Another 735 Code

[Roy W]

Got another 735 code the other day while towing my 10K travel trailer. Cleared code and truck ran fine. At the campground I disconnected my Edge EZ and my Boost Stick. Towed home in OD without any further problems. Now another strange happening: The check engine light has also come on twice in the last month. Both times not towing anything on the open road and the truck continued to run smoothly with no problems. Checked the fault code and it was another 735 !!!! I've also gotten two or three "shift range inhibited" messages when selecting reverse. Cycling the key a couple of times cleared that fault. WHAT'S GOING ON WITH MY ALLISON ?????

[More Power]

Roy,

P0735- Incorrect 5th Gear Ratio - This DTC sets when your truck's TCM senses that either the torque converter or the 5th gear clutch packs are slipping. Typically worn or slipping C2 clutch packs are the cause, but this DTC could also be due to the C3 clutches as well.

[Kennedy]

I think I posted comments regarding this before?

Simply put, the combination of the Edge and the Boost stick upsets the transmission. I have on numerous occasions set up ECM programming that performs as good or better in place of this setup and eliminated the issue, BUT the longer the truck is driven the greater the damage and the less holding capacity the C3 clutches will have.

The "box" is supposed to have slip protect and it does. In most cases it can pull back the power before the slip becomes severe, BUT the transmission often ends up dying the death of a thousand paper cuts as the module will frequently slip and correct.