under the bonnet.