I know this has been beat to death but even after searching I've been unable to find the two pieces of information that I need.

1. What size NPT is the factory temp sender in the hot line going to the heat exchanger.

2. If I wanted to disable the factory sender with a resistor. What value resistor would I use. I've read both 7.5Kohm and 100ohm.

So far I have tried the sender in the pan and the second test port on the passengers side. The pan yielded hotter temps on average which also fluctuated more than the 2nd test port. So I'm either going to "T" in at the factory sender so both the OE sender and my autometer temp sender can be used or just simply disable the OE unit in favor of of the AM gauge.

 

1. What size NPT is the factory temp sender in the hot line going to the heat exchanger. It's 3/8''

2. If I wanted to disable the factory sender with a resistor. What value resistor would I use. I've read both 7.5Kohm and 100ohm.
You need to use a 750 or 1k (1000) ohm, 25¢/ea at Radio Shack.

It doesn't work to use a tee at the factory sender port, been there done that. With the factory sender out of the fluid flow it takes 20 miles for the sender to read high enough to allow OD. Jumping the factory sender wires with a resistor solves that.

 

What Bill said

 

so is it best to put the temp sender on the factory spot or that second test port.thanx

 

Not all senders will fit in the 2nd test port. Rather than find out yours doesn't while fluid continues to come just use the port for the stock sender in the output line. It always works.
I also like it better with the stock sender tricked with a resistor, you can go into OD right away when it's cold out. Several tranny experts have assured me it's ok to lock up with cold fluid.

 

Sounds good to me Bill ,Ill do it that way.do you just put each end of the resistor in the plug of the stock one.I havent gotten down there to look at it yet.My trans temp gauge is on the way.

 

The stock sensor can go in your toolbox, just jump across the two wires to the PCM. I prefer to solder and heat shrink the resistor into the wires with the connector cut off. I bend one resistor lead back on itself to make a compact inline unit.
One fellow who I installed a sender for in the stock location wanted to keep everything stock intact so what I did was bend each resistor lead back on itself to make them double thickness then push the resistor leads into the end of the connectors to the pcm, they fit tight, then electrical taped it. Stock sender also in the toolbox. He hasn't said anything in two years about it not working and knowing him as I do he definitely would.

 

I followed Bill's advise and application to the "Tee" and he is perfectly correct. No problems, just one, the 1 ohm resistor I could not buy as an individual at our local "Radio Shack" had to buy a pack of four at $1.00 a pack. So now I have an extra three.----Great info. Bill Thanks again --Ray

 

WILL THIS WORK ON A 97? AND IF SO, CAN YOU BE A LITTLE MORE SPECIFIC ON THE PROCEDURE? - sorry for yelling!

 

Doodah: From what I have been told by Infidel the location of the sensor{sending unit} is on the cooling tube on the 1995's Autos only. I believe you can get an aftermarket tube to replace the stock cooling tube other than 95's. Maybe someone else will chime in and help me out.-----Ray

 

Ray is correct, the outlet tube was only used on the RH tranny from '94 to early '96. On the later RE trans the stock sender is internal to the tranny. You have to buy an outlet tube for a earlier model for your '97, about $95. You don't need to mess with the stock sender though.

 

I have my gauge sender in the stock tee in the tranny line wherte the dummy sensor goes. My gauge never reads more than 100 degrees..... I've felt the lines & tranny pan, & its sure been over 100 deg. Any thoughts?? Where is the HOT line on a '94 rh47???

 

I'am only familiar with the 95 it is one of a kind when it comes to the location of the sender. As for a 94 I am sure Infidel will help you out. He seems to know alot on the early model Ram Diesels.

 

Hot line is the only one you can hook up to easily, has the stock sender.

Mine rarely reads over 120F unless I'm driving under 30 mph for long distances.
Many people never see this because their gauges start at 180° or 140°.

If you go into OD lockup right away after starting up the tranny temp can stay quite low as no heat is generated when the TC is locked up.
Try driving slow with the A/C on and my bet is you'll see higher than 100.

 

Bringing this old thread back- this summer I replaced the steel leaky lines with high pressure hose, zip tied that temp sensor to a close bracket....didn't think about it since- TODAY, when it was 36F and I jumped in my rarely driven 12v to head across the mountain- and my oh my is 3rd gear terrible, sat at 50mph until the thing finally allowed OD after a hour or so. So, 1k resistor- sounds simple but sprint bought out radio shack, auto parts store clerks look at me like I'm nuts- amazon has them but they look very weak- is there a waterproof one I should get, or just by the crappy one on amazon and dip it in plasti dip or something?