LBZ- Shift Range Inhibitor

[Crump]

Hello everyone,
I have a 2007 Chevy Silverado 2500HD 6.6L with a 6 speed Allison. The other day I put the truck into reverse to back out of the drive and then back into drive to leave and it through up the "Shift Range Inhibitor" on the dash. I have taken this truck to two transmission shops here locally and a electrical shop do to a recommendation from one transmission shop. I have had the run around from the time I walk in the door at both transmission shops, neither one said there was any code stored or showing at the time. The electrical shop said they are able to communicate with the transmission and have found it is a "low pressure issue" but with so many different ideas said I am lost and looking for a long shot. I have changed the TCM and it was flashed as well. I have also changed the fluid, internal and external filters and checked all wiring connections. I have always kept the maintenance up on this truck and drove it easy. I have a PPE programmer on it, 5" exhaust and air raid intake. I know some of this information is not needed but just want any help I can get to get my truck working again. Thanks for any help provided!

 

[Mike L.]

Need codes. Also, is the trans stock or built? How much power are you running and for how long?. How many miles? All the info you posted means nothing. Pressure cannot be read with a scanner.

 

[Budneeds2beers]

Ignition switch? I got lucky with that.

 

[Crump]

Stock transmission
Stock power other than what the PPE Standard programmer adds
Miles 276k
As far as his findings on the pressure issue not sure if he used a scanner or checked line pressure to determine this.
I have also changed the ignition switch (forgot to mention)

When I changed the fluid the first time the fluid was just like new, no clutch material, not discoloration to it, etc

When I put a slight idle on the truck it will come in to gear as I let it roll, I have only done this getting it to the shops. When driving it will shift just the way it should with smooth shifting, no banging and it will shift from 1-6 and back down, but when you park the truck or put ir reverse it will display the error again. I can also start off in 2nd gear to move the truck usually with no issues, but like I said I have the truck parked and have not tried to drive it due to risk of harming it farther.
Thanks for your response guys!

 

[Mike L.]

Sounds like your trans is toast.

 

[Crump]

So an update to my truck issue I am having, the transmission shop that I have taken it to has finally found a code P0877. The replaced the wiring harness inside of the transmission due to it leaking fluid passed the connection and the pressure switch on the valve body. The tech that I spoke with said he is at a lost and does not understand why the code will not reset after replacing the switch and the harness. I just picked the truck up and could not be more lost as of where to go from here as this has been going on for almost two months now. When I was driving home the truck has the check engine light on and is stuck in third gear, it will not shift up or down. Like I have said I am lost and greatly appreciate any help anyone has to offer me. Thanks!

 

[Tothemax]

well they could take the pan back down. unbolt the pressure switch with the key on engine off use a scan tool to display the pressure switch reading use a pencil eraser to push on each one of the switches. if they all changed states then the problem is mechanical to the transmission

 

[juddski88]

I don't think I know of any shops in Kansas, but Husker Diesel is up in Nebraska and Full Pull Diesel Performance is down in Oklahoma City. Or if you are closer to Colorado, there are a whole bunch of decent shops around Denver.

 

[Crump]

I have attached some paper work that was provided to me by the shop as they were doing their trouble shooting.

 

[Crump]

I think I have had the worst luck with transmission shops in my city.