Originally Posted by
DmaxMaverick
OK. I got access to the service manual. DTC P106C is a ghost. It doesn't exist in the real world. You were correct replacing the GPC for the GP failure repeat, exactly what the manual suggests. The bad news is, if the PCM complains after a GPC replacement (such as a recurring code that won't clear), you must use a Tech II to run the fuel injector flow rate program, so the PCM and GPCM can adjust GP voltage for individual cylinders (I think it isn't really that, but the module needs to "pair" with the PCM). The manual doesn't state what happens when it's needed and you don't, so now we know. Either tolerate the MIL (it may clear itself, eventually), or pony up for some shop time. It shouldn't effect drivability in any way, so there's no hurry. One other interesting thing I noticed is, only the OEM replacement controller module shows a statement suggesting any programming. None of the aftermarket controllers do. Not sure what it means, but all the controllers I replaced before were aftermarket.