Railroader_Joe
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Another cold start issue
- Thread starter Railroader_Joe
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mikeeg02
New member
Thats why I asked the voltage drop across the relay.
Also, as the glow plugs warm up, the voltage drop will decrease, as the current consumption goes down some.
mikeeg02
New member
That is perfect and what we needed you to do.
lincolnlocker
Well-known member
dont do this then. lol
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god bless america and the farmer who feeds your fat ass
Railroader_Joe
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Ok just checked the not always on terminal to ground with key on and it showed 11.6 for about a minute then dropped to .01
That seems normal right?
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That seems normal right?
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lincolnlocker
Well-known member
did you hear a click right before it dropped to .01?
did both terminals read 11.6?
live life full throttle
god bless america and the farmer who feeds your fat ass
Railroader_Joe
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I heard a click.. I'll have to check again what the other terminal shows.. Now I can't remember
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Arisley
Moderator
OK, putting your meter probes on both big terminals at the same time will not show you anything.
Listen to Lincoln, he knows what he is talking about.
Sounds like you have either a weak relay, or really dirty relay connections.
Or weak batteries.
Or a combination of all of the above.
Listen to Lincoln, he knows what he is talking about.
Sounds like you have either a weak relay, or really dirty relay connections.
Or weak batteries.
Or a combination of all of the above.
Ok so what in the literal heck does a guy need to do?
Im only on my second relay but id like to test it before i just toss one in.
Check the negative batt voltage? Then the constant hot post on the relay?
Does anyone have a picture of the relay with the wires installed correctly? Thats gonna be the next problem. Wires in wrong spots.
Im only on my second relay but id like to test it before i just toss one in.
Check the negative batt voltage? Then the constant hot post on the relay?
Does anyone have a picture of the relay with the wires installed correctly? Thats gonna be the next problem. Wires in wrong spots.
lincolnlocker
Well-known member
read my how to post bud.. i got a autozone lifetime warranty gpr cuz at the time that is all i had available.. check it before every winter and replace.. i think im on my 3rd now.. lol
live life full throttle
god bless america and the farmer who feeds your fat ass
lincolnlocker
Well-known member
that means its operating correctly and shut off when you heard the click.. but still could be bad
live life full throttle
god bless america and the farmer who feeds your fat ass
mikeeg02
New member
Actually. Putting your Meter across on both big terminals is just as important as knowing your battery voltage during a glow plug cycle. That tells you the voltage drop across the relay. That tells you if the relay is making a solid connection or not.
You can check from battery - to each terminal during a cycle, but the battery voltage can and will change as the glow plug Cycle goes on, and the battery power gets used. And depending on how fast you are your readings may allow you to think your GPR is defective when it isn't.
lincolnlocker
Well-known member
so with key on, you put one probe on one big gpr terminal and the other probe on the other terminal, it will measure the difference? is that where the .3 volts that he found came from? and that is where it should read .25v or less?
live life full throttle
god bless america and the farmer who feeds your fat ass
mikeeg02
New member
Correct. As you and others have done, you can measure from battery - to each terminal, at which point if you write each down quickly and then do the math (depending on how many significant digits your meter has ) for example if you had 12.125 on one and you had 11.971 on the other yout would have .154 volts across them. Which (at least for me with short term memory issues) is hard to remember all the significant digits and do the math quickly. Now if you just put your meter probes on the two large terminals, you would measure the same .154 volts.
So when I check my GPR system, I measure the battery voltage during a glow plug cycle at the GPR, and then I measure the voltage across it.
If the drop across it is good, and battery voltage stays up and youre still unsure your glow plugs work, you need to check each wire to each glow plugs resistance to ground (which can be done at the valve cover gasket.)
So when I check my GPR system, I measure the battery voltage during a glow plug cycle at the GPR, and then I measure the voltage across it.
If the drop across it is good, and battery voltage stays up and youre still unsure your glow plugs work, you need to check each wire to each glow plugs resistance to ground (which can be done at the valve cover gasket.)
