Glow plug problems

[icanfixall]

Look closely at the wire harness plug and those two yellow wires. They flow lots of power thru this tiny plug and it usually burns out from corrosion. Bypassing it with some 6 gauge speaker wire direct from the fender solenoid will fix that poorly designed plug. You can instal a circut breaker too if you want to. Caution..... In the oem harness this controller is always hot electrically. Just follow the wires from the solenoid lug to the controller... Its kinda scarey knowing its always hot..

 

[Jbevs]

I replaced the 2 main power wires with some heavy duty. No change. :rofllmao: Oddly enough, the z strip showed a small amount of power (less than 1 volt) while cranking. I think I am just going to install a push button.

 

[Agnem]

NO! STOP!

Ok geez... calm down Mel. Honestly, it's the internet. This is all imaginary....

OK, well I'm so tired of posting about this topic, and to see people sending folks off to other boards to get an answer is just, well... irritating.

Clearly I need to produce a full scale educational video on how to troubleshoot this system. It is so well designed, and easy to understand, really ANYONE should be able to figure out what the problem is.

http://www.oilburners.net/forums/showthread.php?27237-how-to-test-if-glow-plug-relay-is-working
http://www.oilburners.net/forums/showthread.php?27135-GP-s-or-Controller

What it really boils down to is this... The controller operates the contactor (also, called the solenoid or inappropriately, the "relay") Both can be bad, or if either one is bad, you've still got the same problem.

The CONTROLLER is in charge of how long the contactor is closed. It compares the volage going into the contactor (right from the battery) to the voltage leaving the contactor at the far end of the Z strip (which is a very low impedance resistor). If the difference is minimal, then the controller assumes the glow plugs are hot, and it opens the contactor, with periodic "checks" to monitor their temperature. On a cold engine, the voltage will be about half what the battery is. When it sees a 6 volt difference, it watches the glow plugs heat up, which causes that voltage to climb. When it gets to about 1 volt, it opens the contactor. If ANY glow plugs, wires, or connections are bad, the voltage will rise too quickly, and the system will fail to glow the plugs long enough to get them hot.

The CONTACTOR is nothing more than an on/off switch that provides battery power, streight to the glow plugs through the Z strip. If, when it closes, there is a high resistance connection due to contact pitting, internal resistance, or mechanical presure issues, then the controller will be misled into thinking the glow plugs are hot, and the contactor will open and click rapidly.

You can TEST the contactor very easily as I pointed out in the link. You can check the glow plugs easily with a test light. You can bypass the contactor just by shorting the two heavy lugs together with a metal object such as a screw driver to see if your truck will start on what few glow plugs you may have working.

 

[Jbevs]

It's clear I needed to search further to find the good explanations. Thanks Agnem. I will be testing my contactor today. All of my glowplugs test good. I think I will be shorting the contactor for a bit to get going fo now. Very helpful tip. Thank you.

 

[Jbevs]

Arcing the two big posts did not seem to help in starting. I was able to get voltage across the 2 large posts with the WTS light off. I have continuity between the gp wires terminal at the controller and the gp terminal at the gp's. When arcing the 2 large posts, I don't get voltage at the gp's I have no idea what that means. That is basically hooking the gp up directly, and I don't get any voltage. I did not think this issue would be that difficult.

 

[OLDBULL8]

Check the Black wire on the GP controller, it has to have a good clean engine grounding point.

Have someone turn the key on while you are under the hood to here if the relay clicks.
If it clicks then the controller is good.
If it don't click then the controller is bad.
Do you have battery voltage (12VDC) on the battery side of the relay?
If it clicks and stays on and you have no voltage on the Z strip, then the relay is bad.
If you have no battery voltage on the battery terminal, then the wire(s) coming to it are open (bad).
No voltage there then check the connector on the harness. These wires are fusible links, they can open "blow" just like a fuse. Don't try to check them by resistance (OHMS) unless both ends are disconnected.

Edit: Sorry Mel, didn't see your post.

 

[Jbevs]

It does click. I can hear it from in the cab. I checked the ground and it checked good with neg probe on the ground and pos probe on the pos battery. I will clean and check it again as well as pull all the wiring out from the plugs to the controller. The contactor is new.

 

[Jbevs]

I have power to the glow plugs! I have no idea what the problem was. BUT unfortunately I don't think that's the cause of my hard starting. Any other reason to blow a lot of white smoke? I think I'm going to put new injectors on to go with the new baby moose that's still waiting, new controller and harness and hope for the best.

 

[Jbevs]

These glow plugs really are tearing me up. Old controller was bad and actually started melting on the bottom. Never since I owned the truck have I had afterglow of the plugs.

I have new controller, new harness, and 8 new berus. 2 gp's were stuck, though not bad. However I still get the controller only flashing the WTS light then cycling the plugs.

I cleaned the main ground for the passenger side battery, cleaned the gp controller ground. I'm at a loss. What can I even look at? Why won't the controller act right?

 

[smolkin]

According to my Haynes manual, the duration of the afterglow is determined by the temperature at the controller itself. At 70F, it says,"3-5sec glow, 7-15 total" (4-10sec afterglow)... at 105F, it's "1-3sec glow, 3-5 total" (about 2sec afterglow)...at 140F, "1sec or less glow, 1-3sec total" (1-2sec afterglow). So at the summer temps right now, you shouldn't be seeing much afterglow. The smoking issues are probably not related...hope this helps.

 

[Blind Driver2]

how many volts are going to the GPs. A test light only indicates if there if voltage, not how much.

Is the engine idling smoothly while it's blowing white smoke?

 

[Jbevs]

I will check the voltage, but I don't think the plugs are getting any voltage now, except for the afterglow. It only blows smoke while trying to start, i.e. when cranking for up to 30 seconds at a time. When the engine is cold, like this morning at 60 degrees, the WTS light only flashed, then the plugs cycled for maybe 8 or 10 seconds.

 

[Jbevs]

I picked up a switch for manual glow plugs. I have the 7.3 controller. I use the switch to ground the post with the white wire, correct?