transmission Temp Guage Troubleshoot Help

[Giachino]

My transmission temp guage isnt working... . need opinions on what the next step is... . bought from Geno's... will call them tommorrow... .



Situation:



Guage has power (lights) and needle moves straight to 175 degrees... . wont budge from there no matter what... .



What I've done:



- Disconnect connector near pan... . guage powers, needle on 0

then tried

- Use small wire to "connect" both wires ..... needle remains at 0



Anything else I can test? Does this mean the sensor or box is bad? or does it lend to a wiring issue????Any thoughts?



Thanks, JG

 

[JApol]

I don't know the model you have but mine requires a power source other than what is needed for the lights.



Is yours the same and wired accordingly?

 

[Giachino]

Is yours the same and wired accordingly?

I believe so... . power to the box... and seperate power to the guage lights via the dimmer switch... .



JG

 

[McLaughlin]

I'm not 100% sure (don't have a wiring diagram available) but I think JApol is correct. The voltage goes through the gauge to the sensor in the transmission. As the sensor in the transmission gets hotter, the resistance changes and the needle moves higher on the gauge. Suggest checking the voltage at the input to the sensor when the transmission is cold. Truck not running but switch in on/position. I suspect you should have about 12 volts at the sensor input. If it isn't the same as what you are feeding the gauge then you may have a wiring problem between the gauge and the sensor. Next check the ground between the sensor output and the frame/battery it should be about 0 ohms. Finally, if both those checks are good, take that sensor or even another sensor (if you don't want to take out your current one attach it to the wire going to the gauge and drop the gauge in boiling/hot water after sensor gets hot connect the output/case to ground and your gauge should read approximately the water temperature.

 

[KevinO]

my plug ins on the back of the gauge grounded out to the bracket when i first installed it and caused a bad reading, you may want to check that too.

 

[Giachino]

Ok, went out today and checked the ground... no dice, caused the needle to stay at 0... . so was thinking / guessing and swapped the sensor wires (2 wires) and wala... it worked... . go figure... . guess the installers were a little on the sloppy side... . looks like the readings are approx 130 - 160 for normal driving... does that sound about right?



Thanks for the previous replys.