Engine/Transmission (1994 - 1998) Trans temp sender

[BDech]

I am having problems with my trans shifting out of OD and unlocking the torque converter. Sometimes when this would happen my trans temp light would go on and off I have an aftermarket gauge and it was not getting warm. This is what I have done so far.

Replace TPS (sprayed the old one real well with contact cleaner and the problem went away for a week then started again so I thought that was it)

Checked voltage on new tps(1. 0 @ idle 3. 6@ wot) Seems low to me not sure what it should be at WOT

Removed the TPS wires from harnes and rerouted them(PITA)

So after much thought I have looked at the obvious signs and figure the sending unit for the trans temp must be tied in there somehow thru the PCM So does anyone know how to eliminate it?

Figure I dont need the dummy light anymore and I would like to eliminate it as a source of trouble.

 

[Joe G.]

I had a trans temp sender fail some years ago on my '95. No OD. I replaced it and it's been good every since. Simple job. The main purpose of the sender is to let the PCM know when the ATF is warm. The idiot light is not worth anything because by the time it comes on its too late.

 

[BDech]

Good point I didnt think about those january warm ups here in MI maybee I better not eliminate it . The pcm holds the transmission in 3rd and no lockup untill warm . Correct?

 

[Joe G.]

Yeah, that's the main function of the sensor. The idiot light is just an extra added worthless attraction. I don't recall how much the sensor cost, but it wasn't much.

 

[Extreme1]

To diagnose the sensor, jump the connector with a paperclip. The sensor is in the line from the trqns to the block mounted cooler on the '94-'95's. That will eliminate one potential source.

 

[ronco]

Originally posted by Extreme1

To diagnose the sensor, jump the connector with a paperclip. The sensor is in the line from the trqns to the block mounted cooler on the '94-'95's. That will eliminate one potential source.

I disagree with Extreme on this one. I believe the proper method to bypass the stock trans. temp. sensor is to get a resistor of about 700 ohms (I found 680 ohms will work) and use that as a bypass. The resistance is crucial to proper functioning of convertor lock up.



Ronco

 

[BDech]

So at 680 ohms is that the resistance at start up when its cool or when its at about 180 and if its when warm do you know what it is when cool? Thanks alot

 

[ronco]

Originally posted by BDech

So at 680 ohms is that the resistance at start up when its cool or when its at about 180 and if its when warm do you know what it is when cool? Thanks alot

BDech,



I got the 700 ohm value off this board some time ago. When the factory sensor reads 700 ohms, the controller will allow O/D and T/C lockup at the preset speeds, if all else is working correctly. I do not know what temp. the 700 ohms corresponds to.



Ronco

 

[Joe G.]

I wonder if it is a good idea to disable the sensor for cold climates. Chrysler is not known for putting anything on that is not needed. They tend to leave needed stuff out to save money.

 

[ronco]

Joe, the sensor prevents the t/c from locking until a certain temp has been acheived. If you bypassed the sensor, you could drive slowly until temp is built in the trans or warm the truck up in Drive to achieve temp. We were discussing bypassing the sensor for diagnosis here.







Ronco

 

[Joe G.]

It was starting to read to me as if the recommendation was to replace the sensor with a resistor. That would work ok in a warm climate, but where your butt freezes to the ground every winter it might not be a good idea. A paper clip will check to see if the trans is the problem or not. It's been a while since I bought a sensor for mine, but I don't think it cost very much. Mine had a little leak so I just replaced it. The OD and lockup problems were cured and so was the little seepage leak.

 

[BDech]

I was asking about the cold resistance becouse I was considering going to a manual switch to facilitate warmup when needed.....

Thanks