What puts the tranny in limp mode? What happens while in limp mode? Is damage being done? 2004 6.0, torque shift tranny.

Thanks
Shocky

 

Never heard of 'limp' mode before...

 

well stay tuned then...we're both about to learn a thing or two...I hope.

FYI...torque converter wont allow tranny to shift because of an over torque situation. Common with tuners.

 

FYI the torque converter has no control over the trans. When the PCM tells the trans to shift, the torque converter can't prevent the shift.

Limp home mode is when the PCM detects a severe transmission problem. The PCM limits the transmission operation to try and prevent damage. A lot of people say that limp home is only a certain gear, but that isn't correct. The PCM decides what the trans can still do with the failure that it has, and uses what is still useable.

An example of limp home would be if the PCM detected that the pressure control solenoid that operates the overdrive clutch didn't work. In that case 2nd and 5th gears wouldn't work, so the trans will shift 1-3-4, since that's all that it can do.

 

I've never heard of a Torque shift going into or having a limp mode. The Allison trany (witnessed a 2002 DMax in limp mode) has a limp mode and it will go into limp mode with a tuner and a moderate to heavy load. It is controlled by the TCM and not the torque converter... Then again I could be wrong. I'm sure some one will correct me if I am.

 

The motor will go into limp-mode when certain operating parameters are met (not sure how the tranny is affected). For example, with cooling issues, it will not allow the motor over a certain RPM.

Hopefully, one of the techs will chime in, but I bet a search of "limp mode" will turn up something here or on the net. I know the motor has it, just do not know the specifics.

 

Just wish they had come up with a different name. 'Limp Mode' is not a very manly name for something on a diesel....

 

My 05 F-250 went into limp mode while driving once. While in limp mode it ran like it was governed at 50mph. The service department at the dealership said it was because the EGR valve was stuck. They replaced the EGR under warranty and I haven't had any more problems.

 

BBC, do you know what year models have this feature?

 

No... but I think all 6.0L motors have it - regardless of model year... its just a feature of the programing and the motor's capabilities (at least with Ford's programming being used in the PCM).

 

K, thanks dude!

 

Earlier Ford trucks had it too...thr tranny was the topic of this post...my '92 F250 would go into "limp home" mode when the vss module went out and also when the fluid level got too low. It would upshift really HARD and the overdrive lamp would blink to tell you it was in "limp home" mode. Codes would also show up when I took it in for repair....Can't really remember what they did...maybe changed fluid. Finally had to have the tranny overhauled - at about 150,000 miles. Never had the problem again.

 

I have a 2006 f150 and apparently it's in limp mode. It's shifts from 1st 2nd and 3rd fine but the second it shifts to 4th it feels like it's in nuetral unless I'm accelerating but the second I relieve pressure from the gas pedal it goes straight to nuetral and it's been like this for 3 the past days and the only thing I can find is its most likely one of the solenoids in my transmission that not allowing it to go into over drive so lastnight I get in my truck to go to work and I think we'll if it's doing this because it's trying to go into over drive let me turn my OD off and see if that does anything and to my surprise its driving great so I just wanted to share that and hopefully it'll help until u can get it fixed goodluck

 

Spratcat80: If you do have a F150, there is another forum for those trucks. This is the 6.0 Diesel Engine Forum - mostly F250s and F350s with some Vans and others with the engine in their rig.

This thread was just about ready to turn 10 years old btw... Good luck with your trans issue.

 

Newbeeeeees.