I came out this morning 34°F, the truck started to crank but then stopped. Now I have no glow plugs, no ignition, no power to the radio, but the batteries are good. Sounds like a fuse. Which one should I check?

 

Check the fusible links. They originate on the starter side of the starter solenoid [relay], at least on the gas engine trucks. Pull gently and if they stretch, they have burned through and need replacement.

 

You said glowplugs, so I assume you have a 6.9 diesel?

Since your radio doesn't work, I would look at the wiring around the starter solenoid mounted on the pass side fender. That is where power for the truck is tapped off, and there are some fusible links over there like the other poster said. There are no fuses that would kill the truck and make it not run, it's all fusible links.

 

Thanks guys, good tips. I'm also replacing the ignition switch at the base of the steering column. It's old anyway. I'll report as to which is the solution.

 

I checked out those two relays (I guess one is for glow plugs?). Both have solid 12v on one side. I lubed, loosened the posts, checked for corrosion, and re-tightened. Battery posts are clean and tight, with 12.8v in them. And they are relatively new. I'm off to get an ignition switch now.

Odd thing is if I short across the main posts of the starter relay, I would expect the starter to engage. It does not. See this pic. No spark, no action.



Here is the other relay, which I suppose is glow plugs, on the vertical surface of the fender well. That wetness you see is WD40.

 

In that lower picture, if that small wire is a red with a blue stripe, that is your start relay. It should crank if you short the posts. If you get the wrong one, then when you short the posts your glowplugs will heat up.

P.S. See all those many wires on that one large post? That looks like your power distribution powering the truck. There should also be a decent size wire hooked to that same large post going to the battery +. I can't see very well but have you had those wires off? It hasn't been swapped to the wrong post has it?

 

Ignition switch? Do the diesels have the same type of ignition switch as the gassers? No power to the accessories with the key on is typical for ignition switch failure.

 

OK we put in a new ignition switch. It starts to crank then everything goes dead. I think we're dealing with a bad ground cable. Back out in the cold to inspect some more.

 

Checked grounds, tight. Checked cables, frayed a bit against PS fluid reservoir, but sound. Double checked all battery posts...one was not tight enough. Both positive cables go thru that one to get to the starter.


DOH!

I shoulda checked that first. On the bright side, my son learned how to replace the ignition switch and that's one less thing to fail.
.

 

When ground cables are suspect [?], you can take jumper cables and connect to the negative post and attach the other end to the engine block, frame, etc. If, suddenly, the engine starts, then one of the truck's grounds is defective.