Transmission problems?

[jnmcinnis]

Hi-

My truck has apout 131,324 miles on it and sometimes the o/d light will start flashing and it will shift hard I heard that this was called limp mode where the computer will put all computer controled pressures in the tranny on high to prevent damage or somthing along those lines. Anyways it dont do it often but now i can be trying to take of and it feels like its going to go then all of a sudden it just dont want to move then i can put my foot into it and it will move. What can cause all of this also I think the fluid is worn because it has a blackish tint when wiped on a paper towel also it has a funny smell to it. I want to change it but heard that its a bad idea what is ya'llake on this also?
Its very fustrating

 

[Tedybear]

The O/D light is most likely flashing an error code. (not sure exactly what/why, might be something in the research dept on the site)

From the sounds of what you are describing? I'd say it's time to either rebuild your unit, or replacement. The black tint, along with a heavy smell normally equals clutch or band overheat/fail. (the one we are working on our BII lost most of reverse, and only had strong 1st gear...the fluid stank!! and was jet brown/black.)

You can try changing out the fluid, although given the nature of what would be needed? I'd drop the pan first, and inspect the filter for buildup..and the bottom of the pan for metal leftovers. The best way to correctly flush things out? Would be in my opinion a two fold approach. Fluid exchange, followed by filter. The torque converter (unless it has a drain plug) will retain up to 4-6 qts of ATF. Just dropping the pan? Nets about 1/3-almost 1/2 the total. So the rest of the junk fluid is still stuck in the system.

? If you put it into manual first gear, will it move normally? If so? This is normally a sign of a bad one way clutch in the unit. Putting it into manual first will engage a clutch pack that does basically the same thing as the one-way clutch. If all the sudden it moves forward normally, but won't do it in just normal "D"? High chance the one way clutch has done what is best described as "self-destruct".

The computer's limp mode is not designed nor meant to allow more then driving it to a shop/dealership to correct the problem. In many cases, once that light starts to flash? The damage has already been done The computer is just recording the damage to the driver/owner.

This could be anything from a toasted one-way clutch (unless exempted by that test listed) It could be torque converter fail... Internal pump fail...etc.. Could also be a plugged filter. (keep in mind, if that filter is plugged? What plugs a transmission filter? Worn band/clutch material...if it's got a good share in it? The transmission should be rebuilt...as just swapping out the filter and fluid? Might help short term--but the excessive wear has already shown itself)

S-

PS: At this point there is, in my opinion only...no further harm that can be done by changing out the fluid/filter. The transmission is already acting up.

 

[jnmcinnis]

It Moves normally when shifted into first gear and it also moves normally when in D it goes through all the gears it just shifts hard ill have to drop the pan and see what that looks like.