[T3] car died on way home

Jim Adney jadney at vwtype3.org
Fri Apr 13 20:05:21 PDT 2012

On 13 Apr 2012 at 19:16, Bryon Garvin wrote:

> Replaced the relay with known good relay.  Same problem.  1 click only,
> from under back seat.

Try this: Turn the key on, and verify that both coil terminals (in 
the plastic housing) are "hot" (leave the wires plugged into the 
relay.) If they are not hot, the problem is in the power source to 
the relay, starting in the main power relay and then the wire from 
that relay to the fuel pump relay.

If that's okay, go to the engine compartment and use a wire to short 
between ground and the connectors inside that 2-wire connector in the 
engine compartment. No need to unplug those wires or remove the 
brain. That should make the pump run.  

If it does, remove the brain (again) and, under the same conditions, 
short wire 19 to ground. That should also make the pump run.

If either test fails, the problem is between that point and the 

If these all work, maybe you can find someone locally who would let 
you use their brain for a test. You could actually use ANY Type 3 
brain, and probably any D-Jetronix brain, but I'm not completely sure 
about that. I don't recommend starting and running your engine like 
this, but you could certainly verify correct pump operation.

There's still a very small possibility that there's a problem inside 
the wiring harness that responds to the bending that's necessary to 
get the brain in and out. I don't think that's at all likely, but it 
remains a possibility and that could be confusing the diagnosis.

Finally, I doubt if you damaged anything by poking inside the brain. 
It could be a bad transistor, but it could also be some other 
component in that circuit.

You DID tighten up the #19 connection to the PC board, didn't you?

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

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