Glow plug Diagnosing
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Glow plug Diagnosing
Hey guys been doing some reading on these glow plug system on the forum so if i missed something that would over obviously answer my question I apologize. My WTS light comes on for roughly 1 mayyyyybe 1,1/2 seconds i know thats way short, I also know that shortened WTS / glow time can be caused by a single or group of glow plugs failing. Are there any other causes? Ive read how to test, unfortuanately I must have a meter that falls into the "Cheap" class b/c it shows a dead short on a brand new zd9 and all 8 in my engine. I also did the pos batt term to glow plug terminal test and show a full 12.7 at all 8 which would be the same as a test light test, however I also noticed it was said you'll get a light/reading even if the plugs are not performing with in spec range. My question is, is it safe to assume my glow plugs need replacing if i have someone turn the key and test the power going to all 8, this should be fun as i have 1-1,1/2 sec to catch a 12v reading but what say you? Thankyou in advance, i intend to swap them out for International brand GP's as the dingaling before me used Autolites. Thanks folks
Post Fiend
Joined: Nov 2003
Posts: 21,285
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From: Nutter Fort, WV
Roadhammer92,
Welcome to FTE and the IDI diesel forum.
Look near your dip stick for the connector where the chassis harness connects to the engine harness.
One end of that connector has two larger wires, should be yellow or tan in color.
Does the connector look like it has been hot?
Will it come apart and if so is there any corrosion in the connectors for the larger wires?
Those are the power supply for the glow plug relay, so any problem there means not enough power is getting to the glow plugs.
PS, signature is not available till you have 26 posts.
Welcome to FTE and the IDI diesel forum.
Look near your dip stick for the connector where the chassis harness connects to the engine harness.
One end of that connector has two larger wires, should be yellow or tan in color.
Does the connector look like it has been hot?
Will it come apart and if so is there any corrosion in the connectors for the larger wires?
Those are the power supply for the glow plug relay, so any problem there means not enough power is getting to the glow plugs.
PS, signature is not available till you have 26 posts.
Postmaster
Joined: Apr 2009
Posts: 4,086
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From: Malahat/Cowichan Valley
yeah dave just got his signature, lucky guy! hahahaha. I am puttin money on either the controller(relay) or the connections to the relay. Like i said in other posts, mine was just a bit loose where the yellows hit the relay terminal on the controller and it caused all kinds of issues, specifically the starting lmao. If you have a test light that would probably be a better quick test for the GP's, never done me wrong. When i found my problem stated above, i had my son get in the truck and turn the key on for 10 seconds while i checked for power at the bullet connectors. I was reading near zero so i traced back from there and found the loose wires, just remember to be methodical.
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I am not finding a wireing harness of any kind near my dipstick. Any other location it might be on a 92?
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Post Fiend
Joined: Oct 2007
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From: Faibanks Ak.
Follow the wires back from your gp system to where there it goes to the main harness.
Sorry I'm not familar with the wiring on the 92 but that should lead you to the connector.
Sorry I'm not familar with the wiring on the 92 but that should lead you to the connector.
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ok yah it was kinda a quick check i was short on time today, but i definately did not see any wire harnesses of any type at all near my dipstick. Ill pull the aircleaner etc tommorrow and try to follow em from the solenoid behind the intake there, which im assumin is this GP controler relay dave was refering to in the one sticky w/ his illustrations.
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Welp I went for basics, I had someone turn the key while i used a multimeter and got the correct power which is like 9.6v going "to" the GPs for the 1,1/2 - 2 seconds my system is staying engaged for. I'm figuring this is enough to condemn the GPs, however I would like to know, If i take all of the bullet connectors simultaneously and retest will that allow the controller to engage power for the full 10-15 seconds? Or will this not even alow the system to enegize for lack of resistance/amp draw. Just thinking out loud here trying to diagnose and eliminate all other possibilites not that i know i have power going to the GPS. I'm not the parts changer type i like to find out why things arent working, what causes it and fix it properly, no band-aids here boys not on my daily driver. Thanks
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Freshman User
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didnt use a test light method, as i was told it is unreliable and not always a sure bet test. but im figuring if im getting the correct power to all 8 its gotta be the GP's. Scince essentially everything up to that point is working.
Cargo Master
Joined: Feb 2008
Posts: 3,409
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From: back in SE Iowa
correct but it is an easy way to tell if they dont light at all you know for sure they are bad.and my guess is you have a few that wont light it up.if it dont light its bad.its just a simple and easy test its the first thing i do when i troubleshoot glowplug issues
Post Fiend
Joined: Nov 2003
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From: Nutter Fort, WV
If you pull all of the connectors off the glowplugs, the relay will not close at all.
It needs a resistace feedback or it thinks all the glow plug are burnt out and will not turn them on.
You may see the wait to start light flash, but not even long enough for the bulb to illuminate completely.
Engine harness comes over the passenger side valve cover, should be near the dip stick and heads up toward the passenger side battery.
Not to be confused with the one going to the alternator from the passenger side battery though.
It needs a resistace feedback or it thinks all the glow plug are burnt out and will not turn them on.
You may see the wait to start light flash, but not even long enough for the bulb to illuminate completely.
Engine harness comes over the passenger side valve cover, should be near the dip stick and heads up toward the passenger side battery.
Not to be confused with the one going to the alternator from the passenger side battery though.