'85 with 305. With key in run position, engine not running, AC on or off, I have 12Volts at idle speed solenoid connector. With the engine running and AC on or off, I have 0 volts. I am not sure why I would have the 12V when the key is in the run position, engine not running and the AC is off? The AC compressor cycles normally. Ideas welcome.
Thanks
Robby

Check the fast idle relay. It's located on the passenger side, next to the radiator overflow bottle. The Delco part number is 14078924. It has a five pin connector. I bought a new one at a Chevy dealer. This part is probably used on quite a few GM vehicles....Doug

You do not need to have the AC on to have the Idle Stop Solenoid energized. The Idle Stop Solenoid can be energized two ways. One way is, when the Fast Idle Relay is de-energized and the AC is turned to Normal or MAX. The second way is if the Fast Idle Relay is energized by the Electronic Control Module (ECM).

Ernie,

Thanks for replying to my post on the 1985 AC idle speed control issue. Is there an easy way to check the fast idle relay? I looked at the schematics we have on the site but they don't show the relay circuit. Hoping you might have the diagram or advice on checking the relay. And can I assume that the relay works as a switch - activating the relay from either the ECM or the AC switch.

Thanks
Robby

Connect a wire from the battery to the connector on the fast idle solenoid with the engine running and the AC on. If it activates then you can be pretty sure your relay is bad.....Doug

Here is the schematic for the Idle Stop Solenoid (ISS). Click on it to make it larger.

http://members.cox.net/87elcamino/pictures/idle_stop_solenoid.jpg

Just a followup to my original thread that my problem was the Fast idle Relay. (it was sticking). Thanks to all who replied.

YOU GUYS ARE GOOD ! I CAN NOW FIX MY 84SS EL-C AND WON'T HAVE TO TURN THE AC OFF AT LIGHTS TO SLOW DOWN THE IDLE AND BEFORE I TURN THE ENGINE OFF TO KEEP IT FROM "RUNNING ON". . . . LIKE I DO ! BARRY-MARYLAND