i installed my trans. temp gauge yesterday, but instead of mounting a new temp. sender, i just spliced into the factory trans temp. sender wire that goes to the ECU. it does seem to work, but i don't know what temp. reading i should be getting. it came up to about 110 deg., but that was after driving for only 5-10 miles. seems to me it should come up to approx. the same temp as the coolant, as they are plumbed together through the radiator. is this right? maybe i should stop being so lazy and intall the new sender? if this trick (splicing into factor sender wire) actually works, why wouldn't everyone do it? it only took about five minutes.

 

They do not do it that way because you really want to see what the temps are instead of what the chip is programmed to tell you. I learned a long time ago NOT to trust computers too much!

 

nah, i spliced before the ECU. from the wire that comes directly from the transmission

 

oh yeah, i don't trust computers either, thats why my truck is a 12-valve.

 

Been there done that, it doesn't give you correct readings to run two "gauges" off one sender.
You will have to cut the wires completely and splice in a 1000 ohm resistor across the wires to the PCM to get a good reading.
The resistor tricks the PCM into thinking the fluid is warmed up, otherwise OD won't engage.

 

i don't know about the accuracy of the reading, but overdrive seems to work fine.

 

That's because your stock gauge is still hooked up. Problem is it's making the aftermarket gauge read low.

 

so a 1000 ohm resistor will fix this? how do i do this? solder the resistor over the splice?