Technician requires some insight ( Energized frame w/ batts off )

[379Pete]

What kind of a response are you looking for, because obviously we aren't giving it to you? You want to debate whether or not current draw is an issue, because that's all there is left? The bigger question is why the attitude??

I’m trying to tell the original poster that what he is seeing is normal! That’s it. No question from me, it is a statement.

 

[Shimmy1]

Well, if I misunderstood your intent, I apologize, but you did lead off your post with three direct questions, and those were what kshansen and myself were addressing.

 

[Delmer]

His problem is that the LED warning light he added to warn the operator to shut off the disconnect won't shut off when the disconnect is off. Apparently the LED will shut off on other machines. THAT part of the problem I understand.

 

[Shimmy1]

An idea just occurred to me while going back and reading the entire thread. I hadn't posted anything other than a question about the $20 bill story because I don't comment unless I have something pertinent to add, but maybe this might be relevant? I read in an earlier post that the frame becomes positively energized. So, my question for the OP and others is the LED used on this machine identical to the others? If it is, then my thought is pointless. But, if it is a different LED, is it plausible that the one that stays lit is not polarity sensitive, and the others are? If the LED was polarity sensitive, it *shouldn't* light with a positive energized frame, because the ground wire coming from the frame is attached to the negative side. Maybe he can try an LED from a different machine to verify?

 

[379Pete]

Here’s my challenge, go disconnect the battery on your car or pickup and use a volt meter to measure the voltage between your frame and the negative battery terminal. All our vehicles are broken according to the original post.

 

[thepumpguysc]

I just read this LAST page so I'm jumpin in the middle/end of this..
Why not just leave the tester hooked up like that & start pullin fuses 1 @ a time & check the meter as u go??
Might as well start at the LED lite source as that seems to come into question..{good thinkin shimmy}

 

[Shimmy1]

Here’s my challenge, go disconnect the battery on your car or pickup and use a volt meter to measure the voltage between your frame and the negative battery terminal. All our vehicles are broken according to the original post.

You're overlooking something. On a normal vehicle, what you are demonstrating is perfectly normal, your DMM is taking the place of the negative cable. In the OP's situation, the master disconnect is switched off. Remove the positive cable as well and see if your meter shows voltage.

 

[379Pete]

You're overlooking something. On a normal vehicle, what you are demonstrating is perfectly normal, your DMM is taking the place of the negative cable. In the OP's situation, the master disconnect is switched off. Remove the positive cable as well and see if your meter shows voltage.

You’re wrong, Cat master switches break the ground only. I’ve been a Cat mechanic 26 years.

 

[379Pete]

 

[Shimmy1]

View attachment 190229 View attachment 190229 View attachment 190229

Yep, you're correct. I wasn't thinking when I posted that the positive always stays connected. So, I did a little digging, and discovered that my suggestion from an earlier post might be incorrect. I have thought in the past that some LED's are polarity specific, and some are not. From my searching today, i might be inclined to believe that is not the case. That being said, *if* LED's can only light with the correct polarity, if the OP's light is staying lit, he has to have voltage leaking around the master disconnect somehow.

 

[379Pete]

I didn’t pay a lot of attention to the LED part, so no comment. When he said having voltage potential between the frame and negative terminal I immediately knew the situation, and there is nothing abnormal about that condition. Not trying to be an A-hole.

 

[Welder Dave]

Does the machine in question have an ECM or other electronics? I'm the worst when it comes to electrical but have an odd issue with my new to me dump truck with a Cummins M11. It was a former plow truck and has 2 battery disconnects. One for 2 batteries and the other for the other battery(s). I run 3 batteries. I thought one of the battery disconnects was bad so I replaced it but the problem was still there so I only shut the one disconnect off. The other one when shut off causes one of the idiot lights on the dash to come on. I think I read somewhere that an ECM can store some voltage and thought that could be part of the problem. The idiot light stays off with the disconnect on. I can shut the 2 batteries off and the truck can sit for weeks and starts right up so I'm not worrying about the single battery being left on too much. There are stickers on the truck warning to disconnect both battery cables before doing any welding on the truck due to sensitive electronics(plow controls, GPS, etc.). Just wondering if there could be some electronic component storing energy?

