First of all, I recommend you download this file and read it back to front.
https://f01.justanswer.com/RbZmAlHy/This+is+how+you+wire+up+a+1UZFE+Engine.pdf
Next, download this file and be sure your model of E36 is included
drive.google.com
The BMW X20 Plug has many pin configurations based on your build date and original engine, but they all basically have the same wires in them. The wiring colours will give it away.
The input wiring into the X20 from your 1UZ harness are:
- Tacho signal - black
- Coolant temp sender - brown/violet & brown/yellow
- (you'll need to fit the OE BMW sender as the gauge is calibrated to it)
- Oil pressure switch - brown/green
- Check engine light - grey
- Fuel pump relay trigger - brown/green
- Alternator light - blue
- Reverse light signal - blue/yellow
The output wiring from the X20 into your 1UZ harness are:
- Ignition power - thick green
- Starter - black/yellow
Note that these are the X20 wiring colours I used. Yours may be different so please check before you go cutting/soldering.
Main Relay
- Pin 30 - I used a standalone constant 12v+ cable across from the jump post.
ECU Batt input is crimped into this wire.
- Pin 87 - Output power to the igniters, injectors, coils, O2 sensor heaters, purge vsv, and anything else powered by the MREL
Each output was fused individually so that one short doesn't take out the whole circuit.
- Pin 85 - MREL output from the ECU
- Pin 86 - ground