Afterglow cycling won't stop

[quickster45]

Hows it going all. Now this started about 2 weeks ago. After start up, the WTS goes off, but the volt gage keeps bouncing back and forth. So that would be the afterglow cycle,right? It used to go off right away, but now over the 2 weeks it's gone from 1 min to 2 min. Now today it stayed on for my whole ride--10 min. Bouncing the gauge back and forth. Anybody know if this is a sign the afterglow relay is going, or the glow plug relay. I personally don't think it's the GPR, but I figured I'd ask. I have a '91 f350 w\7.3. The glow plugs were are Beru, and 9 months old. thanks

 

[Jake S.]

87 up the controller is an all in one box, might be going bad. The relay itself is bolted to the top of the controller.

 

[quickster45]

can it be removed, or do you have to buy the whole glow unit? Never had to replace one yet. My third diesel, this is the first time this has happened. thanks for the reply.

 

[Jake S.]

Here's it at Napa: clicky

 

[Diesel JD]

You can replace the relay by itself and its a LOT cheaper than replacing the controller. A solid state controller almost never goes bad as a unit. I would place my money on a loose or dirty ground. Heck it's easy to service so I'd take it loose, clean the ground and clean the metal area it grounds too. How long does the "wait" lamp stay on?

 

[quickster45]

the wait to start light stays on 8 to 10 seconds when cold. I was thinking just to replace the relay. Going out to look for loose wires and such in a little bit. thanks

 

[Diesel JD]

I still think those symptoms describe a loose ground wire, the one from the controller that grounds to the motor in the stock location or to any good metal ground if it has been relocated. 8-10 seconds si exactly right for cold start. Good luck.

 

[Andylad13]

remember that it is supposed to click for around 20 seconds after startup depending on how cold it is.

 

[Diesel JD]

That's true, but I assume he means it continues to cycle even while its being driven. I'd say cycling for 30 seconds to a minute or more might be normal in very cold weather, but just cycling all the time or randomly coming on is not right.

 

[quickster45]

I was driving yesterday and looked down to see the voltage gauge going back and forth. 10 min. It works normally, 10 seconds when cold. But when the engine temp gets warm enough that the cold idle switches off, it starts to cycle. Has something to do with the afterglow relay.Thats built into the controller, so now I'm thinking I'll have to get a new one.

 

[Diesel JD]

The controller really doesn't go bad normally. I don't think the controller cares about that temperature switch. What it does is to turn on fast idle and advance the timing 2-3* when the coolant temp is <112*F. I bet you have bad connections or a bad ground. I guess buy a new controller if you want...it'll fix it if you properly hook it up and ground it, but they go for close to $100 and you can fix it yourself way cheaper. I'd not replace the controller until I'd convinced myself that the ground was good and ruled out loose connections and the relay as the problem. Why am I harping on the grounds...? Because they are very very important to not having that controller cycle after it should be off and other problems, but that is a common one which I've had to fix on my own truck. The ground was only a little dirty but when I cleaned it off real good it stopped doing the random cycling thing.

 

[quickster45]

I'm going to check that tomorrow. Believe me, I don't want to buy a new one if I don't have to. thanks for the input.I'll let you know how it goes.