1979 633csi temperature switch

[Eohlson]

Found my 4 prong switch (I think) located bottom right on radiator with wites dangling there not attached. There are 2 attachments with 2 wires and 2with 1 wire. I can’t find wiring sequence online
Anyone know

[shogun]

I will move the thread to the 6 forum , wiring diagrams are here http://shark.armchair.mb.ca/~dave/BMW/

[Bert Poliakoff]

Wrong wiring diagram for an e24. Pre 82 is different than post 82 I have no idea what the attachment with 1 wire is for . As you see the switch has only provision for 4 attachments.

[DesktopDave]

+1 The early cars are a lot different than the later ones. If I had to guess, and if I understand what you're saying correctly, I'd think that the pair of dangling wires is probably the hot side. The two single wires are likely the high- and low-speed signal wires. Wiring colors MIGHT be the standard BMW pattern...hot wires are green/brown. Low-speed signal wire is black, high-speed signal wire is green/yellow...might also be yellow/brown. Wire colors tend to fade over time...I'd test them out with a DMM to be sure. Low side signal wire should connect to pin socket 86 of the low speed relay. Likewise, high side signal wire should connect to pin socket 86 of the high speed relay

That 4-prong switch is just two fanstats in one housing. One pair is the low-speed circuit (it's also the A/C signal), the other is the high-speed. Low-speed side should have white plastic around the terminals, high-speed should have red plastic around terminals (sometimes it fades out though).

I don't believe polarity is important since the switches only control the high-speed & low speed relays that actually switch the fan circuit on and off.

Run the engine for a bit to warm up the coolant to test the switch, or remove it from the car to warm it up in a saucepan. The low-speed switch will close at or around 80degC. The high-speed should close at or around 90degC. The switch may have those numbers stamped into it somewhere.