Won't shift into overdrive when cold

[grbow]

I have had a shift problem off and on for awhile now along with a 2127 code. I have noticed for the past week if I plug the truck in overnight it shifts fine and the check engine light goes off. If I don't plug in the truck it won't shift into overdrive for 10-20 miles. I was thinking connections/ground on the tpps but the cold/ warm thing has me wondering. anyone else have this?



2004. 5 3500 srw quad cab long bed... stock

 

[retirednak]

Its normal for our trucks to not shift into OD till some heat is built up. My '03 does the same thing when I have to park outside. Even plugged in for the 4 hrs on my timmer and its -10 and colder,my truck still doesn't shift into OD for a few miles. My truck has done this since I owned it and now that I think about it,the stealership gave me the same advice. I don't think you need to worry about it.



Throwing a code is a different issue, your code is "Pedal Validation Switch 2 Low" Somebody more smarter them me will have to hep you out.



Good luck-Casey

 

[rbattelle]

If the fluid temperature is below 30°F, the transmission controller prevents engagement of the converter clutch and the overdrive clutch.

However, code P2127 suggests your APPS might be bad.

Ryan

 

[grbow]

But it seems like the code and shift problem are related, When I start my truck in the morning and the check engine light is off I know it is gonna shift... when it's on I know it aint... have been reading about some possible connection/ground problems with pps so going to remove it, clean and inspect connections and go from there. And thanks guys, I didn't know about the cold trans fluid thing, just bought this truck in Nov and am a first time diesel owner.

 

[cerberusiam]

The APPS is under the hood on your truck and that is a harsh environment for an electronic piece. Its not uncommon you get those intermittent codes under certain circumstances when the APPS is getting bad.



Pluggng the truck in will pre-warm the coolant and trans fluid so its above the minimum temp, plus, the extra underhood heat makes the electronics react differently so you don't see the problems a cold start shows.

 

[candyman_007]

Grbow,

I had that issue of p2127 last year, and I to was baffled for awhile thinking it was temperature related, but wasn't, I replaced the APPS($400+) and it wasn't sending the P2127 no more. Bite the bullet, and get new APPS.

 

[grbow]

Candyman



Yeah, figured I would have to do that. I'm not having any problems since the weather has warmed up but planning to replace it before cold returns. Thanks