Hello all, I'm new here as you can see. I recently put a new radio in my 94 Case 580SK, and the tach is now inoperable. I had to take the pillar post plastic off to get to the radio power wires and noticed that someone had just spliced them into the domelight wires. I unspliced the wires and ran new wires down to the fuseblock and plugged the hot wire into a spare location with a flate blade connector. The radio has an inline fuse of course. I had to pull the gauges out by about two to three inches so that I could get my hands behind them to run the new wires. The tach needle apears to have power going to it, it moves a bit when the key is turned on, but it is not responding to engine speed. Any help as to what I may haved messed up or which wires to check would be greatly appreciated. Thank you.
I forgot to add that the only other thing I've done to it is weld the muffler.
Your tack gets its signal from the alternator. See if it is charging. Check the wiring connectors at the rear of the instrument panel and also check the alternator bulb in the dash. If the alt light does light up with the key on and engine not running the alternator will not charge and the tach doesnt get a signal.
Thank you, I will check on that tomorrow and post the results.
If you have a light on and it is charging these machines were famous for bad wires from the "W" terminal on the alternator to the dash. You can test the output at the "W" terminal at the alternator. Start the machine and unplug the "W" wire should be yellow with a red stripe I believe. You should have 8 volts AC current at the terminal. If you have 8 volts just test continuity of wire to dash.
ALT light comes on then goes out when started. Volt gauge needle isn't quite where I would think it's supposed to be though, a little less than halfway. I haven't checked wires or probed around yet, rained all darned day and I don't have a tall enough building to shove this thing into, lol. Hopefully I'll be able to test things tomorrow.
Forgot one other thing. I put a fuse into the backup alarm slot(believe that's what it's labeled), started the machine and it screamed at me when I put it in reverse OR forward. That's about the same time that I noticed the tach not working(mostly because the loud beeeeeeeeeeeeep startled me into looking at the gauge cluster). All noise stopped when in neutral or when fuse was removed. I'm not sure if all of this is related or not.Just thought I'd enlighten you.
I think the other two terminals, on the 3-wire tach plug on my 580SK, are a 12V supply(with key on) and a ground. Phil