Glow Plug Relay test?
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Tuned
Joined: Nov 2013
Posts: 318
Likes: 7
Glow Plug Relay test?
Okay I put my multi meter on the GPR yesterday and I have 12.4 volts on the always hot side and 0 on the glow plug power side as it should. I turned the key to the on position and then tested both side. The always hot side went down to 11.2-11.4 and the glow plug side went to 10.8-11.1 volts.
Should I have 12 and 12 when the key is on or is the 11 volts on each side acceptable?
It was about 10 degrees outside yesterday and my truck did start without being plugged in, did seem to crank slow but I have 15w40 Rotella and it has been cold all week.
I tested glow plugs thru the harness on the passenger side and all 4 gave a reading of 1.2 to 2.0 ohms so those were all good. Didn't get to the drivers side because my fingers got cold and those plugs are a little harder to get to.
I am thinking my batteries might be a little week because after it said and idled for a good 15 min when I left and went down the road my battery light would come on and go off several times.
My only concern is that I am getting some white smoke on cold starts. Sorry for beating a dead horse with the glow plug and relay thread but I have been reading all that I find on here and just wanted to get some input.
Should I have 12 and 12 when the key is on or is the 11 volts on each side acceptable?
It was about 10 degrees outside yesterday and my truck did start without being plugged in, did seem to crank slow but I have 15w40 Rotella and it has been cold all week.
I tested glow plugs thru the harness on the passenger side and all 4 gave a reading of 1.2 to 2.0 ohms so those were all good. Didn't get to the drivers side because my fingers got cold and those plugs are a little harder to get to.
I am thinking my batteries might be a little week because after it said and idled for a good 15 min when I left and went down the road my battery light would come on and go off several times.
My only concern is that I am getting some white smoke on cold starts. Sorry for beating a dead horse with the glow plug and relay thread but I have been reading all that I find on here and just wanted to get some input.
Post Fiend
Joined: Dec 2010
Posts: 10,121
Likes: 3
From: Orrville, Ohio
It sounds to me like your GPR is fine, but your batteries may be getting a little weak, though at that temperature those readings don't seem terrible to me.
Some white smoke on startup is to be expected when it's that cold. A little puff and then a light haze is one thing, but if it is fogging out the neighbors, then you may need to look a little farther.
The GP's should test out to be around 1 ohm each. It sounds like you may have a few that are testing as being a little weak, which may be contributing to the smoke you're seeing.
Some white smoke on startup is to be expected when it's that cold. A little puff and then a light haze is one thing, but if it is fogging out the neighbors, then you may need to look a little farther.
The GP's should test out to be around 1 ohm each. It sounds like you may have a few that are testing as being a little weak, which may be contributing to the smoke you're seeing.
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Tuned
Joined: Nov 2013
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Thanks guys that is what my suspicions were but wanted to get some input. I just bought the truck in November so I am trying to go through and make sure everything is up to par. I would like to replace the glow plugs as I have no idea what the previous owner installed. I only use ZD-11's so I don't what to have a auto(no)lite issue with them swelling up if that is what someone else installed.
The batteries are DieHards but I haven't been able to find a date on them. I am guessing they are getting up there in age as the truck is a 96 with only 130,000 miles and I believe the previous owner only towed a camper with the truck so it was not a daily driver.
I will get the batteries tested and for sure change the glow plugs once it warms up a little.
It smokes after start up but I wouldn't say it is a fogging but seems to be more than a just a haze to me, so I think with the batteries being a little weak and a few glow plugs possibly being week or failing that is what I am getting.
The batteries are DieHards but I haven't been able to find a date on them. I am guessing they are getting up there in age as the truck is a 96 with only 130,000 miles and I believe the previous owner only towed a camper with the truck so it was not a daily driver.
I will get the batteries tested and for sure change the glow plugs once it warms up a little.
It smokes after start up but I wouldn't say it is a fogging but seems to be more than a just a haze to me, so I think with the batteries being a little weak and a few glow plugs possibly being week or failing that is what I am getting.
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
Drop limit is 0.3V, NOT .03. Still, that puts you RIGHT at that margin. Combine that with the marginal battery strength and yeah, you're gonna have smoke.
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Elder User
Joined: Jan 2012
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From: Southern West Virginia
If you do end up replacing the relay, I would recommend getting a Western Plow Relay Deprecated Browser Error
They are much cheaper than other aftermarket relays, like Stancor, and even cheaper than an OEM replacement, and they are much beefier. They don't mount exactly like the OEM relays - both mounting holes don't line up, so you can only get one bolt to hold it on, but I think they are better. I've had one on mine for close to a year or so now, and it has done well. I also ordered one to put on my dump trailer, which quickly burnt up a cheaper relay. This one has been holding strong.
They are much cheaper than other aftermarket relays, like Stancor, and even cheaper than an OEM replacement, and they are much beefier. They don't mount exactly like the OEM relays - both mounting holes don't line up, so you can only get one bolt to hold it on, but I think they are better. I've had one on mine for close to a year or so now, and it has done well. I also ordered one to put on my dump trailer, which quickly burnt up a cheaper relay. This one has been holding strong.
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Elder User
Joined: Jan 2012
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From: Southern West Virginia
I just noticed in that link that the picture shows it mounting on it's side...that's not the way mine came, so I'm not sure if they changed them or if that picture is not of the actual relay. The one I ordered, which is part # 56131K, has the mounting plate on the bottom so it sits just like the OEM GPR. They also increased the price a little from when I ordered mine. I think mine was something like $21 including shipping. I'd go ahead and get one to have if I were you. Or go ahead and replace it before it does go out. That's cheap.
Hotshot
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From: Southern West Virginia
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