What would make my glow plug controller continually burn up? I've gone through two in the last 5000 miles or so.

Bad glow plugs, for one.

What year is your truck?

'94 4 door hard top with a jasper 6.2L
I have at least two known bad plugs, probably more. I just found them today. The ohms are over 15 on two and 0 on two others. I just picked up a set of AC-60G plugs that I'll put in when I replace the controller. Think that will do the trick? Any tips to get them out without breaking them.

Do bad plugs look different besides swelling? I pulled all mine out - piece of cake. No swelling and no breakage. None on them where really even too tight in the heads, but I did soak them with WD-40 about 2 hours before removing them. They all look okay to me. I'm replacing them anyway but I was just wondering if there was a visual indication that they really were bad.

Other than swelling and glazing, the only other test is the ohms test. Did you happen to note the part number of the ones you took out? If they are 9G or 11G, they are notorious for going bad.

Its hard to read but I want to say it looks like 10G but I can't find any AC delco part to match that (they are definitely AC). Have you heard of a 10G?

Yes, the 10G was very short-lived. Only around for about a year. The 60G is the latest and greatest. Make sure you use anti-sieze on them and most importantly, don't overtighten! I think the torque spec is like 16ftlbs, but check first.

Was the short life due to failure or is that just how it was? It seems that a one year span indicates there was a problem with it that required a new product.

Origanally you said bad plugs "for one". What could be other reasons. I checked all the plugs again now that they are out. There are still two that fail but they don't look any different. I just want to prevent this from happening again so I'd like to check all the reasons the controller could have failed again.

Mostly, failure is due to a direct short if not caused by bad glow plugs. The power stud is located very close to the body and can make contact to ground if your body mounts are compressed or have excessive body flex. Check for burn/arc marks close to where the controller is mounted. Also, use a GM controller, not the aftermarket ones, I don't have alot of faith in the aftermarket ones.

A good test just hook A testlight to B+ and touch the glow plug on the connector, wire connector removed, if the lamp light, plug is good. or you can test them same way at glow plug controller connector and that way you test the circuit at the same time.

Re: Glow plug controller problems
 

It looks like I burnt up another controller - thats the third one. New plugs and no obvious shorts. What else could cause this problem?