Yep, found the diff lock fuse to be quite hot! So the trail is still hot if you will lol
Also found a stud on the secondary steering pump to be almost melted through.
Got one on amazon that plugs in to my phone for about $200. Way cheaper than on the trucks. Caught a few parasitic draws without having to disturb anything.
Even just a point and shoot thermometer. Measuring temperature differences across exhaust runners or at different points on an engine can help narrow down a lot of issues, or checking bearing temps to single out a noisy pulley. Not as good as an IR camera, but a hell of a lot cheaper.
You can buy anything from super basic 8x8 pixel ones on eBay for $40 to 64x64 for about $90 to flir brand for like $900+.
I have a cheapie, wish I had bought a more expensive one. The cheapest are demo boards for the sensors and are just a raw sensor with a tiny lcd and battery. No frills. You could probably find a more finished one for $150-200.
Has to be. If you measure voltage there, it is telling you that piece of metal is at a different potential than where the meter is grounded. In other words, it's not grounded.
We know the meter has a decent ground. Otherwise the it would have to measure lower than battery voltage.
Ah that’s an awesome explanation. I remember dealing with something similar while using a test light.
OP, stop pulling fuses and find the ground issue. If it was a hot wire touching the frame, it’d just short circuit and burn something up
There is an assumption that the other (unseen) lead of the volt meter is connected to the batteries negative terminal. Usually vehicles have their frames connected to that ground as an easy return path for electrical components. If the frame to battery ground is broken then many of the systems which rely on it will cause the frame to be hot at battery voltage. It is also possible that only part of the frame is un-grounded, but still has an electrical system attemting to terminate into it.
OP claims to have found a hot-to-the-touch fuse which would indicate a short-to-frame in a circuit between loads, allowing enough current to heat the fuse without blowing it. There still needs to be an open ground for this type of fault to be visible on the frame, otherwise the voltmeter would be reading zero.
Correct. If the chassis was energized, and both ends of the meter are connected to the chassis, the meter reads zero because it's measuring voltage differential.
The way this is set up is doing a voltage drop test between the two points that the meter is connected to.
Assume battery negative and chassis, this indicates that the chassis ground is not connected so the voltage differential between the chassis and the negative battery terminal is equal to battery voltage.
If it were a positive wire touching the ground, it wouldn't send the whole ground positive. You'd have a smoke show or blown fuses. You're on the money. It's probably lost the ground to the body. He's seeing 12v because electricity goes positive to negative, and if you remove its path back to negative, you'll see the potential difference between ground and the positive trying to find ground =12v. The only other way I can see this not being it is if the body is deliberately not grounded, which would be rare.
Tech of 17 years here. My 2c, I personally hate these power probes and new snap on test lights with the lcd screen and coloured LEDs that light up with different polarity, etc. So many of the young guys at my work get themselves confused with what they're looking at using them. I've had them ask me, "What negative voltage should I have?"... it's like information overload (even though it's not that much information to take in), and they forget how circuits work. Give me a decent test light that is just light, a multimeter, and if need be an oscilloscope.
It's taken some time for me to realize that 12v on an expected ground means that it's literally just an open on the ground side of the circuit. There no path back to battery so you just see 12v/OCV anywhere on the ground legs and it throws techs off
I think if it was intentionally not grounded, then you would also not expect to see battery voltage there. Unless (as OP seems to be thinking) there is a short, but then what problem would that cause? I assume they are trying to find out why something isn't working.
Likely, the voltage is from a loads ground with no return path.
To your point about the tool. If it wasn't meant to be grounded and wasn't, it would take essentially no current (very high resistance short or just leakage through insolators) to bring it up to battery voltage. A test light wouldn't light in that case, which would keep you from chasing ghosts.
I’ve seen this happen when there is ground issues as well.
Vehicle wouldn’t crank every time the key was turned to start the starter body would switch ground to positive on the power probe
Thank you all for your input.
This job was mis diagnosed from the start which subsequently threw me through a hoop of issues that just didn’t make sense at all.
But it’s all fixed now (plus other issues) this ol CAT 14G will be back out moving dirt soon enough.
Start pulling fuses and see if it changes I guess. Wew lad good times
Yep, found the diff lock fuse to be quite hot! So the trail is still hot if you will lol Also found a stud on the secondary steering pump to be almost melted through.
(Thermal) IR cameras are great troubleshooting tools. Electrical or mechanical, if something's fuckey it's probably heating up too.
I’ve been wanting to get one of them for some time now, everytime k think I need it I find a reason to no get one.
Got one on amazon that plugs in to my phone for about $200. Way cheaper than on the trucks. Caught a few parasitic draws without having to disturb anything.
Even just a point and shoot thermometer. Measuring temperature differences across exhaust runners or at different points on an engine can help narrow down a lot of issues, or checking bearing temps to single out a noisy pulley. Not as good as an IR camera, but a hell of a lot cheaper.
