GPR voltage drop??
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Hotshot
Joined: Oct 2003
Posts: 17,791
Likes: 98
From: Ashland City, TN
GPR voltage drop??
Anyone know the proper voltage drop when the GPR engages?
I'm getting a 7 volt draw right now, which is practically shutting the truck down, so no start. And I don't have a bypass wired in. Nor do I remember which wire is what anymore cause I put the damn stancore in like 13 years ago now.
I got a spare GPR thankfully, but again, don't remember which wire is what and goes where.
I really need to do the push button install.
Can't tell if I got a random UVCH problem, or GPR is just bad. I'm going to guess GPR, because its the most likely to fail age wise. Glow plugs are recent, and I did the SD uvch upgrade. So pin burnout chance is still there but really low.
I got the voltage drop running a meter on the battery and hard shorting the GPR and started seeing 5volts on the meter. Batteries are new this year too and connections are good.
I'm getting a 7 volt draw right now, which is practically shutting the truck down, so no start. And I don't have a bypass wired in. Nor do I remember which wire is what anymore cause I put the damn stancore in like 13 years ago now.
I got a spare GPR thankfully, but again, don't remember which wire is what and goes where.
I really need to do the push button install.
Can't tell if I got a random UVCH problem, or GPR is just bad. I'm going to guess GPR, because its the most likely to fail age wise. Glow plugs are recent, and I did the SD uvch upgrade. So pin burnout chance is still there but really low.
I got the voltage drop running a meter on the battery and hard shorting the GPR and started seeing 5volts on the meter. Batteries are new this year too and connections are good.
Got Data?
Joined: Dec 2012
Posts: 4,236
Likes: 1,368
From: Lake Stevens, WA
Ah you are welcome here - stop by often. Alot of OBS folks hang out in this sub, I think.
Got a picture of your GPR setup? Would like to look at your stancor installation. I did that on my last truck, and it was a good functioning unit.
Tell us exactly where you are measuring that 7 volt drop. There should be nearly the same voltage on both large posts of the GPR when energized - maybe 0.1V drop at most.
If your batteries are dropping 7 volts - enough to cause a no-start - I question your batteries, connections, or cables. Recommend taking a good look at each end - remove, clean and replace to confirm the connections.
Got a picture of your GPR setup? Would like to look at your stancor installation. I did that on my last truck, and it was a good functioning unit.
Tell us exactly where you are measuring that 7 volt drop. There should be nearly the same voltage on both large posts of the GPR when energized - maybe 0.1V drop at most.
If your batteries are dropping 7 volts - enough to cause a no-start - I question your batteries, connections, or cables. Recommend taking a good look at each end - remove, clean and replace to confirm the connections.
Cargo Master
Joined: Aug 2003
Posts: 2,332
Likes: 442
From: Eastern Washington
Yeah, what BWST said.
On cold days my voltage drops to 10.8v during the GP cycle.
7v is too low for the IDM to fire the injectors.
Oh, your IDI.... thats still super low.
I'd be checking all connections for resistance and voltage drop. If one terminal on one battery has a bad connection you'll get a huge drop like that, even with good batteries.
Also, resting battery voltage and condition.
If your GPR is engaging and causing the voltage to drop 7v (or to 7v) I doubt the GPR is bad. It's doing what it's supposed to, your supply voltage and/or connections are bad.
On cold days my voltage drops to 10.8v during the GP cycle.
7v is too low for the IDM to fire the injectors.
Oh, your IDI.... thats still super low.
I'd be checking all connections for resistance and voltage drop. If one terminal on one battery has a bad connection you'll get a huge drop like that, even with good batteries.
Also, resting battery voltage and condition.
If your GPR is engaging and causing the voltage to drop 7v (or to 7v) I doubt the GPR is bad. It's doing what it's supposed to, your supply voltage and/or connections are bad.
Logistics Pro
Joined: Mar 2007
Posts: 4,571
Likes: 836
From: knoxville, tn
IIRC the top wire is the trigger for the relay on the Stancor. I am with the others in that it shouldn’t drop that low. I would load test the batteries and check connections for corrosion or not being completely tight. Maybe also check the body grounds for corrosion.
the Stancor is not without the possibility of failure, but mine has been rockin along for about 14-15 years without complaint.
the Stancor is not without the possibility of failure, but mine has been rockin along for about 14-15 years without complaint.
Thread Starter
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Hotshot
Joined: Oct 2003
Posts: 17,791
Likes: 98
From: Ashland City, TN
IIRC the top wire is the trigger for the relay on the Stancor. I am with the others in that it shouldn’t drop that low. I would load test the batteries and check connections for corrosion or not being completely tight. Maybe also check the body grounds for corrosion.
the Stancor is not without the possibility of failure, but mine has been rockin along for about 14-15 years without complaint.
the Stancor is not without the possibility of failure, but mine has been rockin along for about 14-15 years without complaint.
