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Re: [T3] FI Relay (was: It's ALIVE!)


On 21 Sep 2003 at 20:17, Aaron Clow wrote:

> --- Jim Adney <jadney@vwtype3.org> wrote:
> 
> > It's also possible that your car is a late enough 71
> > that it has the late 71-72 
> > wiring harness.
> 
> I hadn't thought of that, I guess because I just
> figured that if it didn't have the '72 calipers, it
> was still a '71 model in every other respect. Plus,
> the Bentley says "from August 71."

Yeah, I was thinking the same way, but there's no reason to expect that the 2 
different things changed over at the same time.

> > On those cars, it is possible that
> > there is a misplaced wire on 
> > the starter solenoid. This would have 2 effects: the
> > pump runs all the time and 
> > the FI system runs rich. Sound familiar?
> 
> That was one of the first things I checked. I just
> looked again in the 1972 wiring chart and it's all
> good.

Make sure. The thing that makes the 72 style harness vulnerable is that there 
is a wire from the ignition switch side of the starter solenoid to the computer 
diagnosis plug. This allowed the computer diagnosis machine to actually crank 
the starter to run some of the tests. No other years had this wire, because 
they realized that this created a simple way to hot wire the car, at least the 
starter circuit.

ALL the computer diagnosis years have a +12V wire from the hot side of the 
solenoid, but only the late 71s and 72s have the additional wire to the 
solenoid control terminal. This makes it possible to swap the 2 wires 
accidentally when replacing a starter and create a problem. The problem arises, 
because the FI wire that senses that the starter is cranking connects to the 
solenoid control wire back near the computer diagnosis plug. So if the wires 
get swapped at the starter, the FI thinks you're cranking all the time and 
gives you the starting enrichment it thinks you want, plus it keeps the fuel 
pump running, at least as long as the key is ON.  

> Battery was replaced when I first got the car. The
> damage hasn't gotten worse, but I think I need to
> figure out a way to replace that clamp. 

What you have isn't pretty, but it's actually better than anything you can buy 
new to replace it with. Whatever you do, DON'T buy one of those clamp-on end 
clamps and cut the OE clamp off the end of your own cable. If you really want 
to fix this right, you'll find an old OE one and swap it in. The replacement 
clamp-on clamps only make a good connection.

Note to people scrapping out old type 3s: The battery + cable is a useful and 
valuable part to save!

BTW, I never let anyone else replace a battery for me. Hammering the clamps 
into place is universal among those people, and that's something you REALLY 
don't want them doing to your new battery. You won't see the effects for about 
a year, by which time they'll claim that it's not their fault.

Any time you work on this stuff, you should remove the battery ground cable 
first!  8-0

-- 
Jim Adney
jadney@vwtype3.org
Madison, WI 53711-3054
USA

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