What is the T7a/6 wire for ? ( black/red) 1985

[ALIKA T3]

Hello folks!

I'm converting an 1985 Westy from 1.9L WBX to 1.9L M-Tdi.

I have a connector in the connectors black box that I believe is called T7a ( the same one that has the wires for the coolant level sensor).

For the life of me I cannot find and trace the Red/black wire from that round connector on the Bentley. I can find from 1 to 5 but not number 6 wire.

The engine end of that wire is gone with the wiring harness and engine onto another van, so I don't know what it was...

I'm using a pig tail from a 2.1L harness and I know the black/red wire is going to the ignition relay box long the red B+.

Thank you for your help

Shootz!
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[Steve M.]

I just went through the T7's and from my notes on 1988-91 it is going to the Digifant ECU Terminal #1. This was on page 97.206

I know it is later then your '85, but seeing how they try to follow through during the years it might be going to the same location?

1987-91 notes:

(I do know what #4 is, just haven't written it down yet.)
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[djkeev]

I was thinking similar, I have a late 1986 production.

I know that the late 1.9 units have the newer 1986 single TPS switch.

Page 97.72 (early 1986) shows the Red/black wire at 7a/6 current path 24 fed from the 50 terminal on the ignition switch current path 8

VW slides changes in and not always at exact chassis number/model year breaks, Hence the Beetle based book "Progressive Improvements".
Is your unit a very late production 85? They may have installed the newer body harness but did not utilize that wire for your unit?

1986 2.1 eliminated the ignition module that the 1.9 utilized.

1984 didn't even have a T7a plug.

Dave
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[ALIKA T3]

Thank you guys!

You are correct, 1984 didn't have a T7a, I found that name from my notes when I did a Subie conversion in a 87. Probably why that connector/wire doesn't exist in the Bentley.

So what I did is follow what you said about the ignition switch. It goes there on the 1986 and up. If I go on the 1985 diagram, I can find the wire but only at the ignition switch, but it goes nowhere

I don't understand the function of the 2 wire plug for the relay box in the engine bay for a 2.1L : one is B+, the other would be a IGN+ ? ( after contact +) ?

The van is in pieces or I would just try it and see....

Thanks again
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Syncro transmission upgrade parts in the Classifieds.
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http://www.thesamba.com/vw/forum/viewtopic.php?t=416343
Syncro http://www.thesamba.com/vw/forum/viewtopic.php?t=4...num+gadget

[crazyvwvanman]

That red/black goes to the wbx FI harness to tell the FI system that you are trying to start the engine. It comes from the circuit 50 wiring. Circuit 50 is from the ignition switch starter contact to the starter solenoid. The exact path varies by model/year.

Mark

[ALIKA T3]

[leecat]

This thread was immensely helpful, guys! That T7a/6 almost drove me nuts too just now. I know it's an ancient thread, but what happens if the FI system is NOT told that you are trying to start the engine via momentary power to that line?

Update - apparently nothing! Van starts and runs just fine with the red/black wire cut. Oy vay, Volkswagen! You drive me nuts sometimes!