[urq] Oil pressure switch : why 2 ?

[Buchholz, Steven]

... did you check the Bentley wiring for an '85 urq?  I haven't so I don't know for sure, but it sounds like your second car has the "dynamic" oil pressure warning system setup on the block.  The second switch requires a higher pressure, and it is connected to a module that knows the engine RPM ... if the engine RPMs are above a threshold it requires the switch to indicate good pressure.  The high pressure switch closes when pressure is over the threshold.  This is different for the low pressure switch, which closes when the pressure is below the threshold.  

If nothing is hooked up to the other switch it may be that the urqs did not include the required extra module.  

Just about every other Audi in the mid-80s vintage has this system ... 

Steve B
San José, CA (USA)
> 
> Eric's car has two (2) oil pressure switches on the driver side of the
> block; one white, one black (or brown). However, only one is connected
> to the blue-black wire. And I can't find another wire for the other
> switch.
> 
> Bentley shows only 1 switch, a 0.3 bar unit, on track 179. Was this
> second switch installed only to plug an empty hole ?