Glow plug troubles

Big Bart

Tow&Slow
Joined
Dec 22, 2020
Posts
522
Reaction score
268
Location
Newport Beach, CA
In case you missed above, these guys make a quality one. Some others out there with generic wiring and connectors. But these are well done.

 

Jay Krout

Registered User
Joined
Jun 12, 2021
Posts
38
Reaction score
16
Location
Pitman PA
Before I spend the money for a harness I want test the glow plugs for resistance, this i dont understand how to do, i have a Dorman digital multitester I bought at Advance Auto cost about 39 bucks. Dont be too ******* me here, about the only thing I know about electricity is whats happenin at the end of that weld rod, I lookin for answers.

Do I need to take the plugs out to do this? Where do I put the test leads? There is 5 settings for ohms on this multitester...200, 2000, 20k, 200k, and 2000k...which one do I set it on. I dont know what they mean by resistance either.

Someone asked some questions what I did.

1 Yes i put antisieze on the threads, a diesel mechanic told me to, and dielectric grease on top of the plugs, that was my idea as a fix the other day.

2 No I didnt, I know nothing about ohms as I explained earlier in this post and asked questions about it

3 Yes I cleaned up all the connections

4 the controller and the relay were replaced together, they came out of the same box from Ford.

The continuity I checked the same way as when I checked, for voltage, lookin back now I shakin my head wonderin why I did that...if you got 12 volts and change you obviously got continuity...told you I wasnt an electrician.

2 or 3 years ago I made a harness for the glow plugs and it worked fine except for blowin up the controller every year, so I would just replace the controller and the relay all at the same time and that would fix it up.

As far as Classic Diesel Design goes, I know you folks like them. I had some dealings with them last year and it didnt go well at all. Nuff said about that I dont want to get into a ****** contest over it.

So I called Conestoga Diesel, they are in the middle of moving their busness to South Carolina.. The young lady I talked to told me they have them but they are in a storage facility and she will have to find them. It might take a week or 2 to get it, which is ok, I dont see winter happening for at least a month or so...Good Lord I hope so any way.

Thats just about evrything I can tell you about it. Thank you for your time and patience, I had some trouble with this computer and my daughter fixed it for me, thats what took so long to get back. I kept gettin booted offline for some reason. Sometimes I work a long 14 hour or so day and dont get on this thing. Any help you all can provide is appreciated.

Thank You
Popeye
 

IDIBRONCO

IDIBRONCO
Joined
Feb 5, 2010
Posts
8,151
Reaction score
6,540
Location
edmond, ks
I would set your meter on the lowest setting (200) to check the ohms. You don't need to pull the glow plugs out of your engine. Disconnect the wire from the top of the glow plug, touch one lead to the top of the glow plug, then touch the other lead to a clean ground on the engine. Sometimes it's hard to find a good, clean ground. You may have to clean up a spot. If you have your air cleaner off, which you should to gain access to the glow plugs, you can use the area that the bottom of the air cleaner sits (on top of the intake manifold) for your ground. You may still have to scratch the surface with your lead to get a good ground.
 

Jay Krout

Registered User
Joined
Jun 12, 2021
Posts
38
Reaction score
16
Location
Pitman PA
I forgot to ask...what for reading shoud I be getting for Ohms on the glow plugs?

Thank you

Popeye
 

Big Bart

Tow&Slow
Joined
Dec 22, 2020
Posts
522
Reaction score
268
Location
Newport Beach, CA
Jay,

Thank you for answering the questions. You did things right.

Now you mention you built your own glow plug wiring harness sometime back. That you think this is what is causing your controller to die each year. So it would make sense to replace them if your glow plugs check out.

Also check that the wires that bring power from the battery to the glow plug relay (Powers the glow plugs) are in good shape and bring very close to battery power to the relay.
 

Jay Krout

Registered User
Joined
Jun 12, 2021
Posts
38
Reaction score
16
Location
Pitman PA
I dont know if thats what causing the troubles with the controller or not, but evrybody here seems to think its the harness so I will take your word for it, you fellas know more about this electric stuff than I do. Maybe I messed somethin up doin the harness

The young lady from Conestoga told me they sell the whole harness, with all the other stuff, (the sensors, ignition wires and so on) thats on it as well. I think its 10 wires altogether goin into the big ugly plug. That might be part of the problem as well. If it aint to pricey I might just get the whole thing and replace it.

I dont know if I will get the chance to check the plugs this weekend or not, they got me bowed up like a rooster in a henhouse right now, and my daughters got somethin cooked up for Sunday bein Fathers Day.

Thank you
Popeye
 

TahoeTom

Supporting Member
Supporting Member
Joined
May 19, 2010
Posts
729
Reaction score
95
Location
S. Lake Tahoe, CA
You should check the plug between the controller and the GP harness. The two large wires are carrying the load and the connector is known to melt. I bypassed the plug and connected the wires directly.
 

chillman88

Supporting Member
Supporting Member
Joined
Feb 22, 2017
Posts
4,935
Reaction score
4,515
Location
Central NY
You should check the plug between the controller and the GP harness. The two large wires are carrying the load and the connector is known to melt. I bypassed the plug and connected the wires directly.
This is the best thing to do anyway.
 

ih8minimumwage

Full Access Member
Joined
Jun 29, 2011
Posts
155
Reaction score
66
Location
Coeur d'Alene, ID
If you just need to get 'er going and get back to work, even a temporary push button setup should help.

