I need some help with from people smarter than me. I have been searching the entire day but most if the issues I've come across are related to mismatched controllers and pedals/TAC modules.

In my case, I purchased the entire LS376/525 controller kit (harness, E67 ECM, pedal, etc.) from my local GM dealer and now all of sudden I have a "dead" pedal. I will admit that I had my local tuner update the factory GM tune to account for the bigger heads/cam/injectors, but, the car was running great up until last week. I have swapped the throttle body (and did the relearn process), and I have swapped the pedal but nothing has worked. The problem I am having is when I turn the key on, I can hear the fuel pump prime and the TB "adjust" and if I push the accelerator pedal down I can hear the TB blade opening and closing. However, after a few seconds, I lose all signal to the TB and my computer throws a P0606 code. I can watch the APP1 and APP2 sensor traffic on my scanner and I see all of the voltages scale appropriately and out of nowhere the accelerator pedal position drops to 0 and the ECM throws the code. I can clear the code and repeat the process and the exact same thing happens. The engine will start and idle just fine but as soon as I give it gas, it stumbles and immediately throws the 0606 code.

From the research I have done, the E67 controller has multiple tables and when it gets reflashed from tuning software, only a small portion of the tables get modified but the majority of the base GM programming stays in place. I don't have a copy of the tune that was loaded but I can't imagine the reflash caused the issue since it was running just fine for the past year. I have checked all of my fuses and there are no broken wires causing a continuity issue.

My main question is do I have to replace the ECM? My local dealer is pretty much useless since there is no VIN associated with the controller. I've read updating the software in the ECM could fix it but is it possible to send it somewhere to get reflashed with the base OS from GM? I'm not happy about buying a new controller but I will if I have to. I would obviously like to run through all of the free options first.

 

Have you checked all connections and grounds? There might be a loose plug or pin you might have missed

 

Short answer...sort of.

It's a completely unmolested connect and cruise harness with the ground lugs on the back of the heads and the ignition and power input to the fuse box. I've got heavy gauge ground straps from the engine to the frame and the body to the frame on both sides of the engine, and the battery is grounded directly to the frame. I know bad grounds can cause a lot weird issues but this a very specific problem and everything else works like it's supposed to. However, since the only thing in common that I haven't replaced is the harness and ECM, I am going to spend the day tomorrow inspecting the harness and testing connectivity from the pedal to the computer and the throttle body.

 

I was able to check continuity across the harness from the pedal to the controller to the throttle body. All 5v references are valid and all grounds are secure. I heard back from my tuner and he told me his experience has shown the P0606 code means the ECM is bad. Especially since everything was working and then it stopped working. If something was wrong out of the box, we would've been fighting it from day 1. I'm not happy about having to spend $500 dollars for a new controller. Part of me thinks it would have been easier to get everything from a donor car instead of using the GM kit. At least I would have VIN to tie everything to that way.