GM Pickup,Burb, Avy owners

We bought a 2007 Chevy Avalanche last fall.

Love the little truck...but it has had some issues of late that had me pulling my hair out.

Rig started giving me a Stabilitrak warning lamp....Stabilitrak off...Traction control off message pops up in the Driver information center (DIC)

Then the SES lamp pops on...

I grab my scan tool and take a peek..... Nothing real outrageous jumped off the screen.
Codes P0172/P0175 (Rich both banks)

Hmmmmm
Has to be a simple issue to cause both banks to go rich (Not a single injector or major mechanical problem)

The likely culprits were Purge solenoid and or MAF sensor

Replaced the MAF as the rig has 135K on the clock

Nope...same LTFT readings...(LONG TERM FUEL TRIMS)

Get to snooping through the scanner screen listings and find "Alcohol fuel %" at 66.7%

This truck is an E85 truck

We don't have E85 here.
I buy all my fuel at the same place (Pacific pride card lock)

I did some research on the Alcohol % error
Found lots of posts on it online..

Nobody seems to know why these things get a hicup and read the outrageous alky levels.

The alky requires more fuel to burn correctly. and when there is an error in reading the % of alky the ECM bumps up the fuel trim and then the O2 sensors see RICH (Because its plain gas in the tank) and then the LTFT are messed up (mine were -30 and should be down under -15 ...closer to zero is nice but this world is not perfect)

The codes set...light comes on and the stabilitrac message comes on...tanny shifts hard....very annoying.

My scan tool will not change things, only look at things and turn the lamp off.

I took the rig to the dealer here locally (Known the service manager for years)
We chatted about an hour and he called up one of his techs.

Yesssss..the alcohol % issue is the culprit.

The tech grabbed his Tech 2 and took a peek...his tool agreed with what I found.

He reset the fuel trims and set the alcohol % back to 10% (We use E10 in winter)

Rig runs sweet and so far all is happy with the little beast.

IF YOU HAVE A GM that's popping stabilitrak message and giving the ding ding ding

Any time there is an error (DTC...SES) the Stab trak message will happen. and the unit will shut off, tranny will shift hard.

The Stab trak system is interconnected with so many systems that any errors will shut it down.

The issue is that under some situations the Stab trak system could take control away from the driver and it could get ugly.. (BOEING 737 MAX SCENARIO) Well not quite that bad, but serious none the less..)

So GM designed the system to shut itself off if any errors pop up.

It will not tell you what is wrong...must be scanned and the error fixed.

I have been looking at a TECH2 knockoff (China) and the dealership told me they have several and only 2 real ones that they use for programming updates where its paramount that the tool will connect with MA GENERALS DATA BASE

Anyone use or have used/own a tech2 clone tool????

Hope this post can enlighten anyone with the later GM rigs (Fords and Dodges have their issues too)

 

I use HPTuners... each have their benefits

 

MasterMech

 

I've been away from the GM garage for 7 years... have never used a clone.

 

Wondering if your GM guy actually scanned the EBTCM where codes pertaining to those lights would be stored. Or you're 100% confident the PCM codes tripped those lights also???

 

Found the info in the diagnosis for a p0172/175 you're spot on. Here it is...



Important: Disregard any transmission symptoms, antilock brake system (ABS) indicators, and traction control system (TCS) indicators until any fuel trim faults are repaired. A fuel trim fault may cause default actions such as harsh shifts and illumination of the ABS/TCS indicators.

For E85 compatible engines only—Over estimation of the ethanol content will result in a rich shift of fuel trim values, and under estimation will result in a lean shift of fuel trim values. A fuel trim DTC may set if the learned alcohol content, Fuel Alcohol Content parameter on the scan tool, is different than the measured alcohol content in the vehicle such that the fuel trim values exceed failure threshold values.

 

Let us know if you pick up the clone. The tech2 is a hell of a tool.

 

I got to see a clone is action... they will do everything a genuine one will do EXCEPT ...THEY WILL NOT INTERFACE WITH GM to update the software from MA GENERAL.

No serial number that matches what GM has in their data base.

They will do all the stuff as far as reading and diagnosing, will reset fuel trims, and a host of other stuff.
Will access all the modules, plus ABS, Traction control, Stabilitrac.

It will even tell you about a faulty switch for a power door lock... I watched that happen.
Our Avy has a messed up switch on the driver side rear door.

The Tech 2 is $3500 and up.....

I can't suck up to that one.... $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

Most of us that work on our own rigs get by with far less, but the Avy is just too complex to make do with a mediocre scanner...I need bidirectional ability to change settings, resets and such, plus chassis module scans, ABS, Stab trak and much more than my AX7000 CAN DO

TOYS......

I found this one
US$224.00 GM Tech2 GM Scanner CANdi & TIS (Works for GM/SAAB/OPEL/SUZUKI/ISUZU/Holden) on Sale


Real close to tripping the hammer on this bad boy...

 

Once we got the Alcohol number back down out of the ozones the fuel LTFT squared away and things are sweet.

Still not sure why the thing over estimated the alky content.

I found the battery dead a week or so ago.
New battery, battery out for maybe half hour.
Ran the rig twice and then it sat for about a week.

Drove to town, shopped and then stopped off at the card lock and fueled up with regular E10
Drove only 4 miles home after refill and let sit for a few days.

Maybe the drive time after refill was the issue.
GM says 7 miles minimum ??????????????????


I will refill again here in another week or so.

May have been a glitch too..

It is not unheard of though.

Had the rig since September and not a peep.

Then it goes hen house.

Got about 50 miles on it since reset and it seems fine.

WE SHALL SEE.

 

Now this is something that smoke show will be able to help you with!!

 

The last Snap on scan tool we bought at the garage I worked at was over $7000. Bi directional and had some programming functions. Would reset fuel trims and such, however balked at many new key fobs. Snowy I would think your going to be good to go after 59 miles and your monitors are set. Dead batteries and replacement of batteries can cause weird unexplained things to go on in some modules.

Doggy

 

We know for sure it isn't Ford

 

This is the newest rig we have had to date THAT I HAVE MESSED WITH.

The 2017 Benz 300 4 matic was new and on a lease.
Never had any issues.

The other two beaters around here are a 1995 Burb 4x4 (OBD 1) and a 1997 Astro van which is OBD 2

The van is simple to work on...my AX7000 scanner will tell me anything I need to know and plain old tools will suffice to gitterdone.

The 2007 Avalanche is a whole new realm for this old "WENCH"

Without magic box tools it's certainly a no go.

Yessssssssssss....battery changes can cause issues.

Never had any in the past, but never had this much electronics on a rig.

After I changed the battery I stumbled across a blog that mentioned using a little gizmo to keep the system powered up to prevent issues

There is supposed to be a sticker on the rig near the battery..... well it must have gone AWOL....

 

Had to read this several times,my fault. You might be able to change the "paremitors" of the Map programming,for a short period of time. To change the programming of the engine/drivetrain, a "reflash of the computer is required. Just pushing a few buttons on a scan tool will not do this.

 

In my case the alcohol content of the fuel had gone whackey and was showing 67%
This likely happened during the battery change (I did not plug in a battery tender to keep some data)

The dealership tech agreed with my take on the issue as he had seen it before on the Flex Fuel trucks.

He changed the settings back to 10% (Normal for here) and reset the fuel maps to allow the computer to reset them to what they should be.

I have checked things a couple times since we fooled with it and they seem to be stable now....and where they should be..

I am told that this error is not all that uncommon on the alky burners.

Poor design as far as I'm concerned.

The benefits of using the alky are very minimal at best... uses more fuel, cost more per gallon and adds more electronics to go south.

Use the corn for cow food or good booze

 

You are daed on with the Alky comments , wasn't worth squat in the 1930's ain't no better now. Only time alky was any good was in those Offenhausers used on the 1/4 mile dirt tracks and that was straight alky.