Looking for thoughts on P0606 for a 2008 Buick Allure / LaCrosse with a 3.8 V6

Hello all,

With regards to trouble shooting a circuit, ScannerDanner teachings are (and the words to follow is my wording) "identify the type of circuit you are working with first (for example - a pull up or pull down circuit / switch) so that you understand the circuit and then go eliminate whether or not you are dealing with an open circuit, short to power, short to ground, excessive resistance, voltage induction, bad component, and/or module communication issue". All of these scenarios deal with wiring out side of a module/computer.

Today, a 2008 Buick Allure / LaCrosse came into the shop with a P0606 - Engine Control Module Internal Performance. In an effort to speed up the diagnostics, could I be as bold to say "well, this is an internal issue within the PCM and thus no external wiring checks are needed - the PCM needs to be replaced"?

Thoughts appreciated and thanks in advance.

Robert

IMO, no, the code by itself is not enough evidence to call a PCM. Too many variables.

In an ideal world? Sure, the PCM should be able to make that judgement about itself. But we all know codes can't be taken at face value. :silly: Or shouldn't be, anyway. Realistically, there are a whole host of wiring problems and in-range failures that can fool the PCM into condemning itself.

If it's a hard code, then the PCM powers and grounds would be load tested. 5V verified. An intermittent issue gets harder.

Yeah, I didn't think about the rest of computer needing good information from other external sources to help make good decisions while monitoring itself. Thanks for that point.

But because this is post is all about me (a little joke there.... hoping it was not misunderstood), I wanted to work with a narrow lens on this P0606 for the 2008 Buick Allure that is currently at the shop. Let me share with you the description of the P0606 as noted in AllData:

Before noting the description of the P0606, please note that this trouble code is grouped P0601, P0602, P0604, and P2610.

Here is the P0606 description (again, as per AllData)
"This diagnostic applies to interal microprocessor integrity conditions within the powertrain control module (PCM) and the throttle actuator control (TAC) system. This diagnostic also addresses if the PCM is not programmed.
The PCM monitors is ability to read and write to the memory. It also montiors a timing function. The PCM and the TAC processors are used to monitor the TAC system data. Both processors monitor the other processor's data to verify that the indicated accelerator pedal position (APP) calculation is correct. The PCM performs an intrusive test in order to confirm that the APP signals are not shorted together. The PCM accomplishes this by pulling the APP sensor 2 low momentarily and looking for sensor 1 to all be pulled low."

So here is what I struggle with - as per Tyler's point, confirm the wiring between the APP and the PCM is good. But once that is confirmed, I am not sure how to check the integrity of the two processors inside of the PCM being happy. If the wiring from the APP to PCM is good, then call the PCM?

Again, thoughts appreciated and thanks in advance.

Thanks for posting the code description. I'm at home, so I don't have access to SI. Much appreciated.

I admit, it's unlikely that an APP circuit problem would result in a P0606 and not an APP code. :silly: But, just to play it safe, I'd check the circuit anyway. The intrusive test they're talking about is directly observable on a scope, if you really want to see the magic happening.

As for the processors inside the PCM, that's their problem. As long as you've confirmed the PCM and the TAC processors have everything they need to do their jobs correctly, it's PCM time.

Thanks so much for taking a moment to address my post - really helped me to sort out "the stuff" in my mind regarding this P0606! Thanks again!