HOW TO: 45RFE transmission transducer pressure sensor

[uss2defiant]

Part number:

New superseded part number is 4799758AD.

Cheapest I could find was for $46.28 & FREE Shipping on amazon (I found this after placing my other from my usual mopar source).
Amazon.com: Chrysler, PRESSURE SENSOR TRANSDUCE, 4799758AD: Automotive

The transmission transducer pressure sensor is located on the passenger side of the transmission.

Reason for replacement:

• Noticed leaking transmission fluid. The fluid soaked the rear part of the ****** pan and dripped ATF on the ground from the driver side even though the sensor is on the passenger side, YMMV.
  
• Hard downshift from 2nd to 1st gear.

Tools:

1/4" ratchet + 8 mm deep socket.

Steps:

1. Pull red connector locking tab in the direction of away from transmission.
2. Depress the locking tab and pull connector in the direction of away from the transmission and tuck it on top of the exhaust pipe next to it.
3. Use tool to remove nut.
4. Pull sensor out. (before pulling sensor out, put some paper towel, old newspaper, old underwear, catch pan to catch some ****** fluid that will come out. It wont be pouring but some drippage, YMMV)
5. Put some ****** fluid on o-rings on new sensor.
6. Clean area where sensor sits and install new sensor.
7. Rebolt the 8mm bolt (hand tight)
8. Clean off any ATF on connector.
9. Reinstall connector.

Pictures of old sensor:

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Another view of it,

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Notes:

The o-rings on the pressure sensor are not serviceable unlike the 2 transmission speed sensors on the driver side.

Both speed sensors are the same and the part number is 4799061AB.
The O-ring part number for them is 4799062.

I noticed that I was able to wiggle the transducer part (metal cylinder shaped end) while holding the connector side. I don't know whether this is the same case for a new sensor. While noticing that, I noticed a pin hole sized leak on the seal. You could possibly put some silicone sealant or rtv if you experience that too.

I measured the o-ring on the new pressure sensor with a digital caliper in case someone else would like to try replacing the o-ring.

The inner diameter has to be minimum 6.19 mm. (6.19mm was the diameter of the part that the o-ring fits on to.)
The outer diameter of the o-ring was 11.35 mm while on the sensor.
The old o-ring was approximately 2.5 mm wide.
*The o-ring is blue in color.

I did not want to risk breaking the new o-ring just to measure it.

I have extra Multipurpose Chemical-Resistant O-Ring, Viton® Fluoroelastomer, 2.5mm Wide, 6mm ID I ordered from McMaster-carr if you'd like to try replacing o-rings first.

Another thing, the 45RFE requires cycling through all the gears and ending at Park, NOT neutral, to check the ATF level. Checking the ATF level in neutral is for the 42RLE.

 

[ltd02]

This "how to" helped a whole lot!!!

Changed the o-rings today. Not a difficult task and the old ones were toast. Very brittle. I had a whole lot of those 2.5mm x 6mm Viton rings for some reason and they worked fine. Used a small pick to remove the old ones but could just rip them off with a small screwdriver. The new ones were a bit stiff in the cold of my unheated garage but I did manage to roll them on without breaking them. The inner one was tricky but I had a bag of 50 so just went for it. I checked that silicone seal and it looked fine. I believe my pesky ****** leak was from this sensor, running down to the pan lip and across to the driver side making me think it was the pan gasket. Time will tell.

 

[uss2defiant]

Cool.
I thought you were just going to buy a whole new sensor instead of the o-ring route. no?
I don't remember what you said last but did you check your two speed sensors as well?

My pan has been dry since the new sensor was installed.
However, I did start getting a hard downshift after the new sensor from 2nd to 1st gear.

It took about 400-500 miles for the jeep to relearn by itself.

 

[ltd02]

Cool.
I thought you were just going to buy a whole new sensor instead of the o-ring route. no?
I don't remember what you said last but did you check your two speed sensors as well?

My pan has been dry since the new sensor was installed.
However, I did start getting a hard downshift after the new sensor from 2nd to 1st gear.

It took about 400-500 miles for the jeep to relearn by itself.

I was going to but never ordered the sensor. Wanted to get a better look at mine first. I was under there doing an oil change and re-torquing the ****** pan bolts and saw it was definitely wet around the connector. Unplugged everything and and it was clearly leaking. It seems to be functioning fine and I found this baggie of o-rings so figured I'd pull it and see what it looked like. They were the exact size you stated and the Viton variety. I think I had them from when I did some fuel line work on my Ranger. No leak around the outer silicone seal on the sensor, it was solid, but the o-rings were toast. They may have been blue but had faded to a very pale blue/white-ish color. The new ones fit very well and the sensor went back in smooth and felt secure even before tightening the bolt. I'd recommend doing this in a warmer spot as the o-rings really have to stretch to get over the sensor end. Checked this morning and no drips yet. Only a very small amount of ATF+4 came out so I'll top it off today if it needs it.

Almost forgot, The speed sensors looked great. Dry as could be. Are they the same size o-ring?

I think I have recently noticed the downshift from 2nd to 1st but only does it when cold. Might do it for the first 2-3 opportunities and then stops. Subtle, not very harsh but I can feel it. If it gets worse I'll swap the sensor. I also have the Sonnax line booster on mine and that seemed to help firm up all my shifts. Don't think the computer ever learned around that since it still shifts way better than before I installed it.

 

[uss2defiant]

ah....

Sorry, I haven't had a need to change those speed sensors, however, those O-rings are serviceable and you can purchase them from MOPAR, see my first post.

If they're cheap enough, I'll order a set w/ my TSB fix kit to my foaming issue.

 

[fishyx]

I changed the O-rings on mine and still getting a leak from the sensor itself. The body of the sensor seems to be a two piece design that can loosen up over time and break what appears to be a RTV seal. Just got a cheap one on ebay but haven't had a chance to install it yet.

 

[uss2defiant]

yeah. mine leaked through the sensor and into the connector so I replaced mine completely.

 

[fishyx]

So far so good with the $12.00 ebay sensor. Pretty amazing how much trans fluid was leaking out of the old sensor. What really surprised me was how all the fluid made its way to the drivers side which made it appear like the leak was on that side.

 

[crdjon]

So far so good with the $12.00 ebay sensor. Pretty amazing how much trans fluid was leaking out of the old sensor. What really surprised me was how all the fluid made its way to the drivers side which made it appear like the leak was on that side.

Me too.