tranny not shifting

[6.5peier]

I got a 93 k2500 6.5td and the transmission every once in a while will not shift out of second gear and sometimes when it does I will be driving along and it just seems to go into neutral, stop my foot into it and it grabs a gear and away you go again for a couple weeks. It only does this once in a while but when it works it works great even under heavy loads. Any help with this matter would be great

[dieselherb]

Could be the solenoids going.How many miles? Should change fluid every 30-60000 miles. You need to put a scanner on it to see if it has logged any codes.

[6.5peier]

the truck has about 150k miles on it and the only codes that it has are 86 & 87 which is a low ratio error and a hight ratio error its got me really confused the other night i move a truck on a trailer....the thing never missed a beat the whole time i was pullin...went and unhooked the trailer and was driving home and it starts actin up...is there any chance it could be something to do with the tps (throttle position sensor) cause it does it more with no load on it

[C-Power]

i had my tps sencer go out a month or so back ( look at no od by c-power) it sounds kinda the same check your connection then ometer it....if you have a current in and out of the connection then its probly the sencer its self....

[jhooten]

Those are the same two codes shown when the TPS went out in mine.

[Colorado Cowboy]

This may sound funny, but when was the last time you cleaned and tightened your battery cables. My truck began having all kinds of problems. One was the tranny would default to 2nd gear after running fine. It would then work properly again sometimes a couple miles down road, sometimes after I shut it down and restarted. I also had erratic throttle over 65 mph. At times mostly under load, the tranny would not shift from 3rd to OD unless I let off the throttle. Turns out I had a loose positive cable on the passenger side battery. Cleaned and tightened all 4 cables, and no more problems.:D

Colorado Cowboy
1997 K3500 Crew Cab Dually

[synthetic-oil]

the truck has about 150k miles on it and the only codes that it has are 86 & 87 which is a low ratio error and a hight ratio error its got me really confused the other night i move a truck on a trailer....the thing never missed a beat the whole time i was pullin...went and unhooked the trailer and was driving home and it starts actin up...is there any chance it could be something to do with the tps (throttle position sensor) cause it does it more with no load on it

In my GM service manual and also in the ATSG 4L80E manual The codes are:
86 B solenoid stuck on
87 B solenoid stuck off

[6.5peier]

I got those codes from a site here on the net kennedy diesel site...it is quite possible that they are not the right ones

[jdozier]

I am having a some what similar (but maybe not) issue with my 1994 Sierra 2500 "New 6.5" in that when I start up for about the first three miles or so everything shifts and works great, then the sucker locks in second gear.. I have had it checked and been told that it is throwing high and low gear ratio error codes......
Does anyone think that this one is shot (I was told it had recently been rebuilt when I bought the truck true or not) should I get it rebuilt....?

I have already changed out the selenoids, speed sensor, and ignition switch.
Anybody got a clue on this one....????

Could it really be thr TPS, as mentioned before in this thread...?

[grancito]

Try a search on that, it is in limp mode, I think something to do with a temperature sensor, someone posted this maybe 2 months ago, I think it is in the transmission.