Temperature gage going/gone south

[GATC35]

Very timely post. My TC-45 did the same thing last week. Temp gauge will not move at all. Called the service manager at my friendly NH dealer and he said to jumper the wire at the sender to ground. Mine only went to about half scale deflection. So I guess I'll have to con them out of a indicator since my tractor is under warranty.

Mike...thanks for the pictures. Now I know how to get that rascal out of the panel.

Jim...thanks for starting this post. Answered many questions I needed answered this week.

mark

 

[Doc_Bob]

No, been doing it since I was a kid Bob.

You are still a "kid"
Bob

 

[jinman]

I fixed (replaced) my failing temperature gage last Saturday. It was a bit of a task to get the replacement gage. The first one arrived at my dealership in a box that looked like it had come from the landfill. To no surprise, the new gage inside was also crumpled. All my dealer could do was order me another one. Luckily, that showed up in about four days. $44 later, I had my new gage.

Before replacing the meter, I decided to follow the troubleshooting procedure in the Repair Manual to find out which test would show a faulty gage. I had determined the gage was bad by grounding the lead going to the temperature probe and seeing the gage only read half-scale. If you do this, the gage should go full-scale to the hot region.

I removed the instrument panel (photo 01) and then turned it over for the first resistance test. Test one (photo 02) was to check between pins 15 and 21 for 92-106 ohms. Mine tested at 98.6 ohms. The second check (photo 03) was between pins 15 and 24 for 203-237 ohms. Mine tested at 219 ohms. Everything looks good here. It's time to disassemble for more tests (photos 04,05, 06). You have to be careful when removing the gage if you don't want to bend the face. Severel tweeks with a screwdriver around the perimeter and the gage popped out of its socket.

 

[jinman]

Turning the gage over, I continued the tests (photo 07). Test three (photo 08) yielded 381 ohms, satisfactory. Finally, test four (photo 09) also yielded good results at 111.5 ohms. Everything about the old gage tests good, but it did not function properly. What's up with that? To be sure the new gage would have similar readings I did test three and four on it (photos 10, 11). I installed the gage carefully and re-assembled the instrument panel. Now the moment arrives where we'll find out if the gage works or I've wasted $44.

 

[jinman]

With the the instrument panel in the tractor and the ignition key off, I jumpered between the temperature probe and a convenient ground (photo 12). I turned on the key for just a couple of seconds and the gage read full scale. Success! (photo 13). I let the tractor warm up for about 10 minutes and my temperature gage read normal range (photo 14). So even though the old gage tested good, it was bad. To see how the old gage was made, I did further disassembly. Everything is buried in a coil of wire (photo 15). The only thing I can imagine that might be wrong is residue from condensation caused the meter needle to have more friction internally within the windings. Anyhow, I'm just happy my $44 wasn't wasted.

 

[PineRidge]

Glad you were able to get your gage working again Jim. 44 bucks sounds a lot better than the 300+ dollar cost for a new cluster.

 

[Soundguy]

I'll bet you are on the right track with the gauge error ( friction )

Years back when i worked at a water meter company, I built a calibration unit that read in the MA scale off a transmitter on a water meter head. You determined GPM of the meter based on MA on the meter scale.. In any case.. the first test units we made and sent out with the rep to atrade show had a meter with a needle.. The airport manhandled the unit and the needle would rub on the scale and not move well.

We did an emergency rework with a digital scale and all was well for the show.

Sounds like your (gauge) problem...

Soundguy

With the the instrument panel in the tractor and the ignition key off, I jumpered between the temperature probe and a convenient ground (photo 12). I turned on the key for just a couple of seconds and the gage read full scale. Success! (photo 13). I let the tractor warm up for about 10 minutes and my temperature gage read normal range (photo 14). So even though the old gage tested good, it was bad. To see how the old gage was made, I did further disassembly. Everything is buried in a coil of wire (photo 15). The only thing I can imagine that might be wrong is residue from condensation caused the meter needle to have more friction internally within the windings. Anyhow, I'm just happy my $44 wasn't wasted.

 

[klm]

Did you try removing and reinstalling the old gage? My guess is a bad connection on the plug-in, gage was ok??

 

[jinman]

Did you try removing and reinstalling the old gage? My guess is a bad connection on the plug-in, gage was ok??

I believe a bad connection is what the resistance checks would show up. Since they all read in a satisfactory range, the bad connection was eliminated. I did keep the old gage because I could apply some lube to the needle pin, but I have to be very careful with that since many lubes could also dissolve the wire's insulation varnish.

 

[TrippleT]

I have had this problem ad-infinitum. Replace the thing and in two months it is out again. I think the moisture has something to do with it. If you notice and I am sure you did, there are a lot of resistors, capacitors, diodes etc. So it may well be there are some things going on with those. I have replaced my gauge about three times and the instrument cluster once. NH should have a fix for this but I won't hold my breath. All I can say is that I have a very nice dealer that works with me. Seriously, I am thinking of just getting a weather resistant gauge set and mounting it where it can be seen, esthetics are out the door at this point for me. Other than this problem I love the tractor.