Anybody know what this wire is and where it is supposed to plug in? It looks like a ground wire (it's brown); it has a male connection, and was under the air filter housing. This is a car that has been sitting for a long time -- a 1971 1.7 FI.

Thanks!
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That looks like the wire for the head temp. The only wire I can think of with a male connector in that area.

I'm pretty new at this: what does that look like?

Cylinder head temp sensor is to the left rear of the number 3 cylinder spark plug, which is passenger side rear plug.
There should be a wire coming out of the head tin.

That may also be for the ambient air temp sensor on the passenger side underneath the air cleaner bracket, and underneath the intake runner tubes.

Rich

Trace it out and see where the other end goes.

If it's truly brown and under the plenum area, it may be a ground that became disconnected from the grounding tab on the case

But those are female and his connector looks original.

If its brown and comes out of the ignition harness its the ground for the heater fan, with a male/female piggyback terminal.

The head temp near #3 is already plugged in (I am assuming only one wire goes in there). This wire is also on the other side of the plenum, though just barely.

Where is the ground tab on the case? I don't see anything nearby that looks like a plausible candidate.

I could trace the wire back, I suppose, but I would have to go into a plastic sleeve containing other wires that I would rather not split open if I can avoid it.

Clean off the wire insulation and see if its truly brown. If so, its a ground and in the right area to plug into the ground tab, which "should" be located on one of the bolts that mates the two case halfs at the very top rear of the case. However, The grounds that I usually see on that tab are all white.

Its in the right area to plug into the cold start valve and TS-1.

Looks brown. Is it? Brown, at least original brown, wires are ALWAYS grounds in German cars. ALWAYS. Forget all that other stuff. Tracing a wire isn't rocket science if you have an ohm meter, nor is it all that time consuming. Unplug connectors, test the wires.

The Cap'n

It's definitely brown. I have now managed (I think!) to trace it to the other side of the engine bay, where it is simply cut off. It is paired with a green wire that is also cut off (on the passenger side of the bay); the other end of the green wire seems to go into a large bundle that goes into the relay board. I have not had a chance yet to check any of this with an ohm meter.

By the way, I also checked the white ground (?) wires a couple of you spoke of, and discovered two white wires that join in one female connection and are not connected to anything, nor do I see where they go. There are three pairs of white wires down there, two of which are connected to male tabs on a bracket that is connected to the case, and one of which is dangling. Any help with these?

Another possible clue: I have no heater blower for some reason.

I appreciate all the help so far!

It does seem that the brown and green wire were for the blower motor, according to Dr. 914 on the other site. Thanks for the help with these. Any ideas on where the dangling white wires are supposed to plug in?

Thanks!

Connect the dots. The green + brown circuits feed the heater fan. The fuel injection harness has three pair of white wires as grounds, all three pair should be grounded.

Okay, it does seem that the brown wire is for the missing blower motor, and I did find where the dangling white wire goes -- a hard-to-see tab.

I am still having the following problem: my fuel pump does not prime when the key is turned on. The fuse and relays are good, and the pump works (e.g., when hotwired through the relay pins). I had thought maybe a ground was undone, and that the white wire would solve things, but no luck. (And I did clean the ground connections until they shined.)

Any ideas?

Fuel pump relay gets triggered by a switched ground in the ECU. If you have confirmed the relay itself is good and it works when jumpered (power is good, pump is good) then the problem is either with the relay board itself, the ECU, or the wire the runs from the ECU to the relay board that grounds the relay.

I would start with the relay board. I have had more then one where pins were just lose enough to where the relay would not trigger, but jumpering would still work.

Then work your way back, check the continuity of that single wire that grounds through the ECU, then try a different ECU.

This is helpful, thanks. I'm new to this, though, and am still a bit confused. How do I check the relay board other than making sure the pins are in all the way? (Other than replacing it, obviously.) And what do you mean by "check the continuity of that single wire that grounds through the ECU"?

Thanks....

The ECU gives a ground to the fuel pump relay in three separate instances: 1- upon initial key to on,( about 1-2 seconds),
2- when starting with key to start position, and 3- when the RPMs are greater than XXX RPMs. I think about 200-250 RPMs. If your pump runs some of the time, the pump is not the problem. What triggers the pump relay ground may very well be the problem, the ECU. But if it is intermittent, a bad connection may be the issue. I would start by removing the fuel pump relay and cleaning the male prongs and female sockets and slightly spreading the male prongs. This will ensure the relay is getting a good connection to the relay board. The relay prongs, if turned upside down, are a cross, so slightly spreading them to ensure a tight fit into the relay socket may correct the problem.
Tom

Success! I think it was the ground after all, but I had to go back and recheck and tighten everything else, including the relays, before it would work. I just started from square one again, and I'm not really sure what did it.

Still not yet starting, but at least this issue is resolved....

Thanks for the help!

You said what I was thinking (about the relay sockets and pins). I bought an assortment of different size wire brushes to clean the sockets. Just don't get overly aggressive and taking the plating off the walls, otherwise, they'll corrode faster. Same with the pins. Also be gentle with spreading the prongs (pins) on the relays ... I accidentally broke a couple