I put the stancore on there... 12 or 13 years ago, never touched it, except with my arm working on the fuel bowl. fking ow.
I've started this truck for over a year with bad batteries in it through winters and never seen a voltage drop like this ever. And the batteries are only 7 months old.
And theys not the cheap ones.
Basically what I'm trying to tell everyone is that I'm passed the batteries part, did all that.
Thread Starter
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Hotshot
Joined: Oct 2003
Posts: 17,791
Likes: 98
From: Ashland City, TN
Yeah, what BWST said.
On cold days my voltage drops to 10.8v during the GP cycle.
7v is too low for the IDM to fire the injectors.
Oh, your IDI.... thats still super low.
I'd be checking all connections for resistance and voltage drop. If one terminal on one battery has a bad connection you'll get a huge drop like that, even with good batteries.
Also, resting battery voltage and condition.
If your GPR is engaging and causing the voltage to drop 7v (or to 7v) I doubt the GPR is bad. It's doing what it's supposed to, your supply voltage and/or connections are bad.
On cold days my voltage drops to 10.8v during the GP cycle.
7v is too low for the IDM to fire the injectors.
Oh, your IDI.... thats still super low.
I'd be checking all connections for resistance and voltage drop. If one terminal on one battery has a bad connection you'll get a huge drop like that, even with good batteries.
Also, resting battery voltage and condition.
If your GPR is engaging and causing the voltage to drop 7v (or to 7v) I doubt the GPR is bad. It's doing what it's supposed to, your supply voltage and/or connections are bad.
And yeah, when I manually short the GPR, I'm seeing a 7 volt drop on the batteries down to 5 volts.
But yeah, I'm used to seeing like 10.something on the GP cycle.
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Hotshot
Joined: Oct 2003
Posts: 17,791
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From: Ashland City, TN
Oh man, look at it all shiney and new.
Actually glad you asked for the photo,
I have a wire reference photo in this album from when I installed it also.
Only difference now is that it has 2 white nipples on it to keep you from zapping your arm on the dang thing and some dust.
For the 80 dollars I think they were, it was a worthwhile upgrade.
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Got Data?
Joined: Dec 2012
Posts: 4,236
Likes: 1,368
From: Lake Stevens, WA
You could check the glowplugs for their resistance, at least through the valve cover harness connectors - make sure one or more are not shorted. They should read 0.5 ohms by themselves, and a bit more with the intervening wire. Glowplugs usually fail to a resistance or go open though. Gotta trace out the wiring till you find the culprit, I think.
If you disconnect the GPR, what is the cranking voltage you see at the battery? Cranking RPM? Both of those good?
If you disconnect the GPR, what is the cranking voltage you see at the battery? Cranking RPM? Both of those good?
Thread Starter
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Hotshot
Joined: Oct 2003
Posts: 17,791
Likes: 98
From: Ashland City, TN
You could check the glowplugs for their resistance, at least through the valve cover harness connectors - make sure one or more are not shorted. They should read 0.5 ohms by themselves, and a bit more with the intervening wire. Glowplugs usually fail to a resistance or go open though. Gotta trace out the wiring till you find the culprit, I think.
If you disconnect the GPR, what is the cranking voltage you see at the battery? Cranking RPM? Both of those good?
If you disconnect the GPR, what is the cranking voltage you see at the battery? Cranking RPM? Both of those good?
But kind of fruitless. People suggesting things I already know and did, or was trying to avoid. haha.
Lead Driver
Joined: Aug 2022
Posts: 5,034
Likes: 1,406
From: Oologah, OK
the battery voltage is droping as much as you say, the batteries are bad, or severely discharged.
they should be at 13.3 volts when you try to start the truck,
put a Battery Tender on the truck, and keep the batteries at full charge,
then do your test.
12 volts is a DEAD battery, good only for Recycling.
my batteries sit at 13.3 and when the glow plugs are on, they drop to 12.1ish
when the starter kicks in, they drop to 10.9 at the lowest, usually 11.5ish.
depends on Temperature.
I have a DVM wired direct to the battery bank.
the starter pulls 800 amps for the first second
Each glow plug is pulling about 10 amps each times 8 if all are working properly. You are pulling about 80 amps.
that is NOT enough to drop the battery to 5 volts.
if there is a short, pulling enough current to drop healthy batteries to 5 volts, the wires would be melting.
get a Clamp ON ammeter and find out what the truth is.
if you were in Oklahoma, I would drive over and help you....
Diagnostics is my game.
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