while trying to start my truck I noticed a clicking noise coming from the relay for the glow plugs. When I tested them out I found the glow plugs to pulse with the clicking. What's going on and how do I fix it. I already changed the plugs and the relay.

 

what year is the truck ?

 

the truck is a 1988 F-350, 7.3 diesel. I was told I have two relays on the truck from pep boys. I replaced the cheap one first but I was also told the other one costs around $200. A friend of mine told me to go onto a ford web sight to ask questions. He is a diesel mechanic and has not seen this before. By the way, thanks for answering back.

jeff

 

there are a few questions to be asked. but first, check the ground on the glow plug controller over the passenger valve cover. when the wait to start light goes out, the controller will click for a few minutes to keep the plugs hot till the engine gets some heat in it.
what type of glow plugs did you use?? i hope it was the MOTORCRAFT/BERU plugs. any other plug will only give you trouble with fast burnout, and swollen tips that may break off when trying to remove them.

and a better forum for most questions on this truck will be the pre powerstroke diesel forum farther down on the page.

 

the glow plug module activates through you ignition switch and uses a temp sensor to command how long to turn on your g/p's-usually 10-15 sec on time then it will cycle to keep the g/p's hot. if you have some bad g/p's it will start cycleing sooner

to check your g/p's use a test light, unplug the wire at the g/p you are going to test; connect the light at the battery pos. and touch the top of the g/p. If it lights your o.k., also most the most recomended g/p is the one from motorcraft
there is a forum that deals exclusively with these 6.9 & 7.3's just scroll down a little further to the diesel area and you'll find it. Alot of topics there dealing with your questions/problems and a big welcome for you also