I've searched the forums regarding the factory transmission gauge. Some say it barley ever moves, others say they have a normal temp around 160-180. The gauge in my 2006 C4500 with 1000RDS Allison didn't move off the bottom on a 400 mile unloaded trip. I checked power to the gauge, tested the gauge by grounding the input which provided full deflection. When I measured the sense wire to ground with cold tranny I got a reading of 6meg ohm. My question is what should the resistance of the sensor be cold and what is the "normal" temp range? I've also read two different locations for the sensor, in the valve body and at the cooler, which is correct?

Honestly my gauge will only move when loaded. I have a Bully Dog PMT so I can see the actual temp and in most cases unloaded I barely hit 150-160 deg. With my 15,000lbs trailer it will range 180-190 and on a really steep long climb out west in the summer its hit 200ish but only for a few mins so I doubt your gauge is broken. I thought the same thing for the longest time with mine.

I replaced my stock gauge with an autometer that starts at 100, empty I see 125, towing my trailer 140-160. 180 is the highest it has ever gone, I was going up a big hill on a hot day. So like you I thought my stock gauge was broken! Why did they put in a gauge that started at 170??????

I have had my trans up to 229 Degrees while towing.

I have had my trans up to 229 Degrees while towing.


What were you towing and where??

I have a ScanGaugeII on my Kodiak. It very seldom shows over 150 F. We have been traveling since Sunday in temperatures below 50 degrees. Which keeps these readings low.
The gauge on these trucks is controlled by the ECM. It does not read the actual temperature. Like the engine temperature which is run by the ECM there are dead spots in the meter readings. There is a good thread here on DP place that shows how the engine temp is displayed by TXchristopher.
I also have a external gauge that reads the trans temp. It is a direct reading and starts at 130 F. Very seldom reads in the current temperatures. As soon as temperatures get above 70 F the readings show on gauge.
Hope you did not damage your gauge shorting it out.

Thanks for the temp info, that eases my concerns and explains the odd resistance reading if the ECM is controlling the guage. I doubt shorting the gauge sense to ground would damage it. Every gauge I've messed with read in reference to ground that way only one wire is needed from the sensor, shorting the pin to ground just gives you full deflection to verify full range meter movement.

I replaced my stock gauge with an autometer that starts at 100, empty I see 125, towing my trailer 140-160. 180 is the highest it has ever gone, I was going up a big hill on a hot day. So like you I thought my stock gauge was broken! Why did they put in a gauge that started at 170??????

So did you mount a separate gauge? Where? Did you run a new sense line? Do you have photos of all this you care to share?

I got a topkick 4x4 gauge panel and mounted 4 gauges pyro,boost,trans and diff. I also installed a sender for engine oil temp and a switch so I can read it on diff gauge. flip the switch forward and read engine oil temp filp back and read diff temp. Look in garage for photos

I got a topkick 4x4 gauge panel and mounted 4 gauges pyro,boost,trans and diff. I also installed a sender for engine oil temp and a switch so I can read it on diff gauge. flip the switch forward and read engine oil temp filp back and read diff temp. Look in garage for photos

So the gauge panel was a stand GM (Chevy) part that you can get from the dealer? Are the gauges you used from GM also or did you buy after market guages? For the differental temp are you reading the front or rear? Why did you pick one over the other?

Yes the gauge panel is a GM part. The gauges are Autometer sport-comp. My truck is 2 wheel drive. With the diff temp gauge, I read rear diff temp, flip the switch, that I installed, I can read engine oil temp on the same gauge. If you look close at the pics I also made a alum. plate to hold the gauges flat, the plastic 4 hole panel is a little weak.

Very nice, neat job. Slick. I'm going to try this on mine. Quick question . . . where is the switch? I thought you might have put it in the set of switches below the gauges but I don't see it there.

I put it under the dash, it's a pain to get to the rocker switches. I did the switch weeks after installing the gauges.

Forgot to say thanks for comps!!

Not that I really doubted the advice from here. But you know how it is when something is new to you and just doesn't seem right. Well after having pulled with a load in warmer weather now and still not seeing my trans gauge move, I borrowed a contact certified temp probe from work, as soon as I got home I jumped under the truck, careful of the exhaust :eek:, and check the cooler line coming from the trans, 134 degrees, wow wouldn't not have thought that low. I was sure the dash gauge was wrong. I really wish they hadn't put such a high low end gauge in, for me I always wonder if it's still working. I'll probably still put a different gauge in or go with the scangauge system in the future.