LBZ conversion in a 94 k2500 won't go over 1200 rpm

[94 Bro]

I'm lost here. I put a 2006 LBZ with the Allison 6 speed transmission and all the wiring harnesses and computers in a 94 K2500 (the TCM and PCM are from different vehicles though). I even included the dash and steering wheel even though the airbag was popped. The problems I'm having is when I shift into reverse, neutral, drive it has a very violent shift. I don't have the shift indicator at all and when driving forward it won't go over 1200 rpm. When in reverse it will go a little faster up to 1500 rpm. When in Park it will rev it's full range. When I go to start it the fuel gage seems to work and then it drops to empty and the light comes on. I have the cel on as well as the parking brake and abs. I am using the brake system from the 94 (which I think explains the parking brake and abs) but the gas pedal is from the 2006. I have not hooked up any wires to the brakes yet which I don't know if that could cause any problems yet. I have an AFE intake and I used the EFI live to get past the VATS but I have not loaded a tune yet. I changed the fuel filter as well. The codes I see with EFI Live is:

P0504- Brake switch circuit 1-2 correlation (I'm thinking because the brake electronics aren't hooked up yet)
P2068- fuel level sensor 2 circuit high voltage
U0101- lost communication with TCM (this one I get 5 times)

The last two won't clear either.

Can someone please help me fiqure this hard shifting and not being able to go over 1200 rpm. I done a lot of searching but I just cant figure it out. Is it one of the limp modes or communications or solenoids? Thanks,

 

[THEFERMANATOR]

Sounds like your CAN BUS isn't functioning properly. The TCM will need the brake switch inputs as well, but you have to get the communications fixed before you go any furthur.

 

[GeneralTJI]

Hope you get it figured out! Pics?!

I sometimes randomely get the U0100 lost comm. w/ TCM and it causes the trans to shift at higher rpms like t/h mode but also seems to shift w/o defuel That particular code doesn't cause a limp mode or fuel shutoff etc. though.

 

[94 Bro]

Is there a way to check signals or something with the can bus? Could the TCM be bad? I checked pin 9 and 69 for continuity and that is good but could it still be bad? I guess I will work on geting the brakes wired up and go from there. Could it be the nsbu switch or whatever it is called on the 6 speed?

 

[94 Bro]

Yeah me too, cause I'm going to have to move in a couple of months and I don't want to pay a shipper. As far as pics I do have some and I planned on taking a bunch but I found out I can't get much done when I'm taking pictures. I had a ok amount of time to do this but it snuck up on me. I'll figure out how to post pics and then I'll get them on here.

 

[THEFERMANATOR]

Can you talk to the TCM and read the cal file from it with EFILIVE? If not you have an issue there. Also are you SURE that teh TCM you are using has a compatible OS in it? There are a couple different ones for teh 6 speeds, and if you have the wrong one you will get a limp mode from it.

 

[94 Bro]

Thank you for your response. I tried pulling the cal file and EFI was displaying TCM not detected, status unknown, did not respond to seed request, TCM may not be secured. Then it goes through the 10 min deal and at the end it saves it as bad file format.tun and tells me to send that to efi live. I will do that shortly.

As far as the tcm being compatible, I don't know. I bought everything from someone else selling it as a conversion package. I do know that the tcm came from a different vin than the pcm. Do they need to be the same? Thanks again,

 

[THEFERMANATOR]

You need to set down and trace aout your CAN BUS wires from teh data link plug back to the BCM, ECM, AND TCM. I'm willing to bet you will find that the CAN BUS isn't connected to the TCM properly, OR you have a bad cal file in your TCM that isn't compatible with CAN BUS. This sounds more like a conversion problem though to me in teh wiring.

 

[94 Bro]

The wiring is stock for the 2006. It doesn't mean it's good, so I will check that. Is there a continuity check with the can bus wires?

 

[94 Bro]

You need to set down and trace aout your CAN BUS wires from teh data link plug back to the BCM, ECM, AND TCM. I'm willing to bet you will find that the CAN BUS isn't connected to the TCM properly, OR you have a bad cal file in your TCM that isn't compatible with CAN BUS. This sounds more like a conversion problem though to me in teh wiring.

I think your right. I'm working through the wires now and I have some pinout diagrams and will start testing. I got delayed alittle cause the Wife said I had to paint:whip: . But i had some time today and some things don't seem right like I think I'm missing wires from my diagnostic port. I was gonna have my tcm tested and flashed with the same vin as the pcm but the local dealer said they couldn't do it with out the whole truck, then they said they couldn't help me at all because it was a swap. I finally talked to a tech and he said that if I can't comunicate with the tcm than they can't flash it because they use the diagnostic port. He also said that since I'm not using the brake controller that I need to be sure there is no can bus wires going that way and if so figure out what to do with that. Hopefully tomorrow I can dig deep into tracing the wires.

Do you know of a way to make the transmission run as a stand alone? I read somewhere that it could be done but you would lose the tow haul mode. I don't really need that right now and would like to just get it running.

 

[2wd_Sled_Puller]

I beilve one of the companys out there have a stand alone controlled out for them. Or u can do it my way get the scematic and shift it with toungle switches

 

[94 Bro]

You need to set down and trace aout your CAN BUS wires from teh data link plug back to the BCM, ECM, AND TCM. I'm willing to bet you will find that the CAN BUS isn't connected to the TCM properly, OR you have a bad cal file in your TCM that isn't compatible with CAN BUS. This sounds more like a conversion problem though to me in teh wiring.

So I'm able to start on the truck again. I did a continuity check at the dlc, ecm, and tcm. For the gm+, I checked the wiring at pin 6 at dlc with 57 from ecm and 6 at the tcm and there is zero resistance. For gm-, I checked the wiring at pin 14 at dlc with 44 from ecm and 27 from tcm which has zero resistance. I checked and cleaned all the pins on both the tcm and ecm. So am I correct in thinking that unless the pins aren't making contact when the harness is plugged in, I should be able to communitcate with my tcm?

 

[wes06dmax]

is the mass air flow sensor hooded up it could be many things make sure you hook up all the sensors but the mass air flow would make mine do that everytime

 

[94 Bro]

is the mass air flow sensor hooded up it could be many things make sure you hook up all the sensors but the mass air flow would make mine do that everytime

Sorry, could you clarify what it would make yours do. Would it mess with the communications?

 

[wes06dmax]

the sensor that is in your air intake done it to mine for a good while until I figured it out

and then it done it again when I swapped my htt turbo back to a cheetha I dont know these lbz can do some wierd things but make sure that mass air flow sensor is correct in all ways