05 Transmission holds gears

[NoahDavis]

Hi all,

I have a 2005 3500 SRW with the 48RE transmission. Recently it started giving me trouble. It does not want to shift out of 1st to 2nd or 2nd to 3rd. I have to feather off the fuel pedal to get it to upshift, then sometimes it shifts back and forth from 1st to 2nd to 1st to 2nd. Same with 2nd to 3rd. Fluid is clean and nice, no check engine light. I took it to a transmission shop and they where nice, test drove the truck with a snap on computer recording the activity. Unfortunately, the tech knew less than I know about the Dodge truck transmissions and all of his diagnostics where in question.



One thing I noticed while the truck was on the computer is that the out output speed sensor signal was fluctuating a lot while road speed was constant. I know that these sensors sometimes have a certain amount of up down that is normal but not sure on this one. It would jump from 600 to 1100 to 800 ish.



There is a code p0731 and p0732 for incorrect 1st and 2nd gear ratios.



I am wondering of maybe the electronic throttle valve actuator is stuck or something. Is there a way to test it? If it is stuck, can it be removed and cleaned/repaired?



Any help will be appreciated.

 

[cerberusiam]

Governor pressure transducer and solenoid, those are the problematic pieces that cause what you are describing. You cannot get them to test bad or throw codes that indicate them most of the time. You just get weird companion codes and strange behaviour.

 

[Matt400]

One thing I noticed while the truck was on the computer is that the out output speed sensor signal was fluctuating a lot while road speed was constant.

There is a code p0731 and p0732 for incorrect 1st and 2nd gear ratios.

One thing thats odd is the two codes you mention are only listed in gas applications, maybe the tech didn't have the scanner configured properly for your truck. Those scanners require specific digits from the VIN# input to the unit so it basically tells the scanner what it is connected to.



Coincidentally those two fault codes can be caused by a bad input speed sensor. Sounds like you need a second opinion though and good place to start may be here.

 

[NoahDavis]

Problem solved

As far as the codes go, I may have remembered them wrong.



I have another Dodge and I figured that there is nothing easier to do than change out the output speed sensor with the other truck. It completely fixed the problem. Funny thing is, I put a pressure gauge on the governor test port before I changed the output speed sensor and it showed no pressure until about 50 mph, now pressure is normal, 1psi per mph, approx. Believe me, this truck was undriveable. $17. 00 fix and took about 5 minutes. Thanks to everyone who helped!