I just noticed this today while running some errands... the transmission won't lockup or go into fourth gear. The only thing I can think of is maybe it's related to the colder weather, which has been in the -5 to +5 range. I know it isn't supposed to do either until the trans fluid hits 120 deg, but I had been running quite a few errands, and I really don't see why it wouldn't be that warm by that time.

Any thoughts in case fluid temp isn't the problem? I checked the level and it appears fine (if bubbly), and in fact I changed the fluid and filter back in August and it's been working just fine since then.

Thanks!

Rob

 

mine does it too until it warms up....

 

Mine did that also, Then I took it to the dealer they charged me another $100 to reflash it, they said I was out of warrenty

 

how many miles are you driving it? it will take along time in that cold of temp to warm up. my service manual actually says that it should shift into od and lockup at 50 deg. i would say if you didnt have any problems until it got this cold that it is fine.
Jamie

 

My 03 just did the "not shift to 4th or OD" trick this last week. The dealer kept it telling me he thought it was a sensor. It's been in colder wx and hasn't done that. Drove it for 10 miles or better in 3rd. Drove it for two days checking. Should've warmed up. Temp outside in the mid 30's. I'll find out first of week what they want to tell me about the xmission, but in the mean time, they ripped the right rear quarter panel out of it. Hit a bollard, concrete post that holds up their drive through. That'll set em back. I'm driving one of their new Hemi's. Zippy little thing. Waiting to hear what you find out.

 

I'm glad it's not just my truck... because it's still doing it.

I tend to think it's a sensor too. There are times when it'll work okay, such as if I have it plugged in for a few hours, but otherwise, it pretty much doesn't anymore. It doesn't seem to get warm enough driving around town (low-speed stop and go), even for 30-40 minutes, to make it warm up enough to lock up or shift. It's really annoying.

I have just under 41k miles on it... should still be under warranty, as they tell me my powertrain is good til 70k and the motor of course til 100k.

Rob

 

I had this same problem awhile ago it was due to corrosion in the wireing harness. There was a TBS or Recall on the haness connections.

 

I was just going to comment. Mine was also the wiring harness. They're changing it and also the clock spring in the steering wheel. Not related to the upshift failure, but TSB on it evidently. Effects cruise control. Ain't life grand. They've still got to replace the bed from them tearing the side out of the truck. I'm thinking hard about leaving it with them and let them worry about it while I drive off the lot with one of their new ones they haven't broken.

 

I drive these cummins for demo's and when it's really cold (below 0 F) I can drive the 25 miles to work at road speeds without getting into OD must be the tranny cooler working too well.

 

I don't think that's normal. Too many instances of wiring harness changes making it different. I had mine changed and it hasn't done it since. Shifts into OD in approximately a mile...... first time I can get to that speed because of streets. Haven't had zero since changed, but it was also doing it at temps as high as 20.

 

Read the note on page 234 of owners manual.Torque converter clutch operation in cold weather.