Hi all, I've got a CAT 259b3 (serial number YYZ03203) with an hour meter that continues to run even with the key removed. Does anyone happen to have a wiring diagram? I've done some research, and it seems like it's going to be a wiring and/or alternator issue, but I haven't been able to find anything on this machine specifically. Thanks, Matt
How about a wiring schematic would that help? Might take some studying but should give you something to start with see attached file: There is a larger file with more information but I think I would need a email address to send it by Dropbox, if you want that send the email through the start a conversation method.
Thank you! I'll take a look and see if I can figure it out.
Is it actually running, as in clocking up time, or just staying lit?
It's actually clocking time. I can see it counting upwards with the machine off and the key removed. I was able to use the diagram @kshansen provided to trace one of the hour meter wires back to the alternator. I believe that is the signal wire which is telling the hour meter to keep counting. I'm planning to investigate further with a multimeter once the rain lets up. I read another post about a different machine with this same problem, and it turned out the alternator was bad. I'm not sure if that's the case with my machine or not.
After poking around the machine with a multimeter, I now have some additional information that hopefully someone smarter than me can use to point me in the right direction. At the hour meter: I unscrewed the hour meter and there are three wires connected to it. There's a red wire with 12 volts, a black ground wire, and a green wire that evidently goes to the alternator per the wiring diagram @kshansen provided. The green wire has 4 volts when the machine is off, and just over 7 volts when the machine is running. The hour meter stops counting when the green wire is unplugged. When the green wire is plugged back in, the hour meter doesn't start counting until the machine is started, then it counts and won't stop even when the machine is turned off. At the alternator: There's a connector on the back of the alternator with three wires, two yellow wires, and a green wire. I'm assuming the green wire is the green wire from the alternator. However, all three of these wires at the alternator have 12 volts when the machine is stopped, and 14 volts when the machine is running. I don't know enough about the machine to know if the voltages I'm getting are supposed to be what they are, or if there's something off. The 4 volts/7 volts at the hour meter seems odd to me. I'm wondering if there could be an issue with a relay or something between the hour meter and the alternator. Does anyone have any ideas as to what the issue could be?
I had some time to mess around with this some more. The hour meter is up to 6,000 hours now and there are only around 2,000 hours on the machine. I found this other post from a guy with a similar problem: HeavyEquipmentForums . His issue turned out to be the alternator. My alternator is charging the battery just fine -- I'm only having an issue with the hour meter. Would it be worth taking the alternator to a shop and having them test it? If I remove the wiring harness from the alternator, the hour meter stops. It starts counting again when the harness is plugged back in. This is with the machine off. I also determined that the hour meter will start counting when I apply 12v power to the green wire only (the signal wire). I'm wondering if there could be a short in the alternator and it is supplying current to the green wire even when the alternator is not running. Does that seem plausible?
Yes. Do this first. That's what the other guy did and it turned out that his alternator was bad. When you take it for testing tell them that you have 12v power on 403 Green at the alternator even with the engine stopped. That ought to give them and idea what to look for.
Please let us know how you make out! (I learn a lot from this site!)
I dropped the alternator at the shop. They said the bearings are bad for sure -- they could tell by spinning it. I'll let you know how it goes when I get it back.
If nothing else, put a cheap toggle switch on the green wire. You can flip it on to track hours for maintenance without it running constantly.
It was the alternator! Got it back from the shop, reinstalled it, and now the hour meter is functioning properly. I’ve got a new hour meter hooked to a 12v battery. In 3 months it will be up to 2,000 hours and I’ll swap it with the one in the machine.