skongolf

I have a 2000 sub 2500 4x4 with 166k miles and just took 800 mile trip to salt lake where my sub ran great. No issues. Well today when I tried to back up a steep driveway I had some issues, but I think I just didn't let it warm up enough or it seemed to be flooding. Anyway, after driving about 15 min I started up a grade on the interstate and the tranny would not down shift. I got to 1500 rpm and dropped it into 3rd myself. At about 3500 rpm I put it back in D. Dropped to 1500 eventually and still no downshift. Doing it manually it shifted fine. After the grade and back on flats, no issues. I just flushed the tranny before I left. Any ideas?

in2pro

how'd the fluid look coming out when you flushed it, still pink or was it looking burnt?

skongolf

It was still a little pink but the guy who changed it said it was starting to look burnt. Now the service engine soon light is on, not the one in the message center though. Ughhh!!

in2pro

I have heard/read that if you start to see break down in a transmission that you're almost better off leaving and letting it fail at its own pace then changing the fluid as the shock can bring the end on quicker/immediately....

I believe also that if you are going to change the fluid in tranny take the time and do it right by replacing the filter as what you find in the pan will give a much better indication of the condition of the transmission....

What lead you to want to flush the tranny? preventitive maint or was it acting up?
if it was PM then something may have gone wrong with the flush (low fluid, air in the system filter knocked loose)... if it was acting up then most likely the flush just brought the end on quicker...

LARIDERS

flushing a trans seems to put a end to them. better to just drop the pan, change the filter and put new fluid in it.

skongolf

The flush was just preventative maintainance. I heard the same thing about doing a flush as well. When I drove back from Park City the tranny shifted fine. I went to autozone and pulled the code which was a p120 "throttle position sensor" issue. The guy said if the TPS goes out of wack in can make the tranny shift incorrectly. Anyway started back up after getting the code and no service engine light and the guy said that he did not reset the codes to turn it off. I will see what happens tomorrow but if it happens again I will probly replace the sensor. We'll see.

skongolf

OK still need some help. Yesterday driving back from salt lake my sub ran great. No issues downshifting automatically for the first 550 miles, then after a long run on the flats out of vegas to Kingman I lose auto downshift again. Shifts fine manually so the gears are still there. And when shifting manually the tranny is smooth. No codes popped up either. Will a bad TPS make it stop shifting automatically or are the shift solinoids going bad. Any ideas where to start?

skongolf

OK, pulled a p0122 code today. But now it is running ok again. Totally intermittent. Traced the wires and none were exposed. Guess I will clean the connectors next and see what happens in the next few days. Any other suggestions.