I have a 2006 530Xi with the N52 engine. I was pulling the intake manifold to get at the vacuum pump and foolishly did not disconnect the negative terminal of the battery. I used aluminum foil to cover the runners and a piece of foil floated down into the engine bay and briefly touched something (I assume it was the terminals of the solenoid/starter unit - I could not see at the time because the manifold was not yet entirely off) and caused a brief spark. Upon putting the car back together, I found no action of the starter or solenoid upon turning the key. While the chime went off, the accessories all worked, but there was no clicking at the solenoid and no turning of the starter motor. I removed the connector that I believe runs from the CAS to the solenoid and checked the voltage there against the negative post used for jumping the car in the engine compartment. It read <100 mV. While leaving the voltmeter connected, I turned the key and found that the voltage never increased (I have read that it's supposed to jump up ~12 V upon the key turn). At this point, I suspected I had fried some or all of the CAS board. Using a long screwdriver and rubber gloves, I shorted the inputs to the starter motor and heard the motor whir. The engine did not turn over (I assume because the solenoid was still disconnected so the pin connecting the gear from the starter to the engine was not actuated). I checked every fuse in the trunk, behind the glove box, and near the computer in the engine bay. I checked them two ways. First, I left the battery connected and checked each side of each fuse individually against the negative terminal of the battery. All fuses read the same voltage on both sides (either 12 V or 0 V). I then disconnected the negative terminal of the battery and checked each fuse again for continuity (using the beeping function of my voltmeter). They all beeped. I then pulled the CAS unit, the computer and sent them along with a key to an outfit down in Jacksonville, FL called "Module Experts" https://moduleexperts.com/ecu-repair/ They checked out the CAS board and found nothing wrong with it. At this point I'm fully stumped! Does anybody have any suggestions for what to try next?

Eagerly awaiting sagacious advice.

Steve

 

im confused...what was the foil for?

either way, check wiring or try new starter would be my next step.

lesson learned tho. always disconnect that battery.

 

Just a WAG but follow the main supply cable to the starter and see if anything got disconnected, the sudden surge of the foil shorting something could have disconnected the terminal this cable is connected to if it was already corroded due to its age.
assuming the starter connection is similar to the E39 that’s what occurred to me where just due to corrosion after 13 yrs the cable just let go due to corrosion without me doing the shorting....lol

 

Foil was to cover the intake runners so nothing fell in there.

 

Thanks, working on that now.