John
Take a look at the "IS Relay" circuit board. In our case, the power transistor
was burned so I replaced it and it works fine. Look at the board where
the transistor is mounted. If it is discolored a dark brown/black then chances
are it is the transistor thats bad. I can't remember if it was PNP or NPN but if
you take it to a shop, they can tell you what you need.
Good luck
Larry

John Rodgers wrote:

> How do I trouble shoot the Idle Stabilizer System?
>
> The Idle Stabilizer System on my 88 GL causes the engine to run in a
> jerking fashion. When I disconncted the ISV (idle stabilizer valve) the
> jerking stops. Re-seating the ISC (idle stabilizer control) - behind the
> right rear tail-light did nothing, nor did cleaning the ISV thoroughly.
> Consequently I have been running with the ISV disconnected, but I really
> want to connect it back up since 1) it stabilizes the engine on cold
> starts, 2) boosts the rpm when the power steering limit switch kicks in
> and prevents the engine from stalling when I turn a corner, 3)  boosts
> the rpm to prevent the engine from stalling when the A/C kicks in.
>
> All input on this will be much appreciated.
>
> Thanks,
>
> John Rodgers
> 88 GL Driver