Idle stabilization control unit pinout?

Antti Piirainen antti.piirainen at
Tue Jan 27 16:29:35 EST 2004

a4kcstq at wrote:

> You've got them correct so far. I've added some info below. This is reading from the '86 5kqt diagram out of Bentley.


I spent tonight measuring and testing the different ISV circuits, and 
meanwhile learned a lot from the control unit's operation. The problem, 
by the way, was a dislocated spring in the ISV itself, causing it to 
open wide at the threshold voltage (which apparently was around 1,6 
volts), when it should have not.

> I'm not sure about your control unit. I thought they used 2 relay sockets, not 3.

Physically it does. However it's three units wide, and while actually 
connecting to relay plates 8 and 9 in my car, it takes up the space for 
the non-existing plate 7 on the relay map, thus marked "7-9".

> What type of car is it from?

An '87 Coupe quattro with a naturally aspirated KV engine, ie. CIS, 
vacuum controlled advance, no cat and no lambda. Thus, no ECU.

Antti Piirainen
87 Cq

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