Glow plug controller failure

[shawn deere]

So my volt gauge has been flickering around. Didnt give it too much thought at first - factory gauges ya know. But could see the fuel pressure drop a bit when the volt gauge dropped. And the blower motor responded as well.

The problem seemed to be getting worse. Seems bumps set it off. And can manipulate it a bit with the throttle. Shook down starter wire thinkin it might be grounding somewhere. Couldnt replicate it. Thought alternator might be discharging randomly - 3g mod by the way. Or thought i could have done something wrong with the mod.

This morning it got bad. Smelled wires getting hot from the cab. Decided to do some more digging. Wire harmess plug on passenger fender looked freshly melted a bit. And them wires were hot.

So. Seems to me the glow plug comtroller was kicking in randomly. Anyone else have this happen? I ended up unhooking he power for the glow plug controller from the starter relay on the passenger fender for now. A new controller is $80 - $180

 

[pelky350]

My volt guage has been pulsing for months now and my lights react as well, new alt, new volt regulator, new belt. But my glow plugs are wired In manuallly now. Wiring harness has melted wire going into connector under hood to my engine harness, no idea what's going on in my electrical but have been running for years now on 3 switches lol fuel on, advance timing, and glow plugs. Lights work, fan works on own that's about it though lol

 

[franklin2]

The two yellow wires melting in the plug on the pass side near the A/C box is a common problem. Best thing to do is cut them out and wire around the plug, hopefully the smaller wires are still good going through the plug.

I have my glowplugs wired with a manual pushbutton also. Very easy to do, though some people do not like having to push and hold a button before starting their truck.

 

[pelky350]

The two yellow wires melting in the plug on the pass side near the A/C box is a common problem. Best thing to do is cut them out and wire around the plug, hopefully the smaller wires are still good going through the plug.

I have my glowplugs wired with a manual pushbutton also. Very easy to do, though some people do not like having to push and hold a button before starting their truck.

It was one of the little wires that melted on mine, if you touch the two ends together they arc and get hot instantly, something somewhere is shorted but truck drives fine without whatever shorted out lol

 

[snicklas]

Just to verify on the 7.3 Controllers, the white wire supplies a ground and this is what activates the relay, correct?

So a switch to ground from the post where the white wire goes, will activate the relay/glow plugs?

 

[gandalf]

I have had the pleasure of that melted connector. Four years ago my glow plugs quit, and I tracked it to the attached pictured connector. I rewired to the GPC.

You must be registered for see images attach

 

[shawn deere]

Mine looks like gandalfs! But why the heck would it cycle the glow plugs intermittently a half hour after starting when its 90 out?? Lol
Im thinking controller needs replaced or if anyone knows what tells the controller to turn on, id like to scope it out

Also that plug needs re wired...

 

[shawn deere]

The two yellow wires melting in the plug on the pass side near the A/C box is a common problem. Best thing to do is cut them out and wire around the plug, hopefully the smaller wires are still good going through the plug.

I have my glowplugs wired with a manual pushbutton also. Very easy to do, though some people do not like having to push and hold a button before starting their truck.

Im not opposed to a push button. But schooling everyone that would ever drive the pickup would be a pain. There are some relatively non gear headed people that get to drive it

 

[snicklas]

Mine looks like gandalfs! But why the heck would it cycle the glow plugs intermittently a half hour after starting when its 90 out?? Lol
Im thinking controller needs replaced or if anyone knows what tells the controller to turn on, id like to scope it out

Also that plug needs re wired...

The controller cycles every time it sees Key-On power. So, if the key on power is intermittent, it will cycle the plugs every time it gets power.....

 

[shawn deere]

The controller cycles every time it sees Key-On power. So, if the key on power is intermittent, it will cycle the plugs every time it gets power.....

That should result in a very short cycle if everything is hot though i would think. It was holding the glow plugs in way longer than i was comfortable with.

Ill still check out some wires when i get a chance on the controller

 

[franklin2]

I always have a rule, fix the obvious things that are broken first. There are a lot of little wires in that plug also, and it feeds everything on top of the engine. If you can I would try to keep some sort of disconnect plug in that location. If you ever want to pull the engine or change the valve cover gasket, it's handy to unplug those wires and get them out of the way while doing the work. Luckily the small wire section of my plug was still good, I only had to cut the yellow wires and then I used ring connectors and small bolts to bolt them together. I can then take them apart if I need to.

 

[mblaney]

Mine looks like gandalfs! But why the heck would it cycle the glow plugs intermittently a half hour after starting when its 90 out?? Lol
Im thinking controller needs replaced or if anyone knows what tells the controller to turn on, id like to scope it out

Also that plug needs re wired...

Your original description was the voltage gauge is flickering, so this does not necessarily mean your GP are cycling - it could be a short elsewhere. If your WTS light is cycling (with your voltage flickering) then something is cycling the GP controller (as snicklas said).

If you are replacing the GP relay consider an upgrade to a real one; see the link in my signature. The NAPA type relays are a POS and will only last a month. The White Rogers relay does fit, you have to put one bend in the shunt to line it up. One of the best mods I have done. Well maybe the D60 swap was a good one also.

 

[laserjock]

Check your connections for the key on (red) and ground. (Black). If either of them are loose and the unit looses power momentarily it will cycle. The WTS light should too if it's working correctly. My controller cycles the plugs longer than I think it should as well when it's warm. I will be putting a GP controller kill switch in. Hell mine is starting just fine on 7 plugs. I know it's on 7 because I found that #1 GP was disconnected last night. [emoji849]

 

[shawn deere]

Mine is starting ok with all the glow plugs disabled it just cranks a little longer in the morning

I disconnected the main power for the gpc for now. No more flickers or pulling way down the volts. Or burning wire smell.
I never did check the wts light, never crossed my mind. Found out what the deal was and unhooked as quick as i could, had to get moving along

Ill look into the white rodgers gpc. The one i got looks like a napa. And dont look that old.

I dont think anythingnis stock on my pickup any more anyways

 

[OLDBULL8]

If you do need a controller, PM me, got two left.