Strange wire.

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?
--

Stewart Hargrave


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Stewart Hargrave decided to add:

You answered your own question...

 

??

--

Stewart Hargrave


For email, replace 'SpamOnlyToHere' with my name

 

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

 

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...

 

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

--

Stewart Hargrave


For email, replace 'SpamOnlyToHere' with my name

 

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

--

Stewart Hargrave


For email, replace 'SpamOnlyToHere' with my name

 

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...

 

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

 

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