[GoNz0-]

I've a BMW split charge relay to fit, the only problem is I can't find the wiring diagram for it, there's a 2 pin plug to close the relay but finding where on ISTA eludes me, I can't even see it in the special vehicle section. Has anyone got info on where these 2 wires go?
Thanks.

[2013m5]

You should check on ISTA for K9137.

[GoNz0-]

You should check on ISTA for K9137.

All that gave was a wiring diagram for the HUD and engine fan relay, no mention of the aux battery?

[Node]

Maybe because this is the cut-out relay for electric fan!? I never saw any auxiliary battery in E60 from factory...

150A (max rated current for this relay) is WAY too little for auxiliary battery IF that battery is used to start vehicle. IF it's used for something else... then it's some kind of aftermarket thing and all bets are off where this was connected.

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P.S. There can be a second battery on E90, F10 and many other models. Then this exact relay is used for it's isolation. Look for K447 in those.

[GoNz0-]

Maybe because this is the cut-out relay for electric fan!? I never saw any auxiliary battery in E60 from factory...

150A (max rated current for this relay) is WAY too little for auxiliary battery IF that battery is used to start vehicle. IF it's used for something else... then it's some kind of aftermarket thing and all bets are off where this was connected.

---

P.S. There can be a second battery on E90, F10 and many other models. Then this exact relay is used for it's isolation. Look for K447 in those.

There is nothing aftermarket about it, BMW split charge relay just for charging it, it was mainly on police cars, this is a pic of one. It was never designed with starting in mind, more to run accessories, in this case an aftermarket sound system battery.
https://www.realoem.com/bmw/en/partsearc...&q=7661503

I'll see what I can dig up on K447, thanks. I'm trying to find what triggers the relay to close as I expect some sort of engine running trigger.