The truck started to act up recently , refusing to start on the command start key fob, but starting fine with the key. Now it is acting hard to start with the key too. I noticed the glow plug light is going out sooner than normal when it doesn't start. If I hit the crank as soon as the instant goes off she starts fine, if the light stays on for a long time like it normaly did. Most times when it doesn't start the glow plug light cycled very fast, and it's a no go. This makes me think it is what ever controls the glow plug is causing the trouble starting., but what is this and where is it located, and how do you test it?

 

if you have any problems in the GP system the key fob command start will not work you need to check and teast all the leads to the GPs then the GP controler is where a distributor would be it has the two heavy gauge cables running in and out of it and if you decide to replace the controler do not use anything besides AC/DELCO or go to NAPA for one anything else and you will regret it

 

The ECT in the coolant crossover is what tells the ECM engine temp and the ECM activates the glow controller.

AC Delco ONLY for all electronic replacement parts even if they require special order.

Get a quality scan tool hooked up and see what temp the ECM is reading-a faulty coolant sensor could be telling the ECM that the engine is warm causing a short glow cycle.

As directed check for power at all glow leads-unplug the glow plugs and jumper the heavy terminals on the glow relay and check with a test light or meter.

Also if glow plug age/performance is unknown-replace with Bosch Duratherm glows.

 

I have some testing to do tomorrow I guess. It is going down hill fast on me, and yesterday it was near impossible to start. In desperation I pluged in the block heater for half an hour to make it start and it did. {When it is warmed from running it starts instantly.} It used to start instantly even well below freezing.
Winter is coming and I am in a world of hurt if I can't figure out the issue causing this.
What voltage should I get at each plug? and at the controller?

 

Should be battery voltage on both heavy lugs when jumpered and at all glow plug leads.

Do not jumper relay with any glows still plugged in-some older glow plugs swell if activated too long making removal very difficult often requiring this expensive tool:
second from bottom:
http://leroydiesel.com/Accessories.html

 

That is pretty sweet racer gonna do a turbo and exhaust here soon and was wondering how to do the boost gauge and any clues where to get pillar pods for a 1993 in red trim??? the reason I am asking racer when I did the radio install into the center of the dash all I could get was blue

 

A lot cheaper to drill and pipe tap your upper intake for a hose barb-that said I have the boost bolt.

Also posted link for info about the glow plug extractor so trying not to ruffle any feathers about a non supporting vendor.

 

I did some probing and voltage tests and all seemed good. Wiggled the wires at the relay etc . Pulled every fuse in both fuse blocks and checked for condition , all were good . Now all is back to normal , and it starts like a champ. I have no Idea what was causing the problems, or what fixed them, but it works. I put some oil on the terminals of the relay as they looked like they were starting to corrode, and figured a squirt couldn't hurt as prevention. Perhaps it was a poor fuse contact??