Engine/Transmission (1994 - 1998) can't figure this one , help me out guys

[champspa]

went tractor pulling this Sunday and truck was shifting fine , about a hundred miles down the truck wouldn't shift into low or second , I could manually pull it into 1st but it was in 2nd gear. went and came with 2nd as lowest gear. got home unloaded, backed the trailer to it's spot and now it's working in first both pulling it into first and auto shifting. can't figure it . I unhooked the brakes and backed up then it went to working what do you all think?

 

[champspa]

well I asked my transmission man today , he said if it sets a code it won't shift into those gears . just as it was doing . checked today and it had code 12,37,37,45 and 55 in that order , the question is will the mystery switch set those codes? 12 and 55 are of no consequence the others are the problem

 

[24valver]

I had the same problem on my Mom's 97. Turned out to be the solenoid that controls the 1st and 2nd shifts. I think it was called a govenor solenoid, but I'm not 100% certain. After I replaced it, the trans worked fine. Hope this helps.

 

[Bart]

Please correct me if I'm wrong, but I didn't think the 12 valvers had a computer. I'm under the impression that it an all mechanical diesel. I only state this because I have the last of the 12 v'rs and would like to know if I'm in error. If it has one where is it located?

 

[champspa]

transmission is computer controlled from 96 up

 

[Missouri Mule]

I'll second champspa.

 

[Howard Durand]

Transmissions in the 94 and 95 have the 47RH transmissions. The OD and TC solenoids are controlled by the PCM which is a computer.

The PCM receives a signal voltage from the throttle position sensor that determines the vehicle speeds at which the OD and TC solenoids are allowed to operate. I believe that this is pretty much how the 47RE works too except that it takes the electronic control a bit further.

Beyond that I can't tell you much.

I think champspa is concerned about the manual TC lockup switch possibly causing some of his problems.

I use the TC lockup switch and have never experienced any problems from it's use but can't say if there is a problem with the RE.



Bart, I am sure your 98 has one. You should find it on the passenger side firewall behind the air filter. I think yours has 3 separate cables that plug into it.

 

[JoeBioDiesel]

You need to check your governor pressure. You can do it with a diagnostic scanner plugged into the connector under the dash, or check it with a pressure gauge attached to governor pressure port. I bet the reading is too high... reading pressure with the truck sitting still. The likely cure is replacing the governor pressure solenoid on the valve body.

Joe

 

[champspa]

Ok guys , I found out what it was . the transmission will go into default mode which hasn't any 1st and 2nd , except when manually pulled into 1st which will go no lower than 2nd , when codes are set in the computer like code 37 which said [transmission overdrive circuit failure] basically I used my mystery switch to open the overdrive circuit. My fault but thanks for all your input