Strange wire.

Dec 20, 2004 9 Replies
S

I've just changed the heater hoses on my '87 740 (B230). I now find I have a wire with no home. It emerges from a small sender at the rear of the block, just below and forward of the heater hose stub under the inlet manifold, and has a shrouded spade connector on the end of it.



It's not the thermo-time switch, not the temperature sender, nor the anti-knock sensor. Everything seems to be working OK, and to be sure, judging by the crud around the connector on the end of the wire, it hasn't been connected to anything for a long time. There is nowhere obvious for it to go, with no corresponding connenctors anywhere near it that I can see.



So, what is the sender? Should it be connected, or is it redundant?


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B

Stewart Hargrave decided to add:

You answered your own question...

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J

It's a diagnostic connector, it allows the dealer diagnostic machine to read the crank angle.

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~

i have one or two of those wires in my 1993 940t... they are for running diagnostics and stuff...not to worry my mechanic esplained' to me...

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S

OK. I thought my car (UK spec) pre-dated diagnostics.

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S

Ah yes. But it's a worry when mechanics say that.

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J

message

87? The PC "arrived" about '80 but that was fairly late in the electronics era. My '80 Volvo also has spare wires everywhere... and electronic ignition I think. I had a '72 cortina with a printed curcuit behind instrument panel, admittedly only to make the wiring neater but a lot of the engineering methods where there even then. Not very familiar with engine diagnostics but there must have been some sort for as long as cars have had electric lights. Ah every generation thinks it invented the light globe...
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J

The diagnostic sensor on the crank was there at least as far back as '78 in the US cars, and probably earlier.

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R

On some turbos the rear block sensor worked for cold enrichment, since turbos have no throttle switch enrichment position. On some ACC/ECC cars the rear block sensor provided a ground that inhibited heater fan operation in all positions except defrost. The turbo system used a grey wire. The climate control systems used a pink wire.

Bob

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