TC29D instrument panel

[wedwards]

I just bought a used TC29D and the tachometer, hour meter, fuel gauge and pto lights are not working. Does anyone have the expected voltages and resistance readings off the plug behind the instrument panel? I would like to find out if I am getting the right voltages before I drop over $600 for a new panel. Does anyone know where I could get a used one? I plan to take it out on the weekend and disassemble it to see if there is any loose connections. Any pointers on what to look for? The most annoying part was that the fuel gauge was working, but when I started it up it had quit tonight

 

[thclimer]

I'm sorry I don't know the specific answer to your question of voltage and resistance. I know Jinman has worked on his instrument panel in the past so maybe he can help. With as much as there is not working on yours it sounds like it could be something common to all, possibly a fuse or a loose wire/bad connection. I'm sure others here will try and help.

 

[justatractorguy]

While the idea that the fuel gauge was working while the other functions were not makes a fuse problem unlikely, the first thing that you might want to check would be the fuse for the instrument cluster. On the TC29D, that's in the panel under the hood on the firewall (on your left hand side as you look at the tractor from the front). The on the D, the instrument panel fuse is the second one from the top, but it might not be a bad idea to check all 5 while you're in there.

Next, you may want to check the ground connection. The grounds from the instrument panel and the fuel sender are all grounded at the left hand side of the engine block (the opposite side of the engine from the fuses).

 

[wedwards]

I pulled all the fuses and checked and cleaned them, as they all had a lot of corrosion on them. Got the fuel gauge working again and all the lights come on when the key is first turned. A definite improvement as I can live without a tach, but the way the fuel tank is laid out, there is no easy way to check the fuel level.

I noticed that the tachometer moves a little when the key is turned on, but doesn't go anywhere when the tractor starts, so it is getting power but no signal. When I engaged the pto and put the throttle wide open the pto lights didn't come on. Is it using the same signal as the tachometer? I am wondering if it is the rpm sensor that is bust. Does anyone know where the TC29D gets it rpm readings?

 

[cdcole]

I have a TC25D - basically the same tractor. I would isolate each piece by unplugging one item at a time, I would then plug each one in reseating each connector. I would look for blown fuses, broken cables, signs of wires that were accidentally crimped between the frame and bolts. Good luck this weekend and tell us what you found. Please.

 

[justatractorguy]

I noticed that the tachometer moves a little when the key is turned on, but doesn't go anywhere when the tractor starts, so it is getting power but no signal. When I engaged the pto and put the throttle wide open the pto lights didn't come on. Is it using the same signal as the tachometer? I am wondering if it is the rpm sensor that is bust. Does anyone know where the TC29D gets it rpm readings?

The signal current to the tachometer comes from the alternator. With all the corrosion you already had at the fuses, check and clean all the connections to the alternator and that engine block ground I mentioned. I think the ground is bolted to the side of the engine a couple inches below the starter.

 

[jinman]

As justatractorguy said, the tach input comes from the alternator. On my tractor, it's a pink wire. I'm not sure on the TC29D, but it could easily also be a pink wire.

The fuel gage is just a resistive gage. The float in the tank works a variable resistor which changes its resistance to ground. If you disconnect the wire going to the tank, you should be able to verify it is working by reading the resistance in the tank before and after fueling. If it changes, the float is probably okay.

It sounds like you are on the right track with all the cleaning and looking for bad grounds. I can't give you much specific info because my tractor is different, but it sounds like you are on the right track.

 

[wedwards]

I pulled the instrument cluster out of the machine and took it apart as far as I felt comfortable without a manual. It appears to be totally solid state, but I wiggled the tach to make sure it wasn't just unseated from a plug. Still no joy. I also checked the voltage from the only thing that seemed to be a sensor on the alternator (small plastic plug with two leads). At low idle it reads around .01 volts and at high idle about .35 volts. I don't know if that is the expected voltage (seems a bit low, but it might also be a pulsed signal). At this point I have ordered a electric hour meter from Princess Auto ($20) and will use it to keep track of hours for the maintenance interval. I am going to order the service manual and see if it has any diagnostic procedures. If anyone has any other suggestions, I am willing to try them.

 

[jinman]

I think what you may have read at the alternator is indeed pulsed. You might get a more accurate reading on the AC scale rather than DC. It also might be a fairly constant AC with varying pulse width or frequency that feeds the tach. The tach would then rectify that voltage and give a variable DC level to the meter circuit. . . or something like that.