I've now got a related problem:
I just changed the engine in my brown 87, putting in one from my wrecked
silver 87. This replacement motor has been  sitting around for 4 years.
When I start it up and rev it above 2000, the warning light and buzzer
come on. It certainly has enough oil pressure when cold to close the 1.5
bar sensor. (I  checked it with an ohmmeter and verified that it is
working.)
I'm not 100% sure if the low bar sensor is working, but does that even
make a difference with the dynamic warning system? The dynamic system
was working fine with the previous motor.
Any ideas? Ice pick to the cluster?
Al Brase

mark drillock wrote:

> Sorry, Chris but that is bad advice. On the blue foil for 2.1 models
> BOTH oil pressure switch wires connect through the extra circuit board
> in the speedo and then back to the oil light. The cluster will "work"
> with that connector unplugged but the oil pressure warning light WON'T,
> ever! Not even when you first turn on the key.
>
> On the 85 foils with the extra run of blue foil just taped out of the
> way that loose end does not have the actual connector soldered in. VW
> knew that foil was going in a 1.9 engine and made a slightly different
> version for it. That way the same base foil could be used for various
> models but finished differently as required by the engine type.
>
> .Mark
>