Faulty AT 545 Tranny Temp Sensor... HELP

[CVanDamme]

On our 92 TC2000FE our tranny temp guage quit working. Upon further inspection we noticed our wire came off of the sensor. Easy enough fix new end on the wire screw it back down, PRESTO. We then fire it up(engine and tranny both cold, been sitting for hours) the needle PEGS itself in the RED. No big deal sensor is shot, we drive to Tilbury get a new one, drop the fluid, change the screw on filter, replace sensor, top the tranny back up. Everything looks good - except I needed another 1/2 turn on the filter. Fire it up stays in the green, take it for a test drive it slowly comes up with the engine temp, staying 50 deg behind the enginge temp, probably 15 mins into the drive. Everything looks good, pats on our backs all around.
20 min into the drive I look down and its pegged again. Shut the bus off it stays pegged fire it up it stays pegged. Unplug it goes back where it should be. SOOO.... my conclusion is the tranny is NOT that hot, not possible to start boiling 20 mins in on a nice liesurely drive.
More things I noticed or thought of:
- Is there only one wire that goes to the sensor? The loom feels thick, almost like there is 2 wires in there? If so where would the other wire go?
- Would it be possible that the wire is grounding out, do I need to run a new wire?
- Is our gauge itself shot?

ANy and all ideas or help would be great.
Thanks in advance, Chris Van Damme

[frank-id]

The first task is to determine trans temp. Get a water temp gage that is a probe. Thread into a pipe threaded port on the trans. Or get a mechanical temp guage and connect into trans oil pan. Observe temps. If the trans temps are not high, the sender or wiring is bad. Get some 16 ga stranded wire to connect fron sender to factory gage. Check temp. Frank

[bus-bro]

Get an infared temp. gun and shoot the pan.

[paul iossi]

Once upon a time, they used to put a voltage regulator on the dash panels and run a lower voltage for instrumentation, if the regulator goes out the instruments read incorrectly, but that should affect the whole instrument cluster, not just one guage.
check actual temp with a known good guage and then determine where the problem is.

[CVanDamme]

Well we tore the dash apart and made a temperary jumper wire that we grounded out from the guage to the bus. And wouldn't you know the guage pegged itself. Then we ran a new wire to the sensor, and problem solved,.. so far.

Thanks for all the input everyone.

[dlor1]

So where is the temp sensor exactly? I have a trans temp gauge on the dash but just swapped the tranny and couldn't find a sensor. Would like to know temp though since I tow and live in the mountains.

[paul iossi]

the sender will be in the oil flow circuit and probably is in the case near where the cooler lines enter the trans, or the trans pan.