Last edited:
lincolnlocker
Well-known member
guess i didn't know that was possible.. never worked out to being the same numbers when i did it that way before.
live life full throttle
god bless america and the farmer who feeds your fat ass
live life full throttle
god bless america and the farmer who feeds your fat ass
mikeeg02
New member
I would dare to bet when you compared the two, going from the battery to the large terminals resulted in a higher voltage drop?
How this happens is as the glow plugs draw ~80 amps, your battery voltage drops, slowly but it does.
So when you check battery side of the GPR, lets say you measured 12.123 volts, had you checked the other terminal EXACTLY at the same time, lets say you would measure 12.000 volts. But maybe you had to put your meter down, write down the number and now your ready to check the glow plug side and you measure 11.987 volts. Now at this time the battery has discharged some and the other side of it is actually at 12.107. This change in battery voltage will change based on battery condition, glow plug condition, and how hot the glow plugs are, as their resistance will change as they get hot, and they will draw slightly less current.
Thats one reason why its more effective to just measure the drop across it.
How this happens is as the glow plugs draw ~80 amps, your battery voltage drops, slowly but it does.
So when you check battery side of the GPR, lets say you measured 12.123 volts, had you checked the other terminal EXACTLY at the same time, lets say you would measure 12.000 volts. But maybe you had to put your meter down, write down the number and now your ready to check the glow plug side and you measure 11.987 volts. Now at this time the battery has discharged some and the other side of it is actually at 12.107. This change in battery voltage will change based on battery condition, glow plug condition, and how hot the glow plugs are, as their resistance will change as they get hot, and they will draw slightly less current.
Thats one reason why its more effective to just measure the drop across it.
mikeeg02
New member
There is another contributing factor to different results with an OEM style GPR. If you do it over more than one key cycle, your results can vary widely. The OEM style GPR uses a rotating contactor. So every time you activate it, it rotates the contactor, ultimately giving you a new set of contacts. This works until they start getting arc damage and now there are "dead spots" or places that dont make good connection. So if it doesnt work the first time, it may work the second, or third.
I finally went out to my truck and cycled the glow plugs with my relay (which is an improvement over the old stancor 586-902, I have burned them up before using them to connect batteries together with large wire)
My voltage drop across the relay was initially .020 volts, and it settled at .017 volts. Measuring from terminal to terminal and quickly I had 11.55 and 11.53. The meter would round the .017 volts difference to .02 (because of the auto scale).
I finally went out to my truck and cycled the glow plugs with my relay (which is an improvement over the old stancor 586-902, I have burned them up before using them to connect batteries together with large wire)
My voltage drop across the relay was initially .020 volts, and it settled at .017 volts. Measuring from terminal to terminal and quickly I had 11.55 and 11.53. The meter would round the .017 volts difference to .02 (because of the auto scale).
lincolnlocker
Well-known member
i know how it works. i have a high dollar meter that is instantaneous when reading so i can bounce back and fourth between posts a couple times before it drops .10 volts...
live life full throttle
god bless america and the farmer who feeds your fat ass
mikeeg02
New member
My apologies, I didn't mean for that to sound like you were incapable. Just one of those little things that can get overlooked. In doing the battery - to contactor readings, I find myself going back and forth several times, as the battery voltage changes significantly while the fuel pump is running/ shutting down, ABS motor does its cycle etc. :thumbsup:
lincolnlocker
Well-known member
i understand bud. no worries. if both posts drop simultaneously then its easy to read. now if one is lazier then the other then there is an issue there too.. you covered that though with the contact points..My apologies, I didn't mean for that to sound like you were incapable. Just one of those little things that can get overlooked. In doing the battery - to contactor readings, I find myself going back and forth several times, as the battery voltage changes significantly while the fuel pump is running/ shutting down, ABS motor does its cycle etc.
live life full throttle
god bless america and the farmer who feeds your fat ass
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