Disconnect the small + wire at the GP relay, run a wire from that terminal to a pushbutton, then an inline fuse, then to an adapter that plugs into an always "hot" spot in your fuse panel.
 

Jay Krout

Registered User
Joined
Jun 12, 2021
Posts
38
Reaction score
16
Location
Pitman PA
If you just need to get 'er going and get back to work, even a temporary push button setup should help.

Disconnect the small + wire at the GP relay, run a wire from that terminal to a pushbutton, then an inline fuse, then to an adapter that plugs into an always "hot" spot in your fuse panel.

I just keep the ol girl plugged in overnight, starts right up that way. If Im runnin the welder all day I plug it in to the welder. This week I been doin more cutting and fitting than welding, once I get a bunch of stuff tacked up I just weld for 3 or 4 days at a whack, plug it in then she fires right up
 

Jay Krout

Registered User
Joined
Jun 12, 2021
Posts
38
Reaction score
16
Location
Pitman PA
Ok I did the check on the glow plugs...all of them except 2 are at .5 ohms, the other 2 are .4 ohms...Im assuming this is good. I had the tester set on the lowest setting...200...i used the base of the air cleaner for ground. I geuss I did this right.

I cant do anymore on this today, I got a bunch of paperwork to do and my daughters have some kind of suprise for fathers day and this will most likely be an all day affair, so i have it plugged in for odark early tommorow morning. They busted a boom off a big Komatsu excavator and I have the pleasure to weld it back together...I love this work...seriously...I love the challenge...and...I understand this...unlike electrical crap on an old truck.

Next weekeknd I might tear into this harness if all goes well.

Thank you all for your time and help.

Popeye
 

IDIBRONCO

IDIBRONCO
Joined
Feb 5, 2010
Posts
8,151
Reaction score
6,540
Location
edmond, ks
.all of them except 2 are at .5 ohms, the other 2 are .4 ohms...Im assuming this is good.
It's been a long time, but it seems to me that the 6.9 and 7.3 glow plugs had different resistance ratings. I just took the ohms reading on one of my new ZD1-A's for a 6.9 and it read at .5 ohms. I think that the ZD9s for the 7.3s were supposed to be at 1.1-1.3 ohms. It seems like the 6.9 glow plugs were supposed to be at .5-.7 ohms. If I'm wrong, hopefully some one will correct me.
 

Big Bart

Tow&Slow
Joined
Dec 22, 2020
Posts
522
Reaction score
268
Location
Newport Beach, CA
Jay,

A slight variance of between .4 and .5 is ok. The test is to see if there is an open (No continuity) or a big variance like one tested .9. Keep in mind that the controller will work even if one is .9 or up to 3 are open. (Burned up.)

So now you will do a voltage test (DC on your meter.) to see if the power supply wires (As I recall there are two.) to the glow plug controller, are very close or the same as the battery voltage. (If they both have their own end connector take them off the gp controller/relay and test each one.) We are looking for voltage drop/resistance which means something on the supply side which is between the batteries and the gp controller has resistance and results in a drop in voltage at the gp controller post from that of the battery voltage. Usually due to a wiring issue or corrosion of a terminal end or a bad/loose connector on either the positive or negative side. When I say “from the batteries” the power for the truck systems (gp controller/relay) is actually taken from one of the big bolts on the starter relay. That bolt usually then has one wiring going to the battery. That is how it was factory on our trucks.

Now test each side of the glow plug harnesses for resistance like you did the glow plugs. Test at the 200 ohm setting. Unhook the harnesses at the gp relay and test each harness end, record the result for each harness. Now unplug The glow plugs. (If easy enough remove each harness out of the truck to bench test/inspect, if not leave it in and test.) Test at the 200 ohm setting each wiring harness from the gp controller end to each glow plug connector. Record the results. There should not be much variance between them, but a little due to each wire is a different length. My guess is where the 4 glow plug wires on each side tie/crimp together there is likely an issue with corrosion or burning that creates a resistance issue big enough the gp relay thinks there is an issue with multiple glow plugs and does not stay on. But it could be singular wire runs or their end connectors are causing an issue. Also if you have a factory harness on one side and a homemade one on the other, then likely they are not the same resistance and that can be adding to your issue. (Another reason to replace both with new ones.) Also keep in mind the controller is looking at the total resistance of both harnesses as it cannot see/sense/test the resistance at each glow plug.

So either the power coming to the controller is diminished or has voltage drop, or the controller is seeing a resistance total it does not like. Thus does a one second cycle and shuts off.

Also never assume a new part is working. There is a small chance the controller/relay is bad, more likely if it was not a Motorcraft one. But first let’s confirm it’s not a wiring issue. Something is killing your gp relay yearly, so something is not right, guessing you have a wiring issue that is causing your gp to die each year which is not common.

Like you did with the glow plug readings tell us what your findings are. There are only a few inputs to the gp controller and a hand full of wires it can be. We are all willing to help you go down the checklist and find the issue.

Happy Father’s Day Jay!
 

Forum statistics

Threads
88,147
Posts
1,077,304
Members
21,085
Latest member
Recmex

Members online

Top