Glow plug controller questions.

[onetonjohn]

I've got an issue where when I turn the key on, I get clicking about 1 second apart for around 10 seconds. Putting a meter on the relay, I determined that the relay is on (current flows through) only while it's making the clicking sound. During the wait between clicks, it's off. I have 86 F350 that I've retro fitted with solid state controller. I was careful when I hooked it up, so I think everything is hooked up properly. Also, I think this was working properly a few months back. I read on the forum that this clicking will turn up if you have bad glow plugs. I ohmed them all out at .4 ohms. I think that means they are good. I'm suspecting the connector and will test them today, but realized I don't understand how the system works exactly.

Anyhow, I've got some pictures and questions.
The first one with the circled bit goes into a black wire that goes trough fusable link to the red wire (with arrow) in the last picture. What's the green barrel thing that connects the 3 wires? This is supposed to come on and stay on while key is on? I read the white wire controls the relay in the controller that allows power to flow from the yellow wires in the pic to the brown ones that connect to the glow plugs - and that can be connected to manual switch that grounds this wire to turn it on. Don't want to go there yet, but keeping it in my back pocket. Where do the two little wires on the relay come from? I'm familiar with relay with one control, but not sure how it works with two - unless key turns on one side while second side is grounded by controller, then controller pulls up second side to 12 volts when controller is cycled to turn relay off. That's probably it, but not sure.

Can a bad controller do this? Or can I limit my search to glow plugs and wiring (brown wires from controller to glow plugs). How does the controller detect there is a problem? Does it measure current supplied to brown wires?

 

[DaveBen]

It is my understanding that the controller uses resistance to determine if the circuit is good or not. An open part of the circuit (bad glow plug) will cause the controller to stop functioning. This is why we check every glow plug individually (about 1 ohm resistance) to make sure they all are working.

 

[onetonjohn]

It is my understanding that the controller uses resistance to determine if the circuit is good or not. An open part of the circuit (bad glow plug) will cause the controller to stop functioning. This is why we check every glow plug individually (about 1 ohm resistance) to make sure they all are working.

I checked every one in the truck from the bulb tip to engine ground. .4 ohms across the board.

 

[Rocknit4x4]

Not trying to add to your challenges but I had an issue a year or two back where I had partially failed fusible links - allowed voltage through (verified by multimeter) but during operations it wouldn’t allow full current flow. The controller did the same thing - clicking. I checked and changed all plugs (beru), replaced connectors, wires, controller / relay, all of it and didn’t suspect the power wires bc they measured good when hooked up. Eventually, decided to run a single 4 gauge from the starter solenoid and it solved my issues. Dissected the factory wires and the fusible links were toasted.

Might be worth running a temp power wire to confirm you don’t have a similar issue.

 

[ihc1470]

I would suggest checking the amp draw on the glow plugs. Total of 8 plugs will be around 200 amps. I have an induction amp meter so for me no big deal, for those who do not make your tester out of a 30-0-30 amp meter. Make the leads long enough that you can reach from a battery to the back cylinders. You do not need to remove glow plugs, go from battery positive to gp and measure the draw.

I got a set of China plugs marked Motorcraft one time. They drew 10 amps which the controller did not like. The problem trying to use an ohm meter is the resistance is so low to begin with most meters will not detect the difference

From your discription it does sound like you have some bad plugs.

 

[Nero]

Either bad plugs or bad power to the plugs in my experience. Usually a bad plug or two, or where the engine harness connects, the wires melt

 

[u2slow]

Ohm readings have not been reliable for me. They can have intermittent conductance, that breaks as soon as power is applied. Amp readings are more honest.

I also have no patience for these controllers. I revert to a basic solenoid and momentary pushbutton when there's any issues.

 

[IDIBRONCO]

I also have no patience for these controllers. I revert to a basic solenoid and momentary pushbutton when there's any issues.

Me too. Even though there's down sides to it, I feel that, overall a push button is the better way to go. Some people don't like them and I understand, but that's my opinion.

 

[onetonjohn]

I may have found something, but need better understanding of the operation. I have two blue wires out of the connector that are wired together via fusable links, and I don't think they should be. One of the blue wires goes to the red white strip wire that goes to top of glow plug controller. I think this should be hot when key is in the run position. The second blue wire is connected to the blue wire that comes out the back of the controller and has connector. I suspect these should NOT be tied together. Assuming that the red wire on top of controller should be hot when key is on, and that the blue wire on the back should go to the relay and will get hot after controller cycles effectively turning the relay off.

If this is true, I need to cut the wire that ties them together and connect the blue wires out of the connector to the correct locations. At least I should do this before continuing to debug further.

 

[Kdo58]

Checking glow plugs by resistance never worked for me, I pull them out and hook 12volts to each one to see if they turn red hot.

 

[franklin2]

I may have found something, but need better understanding of the operation. I have two blue wires out of the connector that are wired together via fusable links, and I don't think they should be. One of the blue wires goes to the red white strip wire that goes to top of glow plug controller. I think this should be hot when key is in the run position. The second blue wire is connected to the blue wire that comes out the back of the controller and has connector. I suspect these should NOT be tied together. Assuming that the red wire on top of controller should be hot when key is on, and that the blue wire on the back should go to the relay and will get hot after controller cycles effectively turning the relay off.

If this is true, I need to cut the wire that ties them together and connect the blue wires out of the connector to the correct locations. At least I should do this before continuing to debug further.

You said your truck's controller was a conversion in your first post. So more than likely none of your wiring colors are going to match the factory wiring colors for a truck that originally had that type of controller. Here are roughly the wiring colors and function for a truck that originally had this controller installed.

You must be registered for see images attach

glow plug controller

 

[franklin2]

Here's how it was wired in 1989. You can see the heavy duty power that supplies the glowplugs themselves has two fusible links, and two black/orange wires that turn into two yellow wires. If your truck was retro-fitted, someone may have used one large wire instead of these two wires.

The red/green wire is ignition on. This is the same red/green that feeds the injection pump, the cold start sensor and fast idle solenoid, and the brake vacuum switch. I think it feeds several other ignition on things on top of the engine.

You must be registered for see images attach

 

[DirtyWood]

Me too. Even though there's down sides to it, I feel that, overall a push button is the better way to go. Some people don't like them and I understand, but that's my opinion.

One major advantage of the push button is if/when there is a glow plug failure you can still glow the working plugs long enough to start the engine in cold temps. In my opinion the factory setup is great as long as everything is working properly, but on 30+ year old trucks "everything" is generally a bit beat or partially repaired. Just from looking at the connectors on my GP harness I can tell that when I next disconnect them I will need to crimp on new connectors as they have all nearly disintegrated down to just bare metal.

 

[onetonjohn]

Thank you. Looks like my wait to start signal is tied to my ignition on. That's not right. Do you guys have the wiring to the glow plug controller relay? Looks like I have 2 controls, 1 power input. And two outputs one thick one (that splits into two and goes to GPC power) and one other that goes? What are the two controls? One is key on. The other?

 

[Old Goat]

Thank you. Looks like my wait to start signal is tied to my ignition on. That's not right. Do you guys have the wiring to the glow plug controller relay? Looks like I have 2 controls, 1 power input. And two outputs one thick one (that splits into two and goes to GPC power) and one other that goes? What are the two controls? One is key on. The other?

In your 2nd picture in post#1, looks like you still have the GP Controller wired in on the R/F inner fender for the 83 - 86 GP wiring.
Maybe that is some of your problems? If you have them both wired in?


Goat