Recently purchased a 2004 Cat 257b. Been cleaning it, getting fluids and filters changed and repairing some small things. Cannot figure out why the horn does not work. The backup alarm works fine. The fuse checks good and have 12V coming to it. The horn button checks ok also and has low voltage about 2V coming to it. Tried to follow the wires to find the horn relay but cannot see where they go. Does anyone know where the horn relay might be or have an idea of what else might be causing the horn to not work? Thanks
I have never worked on this machine, but it does not seem right that 2 volts should trigger the horn relay. As opposed to ac, dc voltage does not lend itself well to changing. Hence, I don't think a manufacturer would go to this trouble. Most likely the horn switch needs 12 volts to it.I would trace back that low voltage, look for bad grounds, corrosion on fuses, connectors, etc.
Horn fuse should be sending 12 volts to the horn button on the left control through wire # 114 that should be #3 in plug for left control. Power fron horn button would be to terminal/socket #2 and go to the horn via wire number 322. Black wire # 200 on horn should be the ground. If you only have 2 volts getting to the horn button there must be a problem in the fuse or wire from fuse to the left control. Unless I'm missing it in the schematic there is no horn relay. If you can send me a private message with an email I could send you the wiring diagram, it's a 1.76 MB PDF file
KSH, he can't PM with only 1 post. I already emailed the OP offering him the schematic.
Ok, I'll have to look some more at the wiring and fuse box. Hard to trace where the wires are going the way they are bundled up and routed under things. Good to know there is no relay so I can quit looking for that. Hopefully I can get access to the schematic. Thanks
Just checked my inbox and found your mail - schematic is on its way.
Well then I can delete the copy I had saved for YoungCy. If he only has 2 volts getting to the horn button I'd suspect a bad wire or plug connection in the wiring from the fuse to the button. I know with my luck if I started checking the wiring starting at the horn button I would find the problem was a corroded contact in the fuse holder:Banghead
Thanks for the schematic. Think I'll start at the fuse box cause the horn button and connection below the joystick looked good. But will have to wait a few days as the weather finally turned dry here so have to get some hay put up. Will let you know what I find out. Thanks for your help.
Horn works now. The wire from the fuse to the horn button was broken. Ran a new wire and the horn works fine. Thanks for everyone's help.