Temperature Gauge Issue

Finishing up a complete restoration of my ‘59. I just installed a new fuel and temp gauge in my ‘59. Both sending units are new as well. When I took it apart a year ago neither worked. The new gauges are Omix ordered from KW. The fuel gauge works fine. With the ignition off the temp gauge needle is just to the right of the “C”. When I turn the ignition on the needle pins to the left even further past the “C”. I have taken it apart 3 different times and made sure there was no contact with the post and the housing. Does the same thing with the sending unit wire off. Wiring harness is brand new from Walcks. Everything else works perfectly. What did I do wrong? Bad gauge? bad sending unit?

 

With ignition off, resistance at the sender terminal of the gauge to ground is around 23 ohms. It just doesn’t make sense that the needle goes the wrong way with ignition on. If there were a short would it go all the way to “H”? It’s doing just the opposite

 

This is from the '82 TSM, but it's the same as what your '59 has re this issue. You can see that the CVR ("constant" voltage regulator) is inside the fuel gauge. The connection A to S sends that regulated voltage to the temperature gauge via the connecting strap on the back of the gauges. It's made so you can't reverse the polarity when assembled. However, the temperature gauge has no internal ground. You can reverse polarity if you take the strap loose and connect the gauge backwards using a clip lead or such, ie A to A and S to the sending unit.

If you reverse the polarity and it works, then the part is defective and you can exchange it, or run with it wired backwards.

Is this a 6V system? If so, you may not have the CVR. The connections will be the same. Backwards polarity will make the needle deflect backwards.

 

I think the problem is the brand; Omix. Consider yourself lucky that the fuel gauge works. Out of 7 - 8 Omix gauges/senders I have worked with in the past 5 years, none have worked properly, if at all.
I try to find good used or NOS parts.
-Donny

 

Still have the old parts? If I did, I would put the old part in and see if it works.

 

Resolved! Thanks for your input. Yep, Omix does it again. Took the strap off and hooked the jumper to the “S” terminal and connected the wire from the sending unit to the “A” terminal. Works!

 

To Donny's point....just in case you're interested, here's a link to an NOS speedometer assembly on eBay. I bought mine from this same seller years ago. Unfortunately, these NOS speedos do not go cheaply.

This one would need to have the bezel repainted (shelf wear), but it looks good otherwise. If you get one like this, you would also want to clean out all the original grease and re-lube it with new white silicone grease.

https://www.ebay.com/itm/304475101554?fits=Make:Jeep&hash=item46e4215972:g:mXQAAOSw88Vds4Vv

 

Wow! That’s pricey. I have my original but unfortunately the speedo gear is seized. I had an extra aftermarket one that I’m using just to get on the road. Someday I’ll get to rebuilding the old one.

 

Im trying to learn about these things. I took mine apart to see whats up and they are burnt up i need new ones. People in the complaints about the omix ones say you need good grounds. But the original gauges are isolated from any ground. Also why does the fuel gauge have a set of points in it with second bimetalic strip. Is that a circuit breaker for them on the 12v in?

 

That should be the IVR or Instrument Voltage Regulator. In Timgr’s diagram above they are calling it the CVR or Constant Voltage Regulator.

 

ok I guess thats what brings it down to 5v. Also the shunt that connects them Iv read in the past that thats a resistor but now im not sure. And the new gauges do they wire up the same as the old ones with 12v coming in? According to the instructions they have no post for power

Wiring:
--Fuel Gauge:
S>Sender
I>Ground
A>Auxillary = this post jumps to the A>Auxillary on the Temperature Gauge
--Temperature Gague
S>Sender
A>Auxillary = this post jumps to the A>Auxillary on the Fuel Gauge

 

Good info thanks! I didnt see where it grounded but i will look at it closer. I bought new gauges they are not the old bi-metallic strip style anymore I guess omix updated them hopefully a little less sensitive and easy to use and repair. I found this amazon review helpful.
"If you have early model Jeep, that needs fuel and temp gauges, this is your best bet. These are not the bimetallic heat type meters, they are regular volt meter style movement. First off the ones I got, do not have the metal can, like picture shows. Once installed there is same chance for moisture etc, as original ones had but they are rugid build. Both meters use internal voltage regulator, with 120 ohm resistor, and 1N4735 Zener diode to ground, to supply 6.2 volt to meters, so don’t use the 5volt regulator strip from your original setup. Also both meters HAVE TO BE grounded, so make sure of that when installing them. That little brass screw on the back of both meters, is connected to Zener and the meter itself. Another biggie is that when engine is running and charging at 13.8 volt (or more), that Zener diode will be pushed to the 1 watt limit with the 115 ma or so coming through the 120 ohm resistor in the meter. I added on a buck converter to drop voltage to 12.0 volt, and supplied both meters with that. You could probably use a couple of regular 1N4001 diodes in series to knock off 1 1/2 volt from the power input from key switch. I’m sure they calibrated the meters for 12.0 volts, when they set them. The Omix-Ada 17218.02 temperature sensor works great with this temp meter, and my original gas tank sender hooked right up. As a note here, if your temperature or gas level changes, you can adjust the meter with a small screw driver. Look at the pictures and you’ll see the trimmer. There is a dab of silicone holding the preset, but it’s easy to remove. Clockwise will increase reading. I installed the new gauges, and before putting glass front back on I tested them, and they were just right, running off the Drok 12v regulator."

So I think im going to put in a TO220 12v regulator in the supply. Double check my senders for ground and ohms. Make sure the new gauge terminals are going where they need to go and grounds are good and that should get me in the ballpark if they arnt doa.