Another cold start issue

Railroader_Joe · Aug 17, 2016

On a working gp system, it will show X amount of amps for 10 seconds or whatever.. I am getting voltage at the glow plugs with the key on, I have tested that.. but according to the scanner no amperage...... Mind blown

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TyCorr · Aug 17, 2016

Railroader_Joe said:
On a working gp system, it will show X amount of amps for 10 seconds or whatever.. I am getting voltage at the glow plugs with the key on, I have tested that.. but according to the scanner no amperage...... Mind blown

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Batteries load tested?

Railroader_Joe · Aug 17, 2016

TyCorr said:
Batteries load tested?

Not the new ones

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mikeeg02 · Aug 17, 2016

What are you using to show the glow plug amperage? Are you putting a shunt in line with the wire to glow plug relay?

Railroader_Joe · Aug 17, 2016

mikeeg02 said:
What are you using to show the glow plug amperage? Are you putting a shunt in line with the wire to glow plug relay?

I was using a scanner

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mikeeg02 · Aug 17, 2016

What kind of scanner? Except maybe a california model that I think has the solid state / digital GPR, there isn't anything on the hot wire to verify how much current the glow plugs are using. In order to do that, you would need to put an inline current shunt, or do it the less precise way with a DMM that has a current clamp. But they are typically not very accurate.

Even on the california model with the fancy GPR, I am uncertain if it has the capability to report current either.

Railroader_Joe · Aug 17, 2016

mikeeg02 said:
What kind of scanner? Except maybe a california model that I think has the solid state / digital GPR, there isn't anything on the hot wire to verify how much current the glow plugs are using. In order to do that, you would need to put an inline current shunt, or do it the less precise way with a DMM that has a current clamp. But they are typically not very accurate.

Even on the california model with the fancy GPR, I am uncertain if it has the capability to report current either.

I believe it was a snap on solus.. I was surprised as well that it was giving the reading in amps.. I assumed it would show voltage

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mikeeg02 · Aug 17, 2016

Well I wouldn't keep that part as useful information and carry on with your investigation.

What is the voltage across the two larger terminals on the GPR solenoid?
With the red probe on the one large terminal (B+ into the GPR) with the ground probe on the other large terminal on the solenoid (Wire that goes to the glow plugs) Polarity in this case with a DMM doesnt actually matter, just so you are going across the two large terminals with the DMM, and having someone turn the key on.

I know you said you replaced the GPR, but if the higher the voltage, the less power is getting into the glow plugs, and more is being "eaten up" (due to poor contacts) IN the GPR.

mikeeg02 · Aug 17, 2016

I can measure mine when I get home, but I put in one of these which is made to switch far higher current, and for a much longer time than what we seem to get out of the factory GPR's. I get them from digikey. The datasheet on them says the contacts are rated at 28 VDC (the lowest voltage they were tested at) and at 200 amps (make or break) should last in excess of 100,000 cycles.

It fits a little differently, but if you dont have an intake air heater I know it for sure fits in place. Wires may be hard to work with an AIH in place.

LEV200A4NAF

http://www.digikey.com/product-deta...nse-and-marine/LEV200A4NAF/A101171-ND/2362824

Railroader_Joe · Aug 17, 2016

IIRC it showed about 11.9 across the relay.. I can check again when I get home. Thanks for the link!!

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mikeeg02 · Aug 17, 2016

If you had your meter probes going across the relay, and you measured 11.9 volts. Your relay either isn't on, or is toast.

mikeeg02 · Aug 17, 2016

Remember, I want your black/negative/reference probe on one large terminal of the relay, and the positive/sense probe on the other large terminal.

Not in reference to ground or battery negative.

Railroader_Joe · Aug 17, 2016

So what should the voltage be across the two large terminals with the key on?

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lincolnlocker · Aug 17, 2016

with a digital volt meter take black probe and stick it to the negitive post on the battery. with key off the always hot side of the gpr will read the same as battery voltage so check the positive post on the battery and the always hot post on the gpr. should be very very close to the same number. now have someone turn key to the run position without startng the truck. if the truck is completely cold the relay should stay on for 2 minutes. within that 2 minutes check both large terminals on the gpr and make sure that there is not more than .25v (yes that is 1/4 of a volt) difference.. if there is more than .25v then the relay is no good..

live life full throttle

god bless america and the farmer who feeds your fat ass

Railroader_Joe · Aug 17, 2016

Ok... Just tested the relay. Battery showed 12.57.. Always hot terminal showed 12.57. THEN, when I touched both big terminals with the key still OFF, it showed 12.57.... Turned key to on, it dropped down to 0.3 volts

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lincolnlocker · Aug 17, 2016

Railroader_Joe said:
Ok... Just tested the relay. Battery showed 12.57.. Always hot terminal showed 12.57. THEN, when I touched both big terminals with the key still OFF, it showed 12.57.... Turned key to on, it dropped down to 0.3 volts

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swap the 2 small post wires around

live life full throttle

god bless america and the farmer who feeds your fat ass

lincolnlocker · Aug 17, 2016

wait? you touched the 2 big terminals at the same time? as in black probe on one and red prob on the other? or one at a time with the black prob on the negative post still?

live life full throttle

god bless america and the farmer who feeds your fat ass

mikeeg02 · Aug 17, 2016

Sorry I was away, yes, if you put your probe across the solenoid, it should only read less than .25 volts. I havent gotten home yet, been out helping my friends dad work on his dodge (shocker) Ill tell you what my relay does across it. (I cant remember)

mikeeg02 · Aug 17, 2016

Railroader_Joe said:
Ok... Just tested the relay. Battery showed 12.57.. Always hot terminal showed 12.57. THEN, when I touched both big terminals with the key still OFF, it showed 12.57.... Turned key to on, it dropped down to 0.3 volts

That relay could be better. It will show ~battery voltage with the key off. That means the relay is open. (Or failed) With the key on it should be .25 or less.

lincolnlocker · Aug 17, 2016

both posts will slowly drop voltage as the glow plugs draw it down so they wont match..

live life full throttle

god bless america and the farmer who feeds your fat ass