Allison problem

[Somis Duramax]

Good Morning,3 times now after being cold here (20's F)after my 03 has been warmed up for 5 minutes and going down the road, about 1/2 mile the SES lite comes on. Stop at stop light and when going to take off truck acts if it is in 3/4 gear,slipping like crazy. After you get up to about 15-20 mph it quits slipping and works ok. Turn around to go home and stopped truck and restarted and it worked fine. Pulled codes P0763,0768,0773. Reset them and its works fine. Truck has also had an occasional U2106 which after being reset goes away, it also has the black NSBU switch. I was going to change switch for the U2106 but now that
the other problem has arisen I am wondering if any damage has been done to trans.Fluid is still nice and red and the truck has 15k on it. U2106 puts trans in limp mode but the new codes do not.
Any ideas?

Thank you

[403turbo]

Well I would start with the NSBU switch. This is a known issue and is fairly easy to replace.

Did mine in the driveway, at night, with a flashlight.....so inside during the day with a work light has got to be easier.

Anyway, that would be my first action, if you go to the dealer they will do it anyway and charge you for it.

Cold weather usually means salt and wet roads, perfect conditions to kill that black NSBU switch.

Give it a shot.

Someone else may have had these symtoms before ad will pipe up.

[403turbo]

sorry didn't see that you only had 15K, go to dealer and raise a stink!

Dealer can replace NSBU, no charge

[REC06]

Mine did the same thing, 32,000 miles. Replaced the nsbu, reset codes I was fine for 2 or 3 days. Started over again got those codes and more. J.B. DLCO Allison dealer has it out and on the bench. They said all electrical checked out, found wear material in the internal filter. Waiting for the final report. Best part I got a dealer to sub lease the work out to the Allison shop. Just taking to long.

[REC06]

Got the truck back a few days ago. All is fine now. Tech said the c2 clutches were GONE, the t.c was near failer and a couple of other odds and ende. Replaced with a new style t.c from allision and the clutch packs were also replace. He did note that while road testing it seemed that my trans would not lock up when it should. Tow haul or regular didn't matter. I am going to have to drive it with a tech 2 on it and see when it does and does not. Maybe there is a tcm update that will help. I could not convince the tech to install after market t.c., valve body, or cluth packs. I was hoping to save labor cost.

[max out]

REC06, how do them 255's fit the truck, did you have to do any trimming or torsion bar adjustments?

[Somis Duramax]

Well I changed the switch on my dime and all was well for a week. Yesterday while driving trans went into limp mode,no SES lite but got ABS and brake warning. U2106 was stored. Off to the dealer.

[mdrag]

Somis Duramax,

Has the Allison spin on filter been changed? Although Allison recommends changing the spin on @ 5K, GM did not include this in the routine maintenance schedule. A drain/refill of the ATF is not required @ 5k, just replace what is lost while servicing the Allison spin on filter. Good luck.

[Somis Duramax]

Mdrag, It was changed at 500, 5k and at 15k.

[REC06]

Max Out,
The tires fit fine. No trimming or torsion bar adjustment, I had the bars cranked up a couple of turns already. The tires themselves are great. I don't get stuck unless I frame out. They were pretty quite new, but now they are noisy and bug me all the time. I am getting uneven wear, even though I rotate and balance every 5k. The last time in the service guys said they barley got them balanced (I don