Got my plugs and a general tune-up done today and while they were doing the tune-up, they tried to scan the truck for any trouble codes. They said they were unable to communicate with the PCM due to the PCM locking them out or something.... The dealer concluded that the truck was chipped (which was a surprise to me).
I find that odd because the original owner was a contractor and used the truck for work purposes... It DOES have a trailer brake controller in it so one could potentially conclude that the PO put some sort of trailer towing custom tune on it because the truck doesn't seem at all like it is chipped or running a custom tune (way slower than my stock 6.0L denali was).

So, that being said, what is the likelihood
a) of returning the truck to stock configuration until I get a programmer (not that I would do that as the truck runs great as-is, however I would assume the dealer has to just basically "reset" the PCM?)
b)Me being locked out of reprogramming the PCM when I buy a programmer (looking to get one after Christmas) just like the dealer is
c) Could the PO be "covering up" problems with the truck using this custom tune or whatever it is?

That's basically all the info I have on hand right now.... I guess I could also phone the PO and ask him about a chip or programmer that he used??

Thanks

 

Id call him up and ask them on the other hand these trucks are slow compared to GMs 6.0 even the 5.3

 

Option "c" doesn't seem too likely, but I've heard weirder stuff.

To start, are you comfortable that the dealer really knows what they're doing? They could have slacked off and not done the scan at all, then made up a story. Were they able to read the CM info to do the tune up? If they could do that, I'm not sure you have a problem. If you're comfortable with the dealer, then next steps are tough.

If the truck is chipped, then you need to figure out what kind was used. Some of them just plug in between the computer and the truck and you can just pull them out to restore factory. I've heard that others actually replace the factory components, so pulling them isn't a solution.

If it really is "chipped", then you can't do A or B. Call the PO. If that doesn't work, go to a local garage and ask them to read your codes. Should be cheap and interesting to see what they say.

You're asking the right questions. Hope you get some answers.

 

Any Autowrong or O'reillys will scan your comp for codes for free.

 

That's odd, maybe something goofy with oem scanners. If you ever need service on it take it to a private shop with a good rep. Any snap on or OTC can read even with a custom tune.

 

I am not too worried about getting any codes read as I have an ultragage that could do that.
Where should I start looking for this chip? I will probably give the PO a call tonight and see what he says, but if he doesn't know anything about it, I am back to square 1.

I am pretty sure the dealer I go to knows what they are doing as I have been doing business with them for a long time and trust them.

Thanks

 

If you had a CHIP installed...it would be inserted into the OBDII port...where they were attempting to talk to your trucks computer...maybe they had no power at the port due to a blown fuse....

 

That's what I was thinking too.

I had the same issue if no communication but when started testing there was no power. Sure enough blown fuse. My question then was why did the fuse blow. Still no answer on that.

 

Okay well I know for a fact I do have power at the OBD II because my ultragage runs off that. So must be a custom tune then

 

you should stiil be able to comunicate with it regardless