LS3 with E38 and T42 intermittant dead pedal issue

[truckfan2]

I have a short box chevy pickup that was swapped with a stock camaro LS3 and a 4L70E 17 pin transmission. It is running a PSI conversion harness with an 08 tahoe E38 ecm and T42 tcm. I swapped in 2wd transmission parameters and the truck drives and shifts well with the exception of a random dead pedal issue. You have to shut it off and restart it and it is fine again. It only happens once in a great while so I feel like I may have something off in the etc or maybe torque management parameters. I am running the camaro throttle body with a truck pedal. I can recreate it very rarely by having the key on and stabbing the gas quickly but not every time. I was not too worried about the random dead pedal as it doesnt happen often at all but now that I am trying to add the dakota digital dbw cruise system it happens anytime you try to set the cruise and dakota said its in the tune. Any help would be appreciated.Dave Lewis 10 camaro LS3 w 08 tahoe T42 2wd segment swapped final.hpt

[gtstorey]

My guess is the ECM/throttle body/ acceleration pedal mismatch. But let’s see what the more experienced people say.

[kevin87turbot]

Just scan it next time it happens and see what DTC's are current. That'll give you a direction to look.

[truckfan2]

Sounds good, I'll put the truck on stands and run it up to speed then try to set the cruise and see what I get while scanning it. We had a dam blizzard here so its stuck inside for at least a week or two until the crap clears off the roads.

[Alvin]

you really need to know the DTC it has when it goes into limp mode.

Throttle bodies do go bad.. I'm not saying you should change it but I wouldn't think immediately pedal/throttle body mismatch if it's been together for a while and this is a new issue.

[truckfan2]

It looks like the truck threw two codes when the cruise tried to engage killing the throttle. P0606 ECM/PCM processor and a P2138 throttle pedal position sensor. Any chance the camaro throttle body with the tahoe ecm, tcm, and pedal would cause intermittant issues? I would think if they are not right it would just kill the throttle all the time? I never was scanning it when it used to very rarely go dead pedal before I tried installing the cruise control but I would imagine its throwing similar if not the same codes. I'm not sure if I should be using part of the camaro etc settings with the tahoe tune or just all the tahoe stock settings?

[blindsquirrel]

Has the ECM ever been write-entired in HPT with a different OS, or segment swapped? P0606 is either a mismatch between the TAC segments (which HPT cannot access) and the rest of the ECM, or a bad ECM (hardware).

[truckfan2]

Has the ECM ever been write-entired in HPT with a different OS, or segment swapped? P0606 is either a mismatch between the TAC segments (which HPT cannot access) and the rest of the ECM, or a bad ECM (hardware).

As far as the ecm goes I have not swapped any os in it. It is still running the original 08 tahoe os. I changed the throttle rate map to the camaro map since I am running the LS3 throttle body which may have been causing the random dead pedal. I also changed the max throttle angle to 99% instead of 100 which I was told can cause an occasional 0606 error. I scanned the truck while trying to engage the dakota digital cruise and it is only throwing code 2138 now instantly when you try to set the cruise. I have not seen the dead pedal in any other situation yet since making those changes, only when you try to set the cruise control.

[blindsquirrel]

Put all the ETC stuff back to stock.

[truckfan2]

Got it.....Wired the dakota digital ground source to the GM dbw pedal ground purple wire and that got rid of any 0606 codes. I then ran the vss signal off the ecm speedo output instead of the vss sensor directly and all is good now. Thanks for the input.