Glow plug controller

[Rob 85K5]

Can you bench test the 85 and up style GPC? Had to use the screwdriver to jump the posts this weekend, after that it remembered to work.
I have one off of a junker, is there a way to test it instead of droping $70 on a new one?

How much to go manual?

 

[6.2Blazer]

There's a pretty simple diagnostic tree you can follow to verify what is going on...I've got the cheap Chilton's or Haynes manual that had it, and it was a copy of the tree found in the factory manual. I multimeter and about 15 minutes confirmed the issue on two different occassions (one time was just the temp. sensor, the other time it was the controller).

If the temp sensor is bad and showing too high of a temp then it won't trigger the controller. Quick check is if the glow plugs won't come on just unplug the sensor (located on the front pass. side of the engine). The default open on this goes low = triggering the controller.