[T3] Mystery Miss

[Jim Adney]

On 12 May 2016 at 10:10, Daniel Nohejl wrote:

> Jim, to cut off the motor, I gently touched together the ends of the
> black and white wires....I can´t recall their numbers....16 and 24?. Thing
> is, the ends were covered in several layers of electrical tape.

Yes, 16 & 24 are the power input wires. But they should both be 
white, so perhaps one is just stained a bit. I couldn't make out the 
black in your photo, but one of the wires is in shadow.

Or, Joe made your new harness with a black wire there, or there's a 
hidden splice back where you can't see it. If it's black at this end, 
it should be black at the brain end, too. It it changed color from 
end to end, that sounds odd, so Joe must have put a splice somewhere.

If you're just touching insulation to insulation, that shouldn't do 
anything. In that case, the problem must be a loose connection back 
somewhere you haven't looked yet. I trust the factory crimps, and 
Joe's crimps are probably good, but home-made ones are always 
suspect.

I think you're really close to an answer, but you need to untape all 
that stuff and find out what's really loose. Push and pull lightly on 
each of the crimps to see if one of them has a bit of play. Once you 
find the loose one, you should be able to tighten up the crimp and 
go. I'd still consider some sleeving, rather than tape or heat 
shrink, to slide over those wires, just to keep them from touching 
anything.

If your adaptor wires are M-M, I have genuine M-M VW enclosed 
connectors which would work there.

One of those wires, 16 & 24, supplies the logic portion of the brain, 
while the other one supplies the current to drive the injectors. 
Bosch kept them separate because the logic stuff is sensitive while 
the injectors demand large currents, which means lots of turn-on and 
turn-off transients. Those transients would be likely to upset the 
logic. That's why the main power relay is supplied directly from the 
battery (a "quiet" voltage source) and why power is fed via separate 
wires to the brain.

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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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