Electrical Problem (car dead)

#1

Unfortunately a seemingly innocent bump with Simon at the last race broke the middle grille and lodged it in the rad fan which led to an electrical meltdown once we got back to the paddock.
Currently the car is completely dead; nothing happens when you turn the key to the on position (including no dash lights) so something got fried. When the wires started smoking Kyle was heads up enough to kill the fan switch so it didn’t just melt things until it died.

Looks like the guy we bought the car from didn’t properly fuse that manual fan control switch which lead to this whole problem (not to mention the undersized wires). The wires were run separate from the car harness so that means we are lucky that it’s just didn’t melt into everything. Main damage only appears to be some other manually run wire for the oil pressure & temp gauges but that’s doesn’t explain why the car is now dead.

Any ideas what goes first?
No underhood fuses are blown that I can find. There’s power on both sides of the kill switch (when it’s on) so that’s not it. About done checking things under the hood and about to move under the dash. Is there an under dash fuse box as well?

Going to check out the ECU in another car later this week.
I’m not familiar with BMW electrical but I was surprised to not see a main battery fuse. The battery + appears to run directly to the starter and then direct to the alternator. Is there normally a fuse on the distribution block? (replaced by the kill switch on our car).

Ideas?

#2

The smaller of the two wires that connect to the battery, which powers the engine management and some other stuff, does have an inline fuse in the wire. If the fan power was going through that wire, rather than the main power lead, it could have blown the fuse.

#3

jlevie wrote:

Not finding that fuse. What does it look like? in the cabin up under the dash?

edit: Found a blown fusable link back by the battery in that small wire. Need to find a way to jumper that’s the only problem.

#4

Jumped that link (with a 30A fuse) and all is good!!! :slight_smile:

Just need to redo some wiring and get that link (or replace it with a circuit breaker).

Anyone have any idea what amperage that fuseable link is?

#5

You found it. I don’t know what the rating for the fuse is, but 30a sounds about right based on the wire size. I’d replace the blown in-line fuse with a fuse holder mounted close to the battery. You are going to need to do some clean up and rewiring of the fan. It should be powered via its own 30a fuse run from the main power point in the engine bay and not powered from the engine management lead.

#6

Fan wires post meltdown: