GM Watching Your ECM

**rmchowchow** · 05-20-2008, 19:38

Good evening, this is my first post, but I read all the time on here. I was wanting to put a programmer (think i am saying this write) in my 08 GMC 2500. I tow a 35' 5th wheel and I am only trying to improve my MPG. I get 14-15 around town, 19-20 highway, and 9.5-10 towing (I have been playing with different driving techniques and additives that is the best towing. One thing i did find out by mistake, do not tow with out being in tow mode, MPG went to under 8). Anyways I was at my dealer last week, they sell a couple of brands, and asked them about warranty issues. The service manager informed me that about 30 days ago GM issued a bulliten, that for any driveability problems that you bring your vehicle in for, they are requried to check your ECM for software changes. He also told me that they have hidden a number in their, so even if you swap your program in and out, they can tell. Once that number shows a change, your warranty is done. Is this true? And if so any suggestions? I am going to AR in June with the camper, and of course would like to help my cost.

Thanks in advance,
Bob

**Duramaster** · 05-20-2008, 20:19

Yeah it's true. I had an emerging issue course that more or less said that the LMM DMAX Diesel ECM's will actually keep track of the last 10 ECM software reflash P/N. Anyway, hopefully that turns out to be a good thing for people like me!

**Kennedy** · 05-21-2008, 05:32

This is purely speculation, but the LBZ shares the same ECM and likely the same logging.

My solution is to do my Custom tuning on a core ECM and leave the stock ECM bone stock.

**nomad03** · 06-04-2008, 18:04

His is my first time posting on this page I am A big time reader. I use a super Chip progamer. will this change the number in the ECM?

NOMAND

07.5 2500crewcab 4X4

**AKMark** · 06-05-2008, 04:31

Yes, when you use a programmer, you modify your ECM. It logs it and they can verify that if they check it.

GM isn't the only company doing this. Neighbor has a blown Mazda 3 that he changed the tuning on and it backfired, now looking at $5200 to repair, and warranty will not cover because he modified the computer. I know of two others that are also having issues with warranty, but don't remember offhand what they are driving.

**chipper** · 06-06-2008, 13:23

Originally Posted by rmchowchow

Good evening, this is my first post, but I read all the time on here. I was wanting to put a programmer (think i am saying this write) in my 08 GMC 2500. I tow a 35' 5th wheel and I am only trying to improve my MPG. I get 14-15 around town, 19-20 highway, and 9.5-10 towing (I have been playing with different driving techniques and additives that is the best towing. One thing i did find out by mistake, do not tow with out being in tow mode, MPG went to under 8). Anyways I was at my dealer last week, they sell a couple of brands, and asked them about warranty issues. The service manager informed me that about 30 days ago GM issued a bulliten, that for any driveability problems that you bring your vehicle in for, they are requried to check your ECM for software changes. He also told me that they have hidden a number in their, so even if you swap your program in and out, they can tell. Once that number shows a change, your warranty is done. Is this true? And if so any suggestions? I am going to AR in June with the camper, and of course would like to help my cost.

Thanks in advance,
Bob

Bob,
I cant understand why you want to mess with it. You are doing as good or better than most on your fuel mileage, so why risk warranty problems?

**gillguy** · 06-07-2008, 09:52

Originally Posted by chipper

Bob,
I cant understand why you want to mess with it. You are doing as good or better than most on your fuel mileage, so why risk warranty problems?

X2. That's about what I get.

**Tractorhauler** · 07-04-2008, 04:47

Kevin,

Will there be any problems with the Exhaust Particulate System with your Custom Tune? Any Flashes come up, any plugging problems? I am more interested in the Economy/Tow upgrade.

Thanks,

Mark

**Mark Rinker** · 07-05-2008, 06:28

Originally Posted by rmchowchow

...Anyways I was at my dealer last week, they sell a couple of brands, and asked them about warranty issues. The service manager informed me that about 30 days ago GM issued a bulliten, that for any driveability problems that you bring your vehicle in for, they are requried to check your ECM for software changes...

Sounds like a major problem of the left hand not communicating with the right hand. They'd better be prepared to stand behind any 3rd party tuner that their Parts Department is selling...keep your receipt handy!!!

The ECM swap (Kennedy Diesel approach) is 5-minute easy and trouble free for dealer visits. Unless they start dusting the ECM for fingerprints, I am not worried.

**Kennedy** · 07-05-2008, 13:19

Originally Posted by Tractorhauler

Kevin,

Will there be any problems with the Exhaust Particulate System with your Custom Tune? Any Flashes come up, any plugging problems? I am more interested in the Economy/Tow upgrade.

Thanks,

Mark

There are a lot of plugging/regen problems with totally stock trucks. A lot depends on fuel quality, idle time, driving style etc. The same will hold true for my tuning. All I can say for sure is YMMV (your mileage may vary) as I try to tune to the clean side with any tune. Most of my customers started out with problems/hassle with their vehicle systems. Some started out clean and still wanted to upgrade. So far the feedback has been excellent on all counts with the exception of an occasional rogue DTC that is easily corrected.

**OhmEye** · 05-07-2009, 23:47

Would a plug-in module like Edge Juice leave remnants in the ECM?

**Mark Rinker** · 05-08-2009, 05:39

No - it restores your original programming (backup) and overwrites its image.

**DmaxMaverick** · 05-08-2009, 08:40

Most all programmers and boxes restore the original calibration once removed and/or deprogrammed. The last word we had in this discussion was the breadcrumb trail, and not necessarily the program itself, is the indicator of power adding programmer usage. Later model PCM's (2006+), it was claimed, count the number of EEPROM/NVRAM writes, regardless of how it writes/rewrites. As far as we could tell, there is no indication of this prior to 2006 models. There was also some speculation of a checksum counter as part of the startup diagnostic process (still, with the 2006+ models), which could leave an indicator there was a change to the PCM programming at some time.

**OhmEye** · 05-08-2009, 09:05

Well that's good news for my unit. I might live my life in a manner hell-bent on offending the Washington and Sacramento types, but somehow I feel like I want to keep the folks in Detroit happy if I can.

**gimpyhauler** · 06-24-2011, 11:21

This doesn't really effect me. I have an '07 Classic LB/CC with 166,000+ miles. I like what my Bully Dog does for my widdle twuck.

**EdHale** · 06-25-2011, 03:55

The best solution to poor towing mpg is to slow down. I tow a 35' 5th wheel also and I consistently get 12-12.8 mpg. I tow at 55 mph.

Thread: GM Watching Your ECM

Thread Tools

Display

GM Watching Your ECM

Gm Watching ECM

Kennedy tune with core ECM

Posting Permissions