Hello everyone. I got a 95 Ram 1500 5.9 V8 with a 46RH 4 speed transmission. I want to add an auxilary electric cooling fan and a bigger transmission oil cooler to keep the transmission cooler and extends its life. I live in AZ so it is hot. Before I do that I want to add a temp gauge to monitor transmission temp. I was going to just add a sensor through a T on the pressure line to the radiator but I was checking it out and it already has a sensor on the pressure line. Two wire plug to sensor has a ground and 5 volts when disconnected. So a standard 5 volt sensor. Through my research I found out that it uses this sensor to kick transmission into OD when warm enough and light up the "hot trans" signal on dash. I was wondering if I would be able to just T into the 5 volt wire (purple wire) and run that wire to my gauge so I don't have to cut the cooler line. I don't know what voltage range the aftermarket guages use as a signal wire. I would solder the wire in and then liquid tape it and run up to gauge. Do you see any problems with that? Mess up voltage reading back to ECU? Any inputs or suggestions? If I could take advantage of that sensor already there it would be great.

 

The five volts is the reference signal, the sensor then modifies that, and sends it back to the pcm to interpret. I don't know if there are any standards for such sensors...... none that I have ever heard of. So, using the existing sensor on an aftermarket gauge? Not sure you can make that work.

There ARE, however, clamps for the aftermarket sensor, the clamp the line, and the sensor, and the sensor reads temp by thermal conduction across the clamp. (clamp transfers heat from line to sensor.) They tend to read a bit low, but, it gives you at least some idea of trans temp, and doesn't require cutting the line.

Another option would be to plumb it in where the line already has a threaded break, up in front the engine, before the radiator. Of course, that wouldn't be super accurate either.... probably off by a few % one way or the other.....

 

Yeah. It was just a thought. Would be cool if it could be that easy. My understanding is that putting the sensor in the pressure line is the best way to measure transmission temp. Better than putting it on some test port. I was thinking of putting the T and sensor a little ahead of the starter before the harmonic balancer using a glowshift kit. Does that pressure line have alot of pressure? I see people use rubber hoses and clamps at the end of them connecting to radiator.

 

Not really. Consider that it comes from the trans, thru the cooler, and then just dumps back into the trans pan..... Pretty sure it's less than 20 PSI.

 

Okay. I am going to try that Glowshift T adapter for the sensor and hook that up to a gauge. I was wondering about the pressure because I have seen people just remove the factory hoses that you need special removal tools for and just install rubber hoses with clamps and add in line filters and bigger trans oil cooler and just use rubber hoses. Seems easier that way. Thanks for the suggestions.

 

Rather than hack up the line weld a bung on the pan.

 

Depends on your goal for the gauge, sump temp is about the least accurate way to monitor trans fluid temp, converter out is the most accurate of knowing what heat your fluids being subjected to, but sump temp is also an option, accuracy levels probably about the same as the other options listed above