Hello - New to the forum and have a question regarding my 07 Yukon 5.3L and dealership flashing process.

I've been to the local GMC dealership to have my PCM (ECM & TCM) flashed in order to reinstall a Diablo tuner. The first two times they incorrectly flashed just the ECM. Then the Diablo wouldn't install the transmission tune.

Went back to get both ECM & TCM flashed. First time the tuner again failed to load, citing transmission issue. I returned the tuner to Diablo and they tested it, finding that it worked correctly.

Two days ago I returned to the dealer and again paid them to flash both control modules. They assured me that it was done. I knew when I left that it was not because the Yukon wouldn't go into DOD 4-cylinder mode. Sure enough, when I tried to load the Diablo it said there was a Diablo tune installed on the vehicle and stopped. It is supposed to save the GM tune before loading their tune. However, if it doesn't detect a GM tune it won't load.

I called the service writer and was basically blown off, saying that the tech assured him it was installed. I asked why it wouldn't go into 4-cylinder mode if the GM tune was flashed. He said he couldn't help any further. I contacted the gen mgr and am waiting for his reply - 2 days.

My question is this: If the GM equipment flashes a GM tune on the ECM and TCM, doesn't it indicate if the flash was actually installed? I cannot imagine that they would have equipment that doesn't tell them if it installed correctly. Otherwise, just wave a magic wand over the engine and say ' it'* done'.

Anybody have any idea about whether they can actually detect a correctly installed flash? Or is this a case of a technician not knowing what to do in the installation process?

Thanks for any help/advice.

Mike

Cmon man, you already have this posted somewhere else. Nobody replying to it is probably a good indication that nobody has an answer.

Mike:

Sorry to bother you with my persistence. It'* a trait I learned early and it'* served me well over the years. I actually learn more that way. Sorry it conflicts with your world view.

I incorrectly assumed you might know more than the previous forum. As they say, never assume, because it makes an *** of u and me. You're the great SENIOR ADMINISTRATOR, so please....bounce me. Won't hurt my feelings at all. I'll have forgotten you by the time this page closes.

Where else is this posted?

I am curious what Tech II has to say on this subject...

Rjolly - I think I may have posted it here previously - yesterday. I looked for a confirmation but didn't see one. So I figured I had done something incorrect in posting. I did look into another GMC Yukon Tahoe site but didn't see any indication of interest in tuners and flashing. That'* why I tried here. Never know where the expertise lies. I just want to know if the dealership tech is doing it properly and if his equipment confirms or doesn't confirm that the GM programming has loaded and erased the tuner programming. I figured I might run across a tech who knew how the equipment they use operates.

Mike: I apologize. I misread your comment and thought you were referring to me posting on another site. As I thought, I realized that I had tried posting the same question here yesterday but didn't find it today. That'* why I posted today. My mistake for overreacting.

If there is any doubt about the programming, why in the world do you go back to the same GM garage?

Any GM garage can program a module, even one that doesn't sell Yukons....

If you go to another garage, and they have a Tech that knows how to use a Tech II or MDI, and does program it right, then you have a leg to stand on, to go back to the other garage, to request your money back, for improper programming....

Tech II:

Thanks for the info. It does seem dumb to have given the local GM dealership 4 tries, but I actually went to a second one after first two fails.

As directed by the Diablo tuner, I told them I needed the PCM flashed. However, from 2007 on, GM uses an ECM (engine control module) and TCM (transmission) instead of a PCM (powertrain). It appears that the second dealership only flashed the engine control module. The referenced the "PCM" and gave me both the old and new numbers for the flash. The Diablo again wouldn't install - transmission error.

Called Diablo and they clarified that I needed both ECM and TCM flashed. That'* what took me back to the local for a third time. Requested both.

Diablo tune failed to install again. Talking to Diablo, I'm thinking the tuner is bad. Sent it in and they tested it on two vehicles there. No problems.

Back to dealership for a transmission control module flash before installing the Diablo tune. I notice when driving home that it wouldn't go into 4-cylinder deactivation mode. I knew the flash didn't change the previous Diablo tune and it wouldn't install again.

That'* when I called and talked with the general manager, asking the same question I asked here. That was earlier this week. Had a service quality follow-up phone call and I brought her into the situation. She promised to talk with him and get back. So far nothing.

My primary goal was to know whether the GM flashing equipment/program would give a 'yes' or 'no' as to whether the flash was actually installed. If 'yes' then there'* a fault in their process or in the vehicle itself. It 'no' then they should have advised me that it failed to install.

I really wanted to know that answer before I speak with the Gen Mgr again.

By the way, did speak with two other GM dealerships. I live in a rural area and, other than the local, they're 30-60 miles away. One said they charge two hours of labor to do the flash, or $230.

The other service rep said he was familiar with issues related to tuner programs. He said they can block the GM tune from installing. That sounds plausible, and brings me to where I am today.

That'* more than you want to know about this, but I wanted to give some background for a strange question.

Thanks again,

Well, it certainly doesn't take two hours to flash two modules....if you know what you are doing....

I would ask Diablo what are the flash numbers needed for the modules, and I would want to know from the GM dealer, what are the flash numbers for each module, that were installed.

Thanks for the tip on the flash numbers. That should help clarify what they've done (or not done). I'll contact Diablo'* tech support. I didn't know what to ask them before and it was like shooting in the dark.

I thought the 2 hour minimum charge was bs too. Maybe because they're the ONLY GM dealership in Panama City, FL.

Enjoy the day.