 

[Theweldor]

Welder Dave
I have seen several times that when people installed master switches that they never picked up the wires for the ECM as they are connected directly to the battery posts. Just something to look at.

 

[379Pete]

Does the machine in question have an ECM? I'm the worst when it comes to electrical but have an odd issue with my new to me dump truck with a Cummins M11. It was a former plow truck and has 2 battery disconnects. One for 2 batteries and the other for the other battery(s). I run 3 batteries. I thought one of the battery disconnects was bad so I replaced it but the problem was still there so I only shut the one disconnect off. The other one when shut off causes one of the idiot lights on the dash to come on. I think I read somewhere that an ECM can store some voltage and thought that could be part of the problem. The idiot light stays off with the disconnect on. I can shut the 2 batteries off and the truck can sit for weeks and starts right up so I'm not worrying about the single battery being left on too much.

Yes sir, has 3 ECM’s. And yes they all have keep alive memory connections that are hot with the key off. And when you connect the last battery connection they make a big arc.

 

[Welder Dave]

Welder Dave
I have seen several times that when people installed master switches that they never picked up the wires for the ECM as they are connected directly to the battery posts. Just something to look at.

There were some smaller wires at the battery but they were cut off and not used. It has to be grounding somewhere other than at the battery connection. The truck is only set up for the dump box now and a lot of the electric cables were chopped off. I have 2 or 3 more solenoid operated hydraulic valves but the wires going to them were chopped off.

 

[TEX32]

Wow. This thread really blew up, while I was enjoying Christmas. Appreciate all the help and suggestions guys. I wish I could address all of the comments individually. ALL, and I mean all of your ideas and diagnostic practices have been attempted and thoroughly tested. Still the same issue. Same LED installed in all machines. Currently have 12 units wired with LED indicators. All work good. Another 980G sister machine was wired the same as well, without error.

 

[kshansen]

Another 980G sister machine was wired the same as well, without error.

May have already tried it but how about swapping the working LED from the one loader with the LED that is giving you fits from the other loader? Would not expect any change but at this point if it was me I'd be trying just about anything.

Or have you tried an incandescent lamp in place of the LED to see if that does the same? It can be hard to trouble shoot things from a distance and sorry if these suggestions have been asked and tried already.

 

[379Pete]

Ok, I re read the part about the LED. you want the LED dark with the master off, right? The only way to do that is to have the same voltage on both terminals of the LED, ie 0&0, 24&24 etc. it is normal to have the frame energized with the master off, I’m convinced of that. But if there is a small path to ground between the frame & negative battery post you will have a current flow through the LED & it will glow. Could be batteries that need cleaning or moisture in the master switch. I think you’re chasing your tail trying to figure out why the frame is energized. My2€

 

[kshansen]

And the thing with LED's is how low of a power source (or ground source) they need to "glow". That was why I was suggesting a good old incandescent bulb that would require a better source of power or ground.

This problem maybe just like the problems with gas engines with distributor, some of you might remember those things, you could get what was called "carbon tracking" the engine might run fine until the first damp morning then it would skip and backfire like crazy.

As this machine is run around a steel mill it could be something like that, but iron oxide dust some place, which I believe was the point Nige was making many posts back!

 

[Delmer]

And the thing with LED's is how low of a power source (or ground source) they need to "glow".

This reminded me of the first time I bought compact florescent bulbs years ago. I came home well after dark on a winter night at about 10-20 below zero, I was wearing a sweater and walked into my pitch dark unheated living quarters by feel and suddenly I could see from something glowing on me. I looked down and the light was gone, but when I walked the CFL bulbs in the packaging, in the bags would glow enough through the bag to be able to see clear enough to walk. I took the package out of the bag, rubbed it on my sweater and they glowed just like a glow stick.

LED's take half the power to make the light of florescents. And they like low voltage DC.