MyE28.com

I found some old notes I had from '04 when I wired an e30 harness into my 1985 528e. The harness was from a 1987 325i. I believe these splices would be the same for all e28's and six cylinder e30's but I no longer have a copy of the ETM so I can't verify that.

1985 e28--->1987 e30
Pin 1--------->Pin1.....To inst. cluster charging indicator lamp
Pin 2--------->Pin 2....To check control, static oil level sensor
Pin 4--------->Pin 4....To cluster, coolant temp signal
Pin 6--------->..............Not used with e30 FI (integrated idle control)
Pin 7--------->Pin 13..Fuel pump control
Pin 8--------->Pin 18..To starter, from ignition
Pin 10------->..............Not used on non-airbag cars? (would go to pin 20?)
Pin 12------->Pin 7.....12V to ign coil
Pin 13------->Pin 10...To check control, dynamic oil level sen.
Pin 14------->Pin 5.....To cluster, oil pressure warning lamp
Pin 15------->Pin 11...To cluster, SI reset
---------------->Pin 16...Unused
---------------->Pin 20...Unused

The e30 harness also has a few extra wires coming through the C101 to support the additional features of Motronic 1.1/1.3:
Pin 12--->To inst. cluster for "Check Engine" light
Pin 6----->To a 15A fuse, hot in run or start, for the oxygen sensor heater relay.

The 02 sensor heater isn't critical, but you should splice it in. The check engine light can be helpful for troubleshooting but you would have to run wires to the cluster and install a "prizm" in the cluster from a 1988 528e with a "Check Engine" indicator. I'd just wrap it up in some electrical tape and tape it to the harness.

Thats most of the wiring. You still have the C103 to deal with in the glovebox. That connector carries the engine speed and fuel consumption signals to the cluster, the A/C-on signal to the ecu for idle control and most importantly a 12 volt signal to the ECU from the ignition switch that lets the ECU know its time to wake up. I'll add those splices to this thread when I have a chance to look them up.

Thanks Turbodan that neatly confirms all the info I have put together from various sources. It noce to here it fro soe one who has done this though.

bm0p700f wrote: It noce to here it fro soe one who has done this though.

Translation:
"It's nice to hear it from someone who has done this, though."

I really should learn how to type.

So if I take a 3' jumper wire from the battery to my (84 533i) pin # 8, I can turn the starter over?
And #7 run the fuel pumps? And #12 power the coil?
Therefore start the car from the engine compartment if I feed power to all 3? Will the ECU be annoyed at me about this?

j24sailorboy wrote:So if I take a 3' jumper wire from the battery to my (84 533i) pin # 8, I can turn the starter over?
And #7 run the fuel pumps? And #12 power the coil?
Therefore start the car from the engine compartment if I feed power to all 3? Will the ECU be annoyed at me about this?

You're probably thinking of the diagnostic connector. The C101 connector is the rectangular connection where the engine harness plugs into the fusebox.

From the diagnostic connector you can crank the engine, but you wont be able to start it. Unless the ECU is getting a "run" signal from the ignition switch the ECU doesn't wake up. BMW routed that separately through the C103 connector under the dash. Maybe the point of that was so you can't get the car started from under the hood.

Turbodan, thanks for this write up (all those years ago). I'm trying to do nearly the exact same thing now, which is to wire up a harness from an 87 325is into my 86 528e as part of an e2i swap. Does anybody know what connections need to be made/spliced in from the ecu block to the instrument cluster? Thanks.