Transmission won't downshift...

[enkrypt3d]

I'm not sure if it just needs service or if there is some throttle position sensor that I need to replace but even when I have OD turned off, I have to floor it to get it to downshift into 1st or 2nd.... it seems like it stays in 2nd or 3rd most of the time unless I'm at a total stop... any clues to why this is? Thanks!

[Precise1]

#1 Check the level and quality of the ATF.

#2 Do you have an external cooler or are you still routed through the radiator cooler?

#3 Confirm that you have proper flow going back to the tranny. (You can temp bypass any coolers you have set up)

#4 Reference the FSM for the tranny diagnostics, they can be read like the ECU.

 

B

[cvdloc]

This is like an issue I had in my pathy, twice before each auto trans went. I usually stopped and let it cool down and it would be fine. But it got so bad even stopped it wouldn't downshift.

[enkrypt3d]

#1 Check the level and quality of the ATF.

#2 Do you have an external cooler or are you still routed through the radiator cooler?

#3 Confirm that you have proper flow going back to the tranny. (You can temp bypass any coolers you have set up)

#4 Reference the FSM for the tranny diagnostics, they can be read like the ECU.

 

B

 

The last time it was serviced the tech said that flushing the transmission fluid might do more harm than good if the trans is working fine (as it was at the time)..... I'm hoping that the flush will help and isn't too expensive. I have done the diag sequence before but not since this started happening. The truck sat in the garage for a while not being driven on a daily basis for almost a year but I made sure to drive it on the weekends.... it seemed that it sitting for a while and driving it again on a daily basis that it wasn't as peppy as it used to be.

 

This is like an issue I had in my pathy, twice before each auto trans went. I usually stopped and let it cool down and it would be fine. But it got so bad even stopped it wouldn't downshift.

What was the solution you found for this issue?

 

Edited April 6, 2014 by enkrypt3d

[Precise1]

Flushing, and just changing the fluid is two different things. I don't buy that 'just run it until it dies' crap. ATF is basically hydraulic fluid with lubricants and detergents. It can get dirty and heat breaks it down. To say not to change it makes no sense to me. What doesn the FSM say about the maintenance?

 

I'm not an auto tranny guru, but logic prevails here. The ATF needs to be in good condition, at the right level and the flow needs to be unobstructed. If you don't verify these items, you have nothing to go on.

I have set my tranny up with a temp gauge, a spin on/inline filter and auxiliary cooler. This is so I can watch the temp (temp breaks down the ATF), I can make sure there is no significant particulate matter in the fluid, and that the fluid gets a chance to cool. Very soon I will reroute the lines so they will go through the filter, into the radiator cooler, and then into the larger auxiliary cooler I plan to install. This should provide the most stable operating temperature and provide the most cooling at the same time.

 

If you have shifting issues, I highly recommend you address them before you don't have a working tranny.

 

B

[enkrypt3d]

Yea I'm collecting some new parts along with things that need to be replaced MAF sensor, starter relay, springs, shocks and new rims and tires eventually.... but this needs to be done first to service the trans...

[cvdloc]

Well the first time got a junk yard auto trans and swapped it out, second time I swapped in a manual

 

I agree with was Precise1 is saying, one test you can do is when your having these issues stop and smell your auto trans fluid via the dip stick. If it smells burnt, well that ain't good.

 

I'll admit when I first came across these issues I didn't address the issue, come to think of it what I would have done differently is when I swapped in the first auto trans would have been to instal an auto temp gauge and and after market trans cooler. These two things would have probably saved the second trans. One thing you can do right away is do the temp gauge, it isn't hard to do and that might save any more damage cause once it starts rising you can cut it and let it cool down.