2004 allison
 

my 2004 hd started to make a noise that i thought was the turbo. An additional engine humb only at highway speed under load.but yesterday the tranny gave up.While cruising down the highway all of a sudden the trnny shifted down, not sure what gear but it was 50 mph at 3000rpm and will not shift up or down you can manually shift to park or reverse but not lower or higher going foreward,Does anyone know what is going on with it and how much im looking to spend on the repair or rebuild?Also the last few miles before it gave up the speedo started to bounce a little.This was the only warning that our noise was the tranny and not the engine.Any info would be great. thanks mark.

Re: 2004 allison
 

The speedo acting up means somthing in the VSS curcuit is not right. erratic vss signal can cause the transmission to not upshift. I whould get that fixed before condeming the transmission.

Re: 2004 allison
 

A Few things:

1. Have you changed your external tranny filter lately? It may be plugged up.
2. Are you getting any check engine codes? If so, what?
3. Is your shift indicator light accurate?

Re: 2004 allison
 

have you changed the fuel filter lately? Do you run a tuner that adds more horsepower? what's happened is, the trans has gone into "limp mode". It will only go into park reverse and third gear. If you have a tuner you can check the trouble codes to see what it is and even reset the code. If not, I believe you can just cycle thought the ignition sequence three times without starting the truck and it will reset the code.

Should you need a rebuild, you have one of the best allison guys in the country right in California. Mike Lovrich at Inglewood transmission can set you up with everything you need. Figure on about 2200 for parts plus the install.