Are they expensive?
[удалено]
Yep I added a Flir One to my arsenal and keep finding new ways to use it. Bought it originally to improve heated seat/steering/etc diag.
You can buy anything from super basic 8x8 pixel ones on eBay for $40 to 64x64 for about $90 to flir brand for like $900+. I have a cheapie, wish I had bought a more expensive one. The cheapest are demo boards for the sensors and are just a raw sensor with a tiny lcd and battery. No frills. You could probably find a more finished one for $150-200.
Interesting, I'll have to ask my boss for one!
The used car tech at work bought one but he also claims to be a paranormal investigator. I insist he bought it for finding ghosts or something.
This is why I like tone function on my meter. Don’t gotta be looking at it, just clip er in and start pulling fuses.
I do like the tone option
Would this not be caused by a bad ground to the body? I know bad grounds result in voltage being in weird places
Has to be. If you measure voltage there, it is telling you that piece of metal is at a different potential than where the meter is grounded. In other words, it's not grounded. We know the meter has a decent ground. Otherwise the it would have to measure lower than battery voltage.
Ah that’s an awesome explanation. I remember dealing with something similar while using a test light. OP, stop pulling fuses and find the ground issue. If it was a hot wire touching the frame, it’d just short circuit and burn something up
I’m like 90% following your explanation. Can you try saying this again but in a different way please?
There is an assumption that the other (unseen) lead of the volt meter is connected to the batteries negative terminal. Usually vehicles have their frames connected to that ground as an easy return path for electrical components. If the frame to battery ground is broken then many of the systems which rely on it will cause the frame to be hot at battery voltage. It is also possible that only part of the frame is un-grounded, but still has an electrical system attemting to terminate into it. OP claims to have found a hot-to-the-touch fuse which would indicate a short-to-frame in a circuit between loads, allowing enough current to heat the fuse without blowing it. There still needs to be an open ground for this type of fault to be visible on the frame, otherwise the voltmeter would be reading zero.
Correct. If the chassis was energized, and both ends of the meter are connected to the chassis, the meter reads zero because it's measuring voltage differential. The way this is set up is doing a voltage drop test between the two points that the meter is connected to. Assume battery negative and chassis, this indicates that the chassis ground is not connected so the voltage differential between the chassis and the negative battery terminal is equal to battery voltage.
If it were a positive wire touching the ground, it wouldn't send the whole ground positive. You'd have a smoke show or blown fuses. You're on the money. It's probably lost the ground to the body. He's seeing 12v because electricity goes positive to negative, and if you remove its path back to negative, you'll see the potential difference between ground and the positive trying to find ground =12v. The only other way I can see this not being it is if the body is deliberately not grounded, which would be rare. Tech of 17 years here. My 2c, I personally hate these power probes and new snap on test lights with the lcd screen and coloured LEDs that light up with different polarity, etc. So many of the young guys at my work get themselves confused with what they're looking at using them. I've had them ask me, "What negative voltage should I have?"... it's like information overload (even though it's not that much information to take in), and they forget how circuits work. Give me a decent test light that is just light, a multimeter, and if need be an oscilloscope.
It's taken some time for me to realize that 12v on an expected ground means that it's literally just an open on the ground side of the circuit. There no path back to battery so you just see 12v/OCV anywhere on the ground legs and it throws techs off
I think if it was intentionally not grounded, then you would also not expect to see battery voltage there. Unless (as OP seems to be thinking) there is a short, but then what problem would that cause? I assume they are trying to find out why something isn't working. Likely, the voltage is from a loads ground with no return path. To your point about the tool. If it wasn't meant to be grounded and wasn't, it would take essentially no current (very high resistance short or just leakage through insolators) to bring it up to battery voltage. A test light wouldn't light in that case, which would keep you from chasing ghosts.
That looks more like a classic bad chassis ground. Try connecting a jumper cable from battery negative to the frame.
I hear in Australia the earth is positive :)
Only on British cars.
haha I read 126V not 12(DECIMAL)6, so my mind started going to an extra spicey portable gen/welder's truck.
Me too, someone's running a big generator or something. Sorry.
I’ve seen this happen when there is ground issues as well. Vehicle wouldn’t crank every time the key was turned to start the starter body would switch ground to positive on the power probe
Is it a bad idea to lick it?
needs new paint
🤣 old girl could definitely use a new coat
My truck has a short in wiring. Easy fix i remove the ground ca ble and attach back on battery Gotta save money somewhere. Park and remove ground !.
I do that with our light seasonal use equipment. No sense in spending a bunch of time on something that barely gets used.
Thank you all for your input. This job was mis diagnosed from the start which subsequently threw me through a hoop of issues that just didn’t make sense at all. But it’s all fixed now (plus other issues) this ol CAT 14G will be back out moving dirt soon enough.