1988 M20 starter/solinod electrical connections

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ChuckinDallas
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Post Sun Jun 11, 2017 2:37 pm

Greetings all from Dallas, Texas, USA.

Almost (really?) finished with manual transmission replacement. Hooking up starter wires... but have terminal and cannot find the wire supposed to go there. My bad, of course. Thought I had properly marked everything during disassembly - which ocured 2 months ago. My version of the Bentley tells about and shows picture, with the caption "1988 - 1990 six cylindar engines have a 4th terminal, not shown". Great. Discovered this at 11:30pm local time....

Anybody got a link to drawing / picture/ commentary as to how to hook this up? HELP!!! Please.
Chuck
:(
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Brianmoooore
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Post Sun Jun 11, 2017 2:56 pm

If your car starts and runs, the missing wire is a black/green one that connects to relays K5 and K7 via pin 15 of the engine loom C101 plug and socket.
If you have a facelift starter motor with facelift engine loom, you should have two wires going to the largest outer solenoid terminal - one from the battery and one to the alternator.
Nothing, other than the factory fitted link to the motor body, should be connected to the other (inner) large terminal on the solenoid.
A black/yellow wire from the loom should go to a smaller stud on the solenoid, and a black/green wire, also from the loom, should go to the smallest stud.
Note that the colours of these two wires will be obscured by a black outer sheath, and a pre facelift starter motor won't have the smallest terminal. Similarly, a pre facelift loom won't have the black/green wire.
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ChuckinDallas
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Post Sun Jun 11, 2017 3:16 pm

Thanks Brianmoooore.... as further background:

This is a race car I've owned for a few months. The frame is an '85 Coupe that came w/ the etta motor. The car came with an M20 from an '88 325i. There are both wiring harnesses still in the engine bay but the etta stuff is in a few coils w/ zip ties holding them out of the way.

I have a 4 pole solenoid, the copper mesh hooks right near the starter, have a smaller wire (don't know color & car is at Dallas makespace about 10 miles away). The biggest diameter pole has the red from battery and black from alternator on it. At the top I put a smaller wire that was unlabled (hate it when I do that!!!). Then tried the key - heard the starter spin but it didn't engage. Upon closer look realized there was a pole below the thickest one that clearly had had a wire on it, but no loose wire is anywhere to be found nearby.
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Brianmoooore
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Post Sun Jun 11, 2017 3:54 pm

'85 car won't have the green/black in the body loom, so there's not much point connecting it to the starter motor, even if it's present in the engine loom.
The fourth terminal has nothing to do with making the starter operate, but is effectively connected to the inner large terminal of the solenoid/ starter motor, so if you've connected the black/yellow (start signal from the ignition switch) to this terminal by mistake, the motor may well spin, but the black/yellow wiring will be getting very hot, very quickly.
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ChuckinDallas
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Post Sun Jun 11, 2017 5:47 pm

Thanks - going to spend the afternoon w/ the car & will have pictures later...