Allison 5sp: truck will not move

[JMK777]

I just picked up a 02 with my brother last week. I was getting the disappearing indicator light so i change the NSBU and that fixed that, the 4x4 button wont go into 4h or 4l and the service 4x4 light is on. The truck wont move at all when in any gear.

I was getting p0842 and p0700 and u1000. It came with those codes so I cleared them and charged the batteries which where dead and nothing came back.

What I Have done so far is change nsbu, pull pan and changed filters, pulled solenoids and checked for clogs and they where clean, checked/tested pressure switch manifold and it works. There was very little crap in the pan no chunks or shavings at all.
I then put it back together and still wont move. no codes have came back either.

my next attempt will be pull valve body, tear down clean and re assemble unless any other ideas before i dig into it again?
I have a feeling i should be looking into the transfer case before valve body.

 

[Mike L.]

Does it grind going into park?

 

[JMK777]

Does it grind going into park?

No. no odd or bad sounds at all. when you put it into gear the idle go's down like its going to move but no movement at all.

 

[JMK777]

could the converter be shot that bad?
but if the converter went out it should have taken other shit with it right?

 

[Kspen90]

I would think transfer case or tcm but im far from an automatic trans expert

 

[x MadMAX DIESEL]

I think it sounds like the transfercase too

 

[JMK777]

I'm starting to believe Its my transfer case. the 4x4 switch in the cab did not work until I unplugged the harness that gos to the transfer case selector motor. when i plugged it back in you could hear the motor being controlled by the 4x4 switch, so i think the switch is not bad. But it stopped working shortly after and truck still wont move.

I than used efi dvt's to cycle all solenoids and i could hear them all except for "G" but I don't think "G" was added till the end of 03 and this is a 02. With the engine running I than locked the converter in park and it killed the engine. I then locked it in drive and nothing, still no movement
I then checked dtc's with laptop/efi and got a c0308 (motor a/b circuit low)

I think the T-case is coming out next.

any thoughts from the experts?

 

[DAVe3283]

That is really sounding like the transfer case to me (but I am not an expert).

 

[JMK777]

Case is out and its not the problem. Valve body coming out next for cleaning and inspection now

 

[JMK777]

just pulled V.B. and there was a small amount of gritty crap on top of it. about to split it.

 

[JMK777]

OK. just re installed valve body after tearing it down, cleaned and inspect. I tried to start engine and put it into gear (let it run in gear only for 5 sec. or so) without the transfer case on and still nothing. the pump must be working because fluid is pumping out the out put shaft. do i need to have the transfer case on so i can hook up the speed sensor?

Will the trans go into gear with out the speed sensor hooked up?

 

[Mike L.]

OK. just re installed valve body after tearing it down, cleaned and inspect. I tried to start engine and put it into gear (let it run in gear only for 5 sec. or so) without the transfer case on and still nothing. the pump must be working because fluid is pumping out the out put shaft. do i need to have the transfer case on so i can hook up the speed sensor?

Will the trans go into gear with out the speed sensor hooked up?

Yes. it will code when you try to accelerate.

 

[Kspen90]

Tcm maybe?

 

[JMK777]

Picking up a tech 2.

 

[JMK777]

well it just might be the tcm. I'm getting about 250 psi from the pump so that looks ok. might swap tcm's or do a re flash.

 

[JMK777]

just reset as much of the tcm as i could with efi. started the truck and got 2 rotations out of the out put shaft than nothing. and still get a C0308.

 

[gmduramax]

Stupid question but is there enough fluid in the transmission?

 

[x MadMAX DIESEL]

Stupid question but is there enough fluid in the transmission?

That's the first thing I was gonna ask too but I'm they would check that after pulling the pan.

Sent from my PC36100 using Tapatalk

 

[JMK777]

Yes. There is enough fluid. I when i got the t case back on i let it run in park for 5 minutes then cycled the gears for 5 seconds each and repeated for a while.

 

[JMK777]

Well its Not the tcm. I just swapped it out and nothing. Still got the service 4 wheel drive light too. I need to check out the t-case shift motor and the sensors on the t-case. is there a way to check the sensors with a meeter ?