Allison Tranny

dperry · February 26, 2007

A little history on the truck - Was partially flooded when I got it stuck in a wash - Truck ended up on its side. Insurance company totaled the truck and I bought it from them for salvage.

When we winched it back up on fours I started the vehical to help in getting it out. It seemed OK at the time. Once out of the ditch I also went ahead and drove it 4 miles to a place that would be OK to leave it before I could get a trailer to it. During the 4 miles had to go through a real sandy place and the truck almost did not make it. It seemed that the tranny started slipping bad.

The only parts that got wet has the drivers side. Got to the transfer case module and the airbag module. but other than that it did not make it to the BCM or the DIC. It also got the drivers door and the driver side rear door.

I have replaced the transfer case module and the airbag module along with the driver door module.

I did replace the ECM and reflashed. The TCM was under water but seems ok - unless this turns out to be the TCM.

Anyways - No engine codes but getting a P0722 and P0842. 722 points to the VSS and the 842 codes is low pressure on tranny.

I went through the checks and the VSS only showed 1200 ohms and it is bad.

Would this cause the low pressure on the tranny and thus basically having no forwards gears. I do have reverse.

I just now thought of another possible problem. I did check the tranny fluid and all seemed good. Looked clean and not burnt. While it was on it side it did leak a little. So it was a little low.

In doing the repairs I did damage the oil cooler - I had to replace the radiator support - and fender and hood. So once I started it back up. There was fluid leaking from the cooler - which I replaced - I did notice that the fluid in the tranny line was kinda milky. Which at the time I thought was air - but could be water now that I think about it. I was planning on changing the fluid but wanted a shop that has a tranny flusher so that all the fluid would be changed out.

I am asuming that the low pressure on the tranny is causing the basically no forwards gears - so once I get that fixed it can go get the other body work fixed and painted - then I can assemble the interior and will be done.

ryank1 · March 11, 2007

Water is a transmissions worst enemy. The glue that holds the clutches to there backing plate will brake down in water and the clutches will fail. This also holds true for the clutch in the convertor. Per GM if water is found in the trans, all clutches, seals and torque convertor must be replaced. Drop the pan on the trans and if you see that the fluid looks pink and milky or you find that the spacer plate gasket is sticking to the valve body, you have water contaim.