[V6-12v] OBD1

[James4ihl at aol.com]

Idle Stabilization Valve
The only manual tests you can really do are internal resistance, visual check 
and wiring fault:
1. Pull the 2-way plug off the valve (it's cylindrical vertically mounted to 
the left rear of the throttle valve unit if you're looking at the engine bay 
from the front). Connect a multimeter accross the terminals on the valve to 
measure resistance. Should be 7-11Ohms (it'll be toward the 7 end at low ambient 
temp. toward the 11 end at high ambient temp). If it isn't, replace the valve.
2. If the internal resistance is ok. Remove the valve and check the piston 
slide for scoring, or stickiness, basically anything that impedes easy movement.
3. If those are OK, check the wiring to, and earthing of, the valve.
4. Other tests can only be done with VAG COM in final control diagnosis mode 
(it lets you activate the valve to see if it's working without the engine 
actually being on).

Idle Switch
Manual tests:
This is located within the Throttle Valve Pot
(NB - a condition of this test is that the throttle cable is correctly 
adjusted - assuming it is...)
1. Remove the noise insulation around the throttle valve unit to get to the 
pot.
2. Pull connector off throttle valve pot.
3. Connect multimeter across terminals 4 and 6 (number 6 is the far right 
terminal as you look at the throttle valve pot the right way up).
4. Specification 0 Ohms
5. Open the throttle valve slightly and the resistance should become 
infinite.
6. If you don't get these values, try adjusting the idling switch:
a) remove the throttle valve unit
b) holding it upside down with the wiring connector facing you, loosen the 
two screws on either side of the throttle valve pot unit.
c) twist anti-clockwise until you feel a stop
d) re-tighten bolts.
e) now re-attach the throttle valve unit and go through the same test 
sequence (1-6) above if the values are still not attained, you'll have to replace the 
throttle valve pot

You may also want to check the wiring to and earthing of the throttle valve 
unit before you replace it!

Make sure you replace the noise insulation and any vacuum hoses carefully, as 
vacuum leaks can cause even more problems.

Hope that helps, good luck!
James