Modifying the wiring loom for a Kit Car

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martinclan
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Post Sun Dec 04, 2005 5:52 pm

I am building a 325 based kit and have decided to re-use the original wiring loom. I have sorted much of it out but I have a couple of ouststanding questions for the experts out there! :-)

Un-loading relays. Presumably these disconnect some of the non- essential items from the battery whilst cranking. The question is are they on or off when cranking (In other words do they use N.O. or N.C. contacts)

The connector for my engine wiring harness seems to have a few more wires than in the manual! Has anyone got a better wiring diagram? The donor car is a 1989 325 with cat and check control (if that makes any difference) I don't want to disconnect anything essential....

Cheers

Robin
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Brianmoooore
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Post Sun Dec 04, 2005 11:13 pm

The two unloader relays disconnect power to fuses 16 and 17 (K5) and to fuses 19 and 29 (K7) when cranking.
The cat. wiring is present on all facelift engine looms that I've seen. On most cars the relay, beside the fuel pump and DME relays, is left out.
The oil level indicator will account for three extra wires in the c101 connector.
Any you want to know, give me their colours and the pin number in the C101 if you can, and I'll tell you what their for.
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martinclan
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Post Mon Dec 05, 2005 6:47 pm

Hi Brian

The "mystery" wires are:

YEL-WHT pin 8
BLK pin 9
BLU-YEL pin 14

If you could just confirm that they were for the oil level indicator that would be great - I don't need to worry about them then.

Cheers

Robin
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Brianmoooore
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Post Tue Dec 06, 2005 12:01 am

Pin 8 = white/black = fuel rate to instrument cluster
Pin 9 = black = engine speed to instrument cluster
Pin 14 = black/white = speed signal to instrument cluster

I don't have a yellow/white or blue/yellow shown anywhere on the engine loom, but 14 goes to blue/yellow in the body loom, and 8 goes to white/yellow in the body loom
The oil level sensor is blue to pin 10 and green/yellow to pin 2.
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martinclan
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Post Tue Dec 06, 2005 8:44 am

Hello Brian - thanks for that. I should have said the colours were for the body loom. It looks like I got the main and trace colours transposed. Do you have any idea what is the difference between the engine speed (pin 9) and speed (pin 14) signals? I guess one of them is for the tacho but what about the other one?

Cheers - Robin
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Brianmoooore
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Post Tue Dec 06, 2005 9:28 am

Black wire is the tacho signal.
Never really thought about the speed signal before, but looking closely at the wiring diagrams, it appears to be a cleaned up version of the road speed signal from the diff, and is going from pin B10 (white plug) of the cluster back to the ECU. What the ECU does with this signal, I don't know.
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martinclan
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Post Tue Dec 06, 2005 3:47 pm

Thanks again

I hope I don't need the road speed signal then as I don't have an instrument cluster! (Aftermarket instruments) I guess not because I am not the firts person to have used an E30 for a kit...
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