Allison 5 speed no engagement. Input shaft?

[GMCSLEHD]

Have a 2004 LB7 with the 5 speed Allison 1000. 113,000 miles on it. Transgo shift kit, Suncoast clutches and triple lock torque converter, Co-Pilot. Run about 460hp/950tq EFI Live tune daily.

Goose the throttle coming off a left turn and CLUNK, engine starts to rev, no output to rear tires. Coast into a Park and Ride, and find out Allison won't engage any of the gears, including Reverse. It's like I'm stuck in neutral, but Park works.

Not getting a CEL/SES light. No codes when checking with EFI Live. No unusual noise from transmission. Gear display on dash works, no blinking. No clutch material or metal debris in trans pan.

Replaced NSBU, no luck. Replaced Pressure Manifold Switch, no luck.Checked all the fuses and connectors I could think of, no luck. Bypass Co-Pilot, no luck.

Park engages transmission and holds truck. All other gear selector positions equal Neutral or no transmission engagement.

Torque converter spins when engine is running.

Without the truck running, took the PTO cover off and put the gear selector in Drive, turning a rear tire, I can see rotating assembly (C3?) move, but torque converter doesn't spin (I guess it shouldn't without motor running).

Am I looking at a broken input shaft? Any way to check it before pulling transmission? Possible electrical ghost?

Any input appreciated!

Thanks,
Josh P.

 

[Mr.T]

I'd say with almost certainty that your input is broken

 

[Runaway]

If the transmission light on your cluster display illuminates then goes out once the truck is started then there will be no stored diagnostic codes. However if the light was to remain after engine is started then a stored DTC would be indication of a error, or the TCM is malfunctioning...

Depending on where if at all the input shaft has been broken, with the engine running do a line pressure test. This should give you a good indication if the input shaft is broken.

Hope this was helpful and good luck

 

[GMCSLEHD]

Thanks guys.

Going to pick up a test guage and try that out today.

I'm guessing it would be OK to use the test port by the spin on filter?

-Josh P.

 

[Mike L.]

If the transmission light on your cluster display illuminates then goes out once the truck is started then there will be no stored diagnostic codes. However if the light was to remain after engine is started then a stored DTC would be indication of a error, or the TCM is malfunctioning...

Depending on where if at all the input shaft has been broken, with the engine running do a line pressure test. This should give you a good indication if the input shaft is broken.

Hope this was helpful and good luck

Why would line pressure change with broken input shaft?

 

[gmc502]

i'd look at the transfer case.try 4 low and see if truck moves.

 

[duratothemax]

Why would line pressure change with broken input shaft?

x2.

Even with a broken input, the pump is still going to spin!!

 

[Mike L.]

i'd look at the transfer case.try 4 low and see if truck moves.

Park works therefore it is not transfer case.

 

[duratothemax]

Park works therefore it is not transfer case.

Although if something lets go inside the transfer case, couldnt the truck still move in park?

Josh- I think EFILive can log turbine speed. Start the truck up and see what turbine speed reads. It should read roughly idle speed in park/neutral, and drop to 0rpm when the trans is put in drive with foot on the brake.

I think your output shaft is broken. Because if the input shaft was broken, you would still have park. If the truck is able to be pushed around in park, either something exploded in the xfer case, or broken output shaft.

 

[Chevy1925]

Park engages transmission and holds truck. All other gear selector positions equal Neutral or no transmission engagement.

Any input appreciated!

Thanks,
Josh P.

I think your output shaft is broken. Because if the input shaft was broken, you would still have park. If the truck is able to be pushed around in park, either something exploded in the xfer case, or broken output shaft.

He said park holds the truck

 

[Mike L.]

Ben if it was transfer case or output shaft, or disconnected drive shaft; you would not have any way of stopping the mainshaft from turning and it would grind going into park.

 

[duratothemax]

He said park holds the truck

AHH!! OOPS!!! Im an idiot. I misread/glossed over that and read quickly as "park rolls the truck"...meaning the truck still rolls when in park. (in which case it would be transfer case or output shaft)

My mistake...I apologize for throwing the thread off.

 

[Mike L.]

AHH!! OOPS!!! Im an idiot. I misread/glossed over that and read quickly as "park rolls the truck"...meaning the truck still rolls when in park. (in which case it would be transfer case or output shaft)

My mistake...I apologize for throwing the thread off.

Don't ever let it happen again.:toetap::roflmao::hug:

 

[duratothemax]

Don't ever let it happen again.:toetap::roflmao::hug:

I had "broken output shafts" on my mind for some reason. :



I know that sounds like a personal problem though. :roflmao:

 

[Runaway]

If the C3 clutch assembly is spinning when the drive shaft is turning then there shouldn't be anything broken there back. However if the input shaft was broken (depending on location of the brake) the pump would not be spinning, is my logic behind what i posted earlier.
when doing a line pressure test you should have in park/neutral @ 1200rpm 220-260psig. Again depending on where if at all the input shaft is broken you may still have line pressure.

 

[Chevy1925]

AHH!! OOPS!!! Im an idiot. I misread/glossed over that and read quickly as "park rolls the truck"...meaning the truck still rolls when in park. (in which case it would be transfer case or output shaft)

My mistake...I apologize for throwing the thread off.

Lol i figured you must have just missed it

 

[GMCSLEHD]

Alrighty then....

I checked pressure at the port by the Allison spin-on. Was a one thousand psi gauge, so best I can tell, was seeing around 270 psi in Park and Drive.

So I'm gathering from the discussion, that I still need to pull the trans and expect a broken output (DOH! MEANT INPUT) shaft.

In the version of EFI Live that I have, the turbine speed PID is not an option. I have to check and see if I can update to a newer version where it is enabled.

Thank you to everyone for their input. I will keep updated.

 

[Mike L.]

If the C3 clutch assembly is spinning when the drive shaft is turning then there shouldn't be anything broken there back. However if the input shaft was broken (depending on location of the brake) the pump would not be spinning, is my logic behind what i posted earlier.
when doing a line pressure test you should have in park/neutral @ 1200rpm 220-260psig. Again depending on where if at all the input shaft is broken you may still have line pressure.

You need to take some transmission classes before you start posting about them. Pump is driven by the engine by way of the torque converter hub. Input shaft is totaly divorced from the pump and has no bearing on pump pressure. Input shaft on Allison always breaks in the same place; at the void behind the turbine splines. C3 clutches do not spin. Now stop posting this crap.

 

[Chevy1925]

No, you need to expect to find a broken INPUT shaft

 

[02CCSB]

you need to take some transmission classes before you start posting about them. Pump is driven by the engine by way of the torque converter hub. Input shaft is totaly divorced from the pump and has no bearing on pump pressure. Input shaft on allison always breaks in the same place; at the void behind the turbine splines. C3 clutches do not spin. Now stop posting this crap.

like :d