[76m2002]

Does the factory m54 oil pressure switch have two wires? I’m transferring over the wiring harness from a dead engine to a replacement engine, and included the oil distribution block for my oil pressure sender and Temp sender. In the pic the orange wires connect my gauges to the oil pressure sender and the oil temp sender. I’ve got two leftover wires in the factory harness, a black and a black/yellow wire. I think the black/yellow is a single wire for the factory low pressure switch which I'll attach to the empty terminal on the sender, but can't remember what the black wire is for.

 

[BaliDawg]

Look up the wiring diagram on bmwteka.com.

 

[MrMCar]

The factory sensor in the photo is an oil temperature sensor. Used by DME for making decisions about Vanos thresholds.
The VDO sensor (round can) is one we very often use. It has two terminals. One is for the matching cockpit pressure gauge, and the other should hook directly into the oil pressure warning lamp (one pin connector) so that the RED oil pressure warning light continues to function.

HTH?

 

[76m2002]

Hi Don,

Sorry for the confusion. I'm clear on the two sensors in the pic, and have the first terminal on the can hooked up to my gauge. My problem is figuring out the wires that are coming out of the factory harness for the oem pressure switch. In this pic I think the yellow/black wire (indicted with yellow arrow) is the wire for the oil pressure dash light, and I'll connect that to the unused terminal on the can sensor. However, I can't remember what the black wire is (blue arrow). Should there be any other wires in the factory harness to the original oem oil pressure switch?

 

[MrMCar]

Need the last 7 of the vin for the harness you're using...

 

[76m2002]

You bet: EZ15160

Thanks!

 

[BaliDawg]

You bet: EZ15160

Thanks!

As I said back in post #2, look up the wiring diagram on bmwtek.com.

 

[MrMCar]

My diagram (sometimes wrong) shows a BN/GN brown/green wire for the oil pressure light.

 

[76m2002]

Thanks! So that's probably my black/yellow wire.

 

[76m2002]

This is starting to make sense now. I think the black wire is leftover from a previous installation 15 years ago where I ran the wire for the pressure gauge back through the factory wiring harness to the rear of the engine.
Thanks for helping a mis-firing memory!

 

[MrMCar]

So perhaps a prior splicing event?
Because a Bk/Yl wire is almost always a starter trigger (solenoid) wire.

 

[76m2002]

You are right, Don. It looks like the starter lead got flipped up when I transferred the wiring harness to the replacement engine. I got the orientation figured out using your color codes, and the wires make sense now.
Thanks!

 

[MrMCar]

You are right, Don. It looks like the starter lead got flipped up when I transferred the wiring harness to the replacement engine. I got the orientation figured out using your color codes, and the wires make sense now.
Thanks!

Yeah up until the end of the E36 chassis, BMW was great about keeping wire colors the same.
Fuel pump was always Gn/Vi. Starter was always Bk/Yl. Now any color goes. Pity.