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Gary
Gary, ASE Certified Technician
Category: Chevy
Satisfied Customers: 743
Experience:  Senior Technician
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I am having a problem with my 2007 Avalanche. Service

Customer Question

I am having a problem with my 2007 Avalanche. Service stabiltrak and service traction control lights and are on and SES light is blinking, engine running rough. Shifts hard. It was intermittent but now the problem is ongoing. Cannot drive it in this condition.
Submitted: 4 months ago.
Category: Chevy
Expert:  mike switzer replied 4 months ago.

when the check engine light is blinking that means you have a catalyst damaging misfire. if you have changed all the plugs and wires you are getting to much fuel. do you have access to a scanner?

Customer: replied 4 months ago.
I scanned and only got P0300 Misfire. The problem has to do with the Stabilitrak warning. Whenever the Service Stabilitrak and Service traction control lights disappeared in the past, the blinking check engine light also went out and the idle was no longer rough and all was normal.
Customer: replied 4 months ago.
This is a well known problem on the
avalanche and 90% of the time it was a bad throttle body or throttle body sensor. I replaced both but that did not solve the problem
Expert:  mike switzer replied 4 months ago.

it is a well known problem on a lot of gm v8s. question what kind of air filter do you have?

Expert:  mike switzer replied 4 months ago.

and as far as the scanner goes i was asking if you have access to one that can read data. not so much the codes. a po300 tells you pretty much nothing.

Expert:  mike switzer replied 4 months ago.

the most common issue with gm vehicles and the v8's is the mass air flow sensor going bad. a bad mass airflow sensor can cause poor shift quality and misfires. also a lot of people use k and n air filters and the oil in those filters can damage the sensor itself.

Customer: replied 4 months ago.
I don't have access to a scanner that reads more than codes. We took it to the Chevy dealer last week and the mechanic charged us $100 to diag it. He said they would start by changing the spark plugs and pop plug wires and the ignition coil at the #7 cylinder and then would address the stabilitrak problem afterwards. They wanted $500 to change the plugs, wires and 1 coil. I did it all myself for about $150. His reason for the #7 coil was because they got a misfire on #7. After changing that coil its now a p0300 generic misfire. I need to find out what is causing the stabilitrak/traction control problem. That is what's causing the misfire. Because whenever the stabilitrak/traction control issues disappear, so dies the miss fire code and it no longer idles rough or shifts hard in first and second gear. This problem all began shortly after my gf hit a curb pretty hard. Not sure if this caused thr problem or if its just coincidental.
Expert:  mike switzer replied 4 months ago.

i understand a bad mass airflow will cause poor shifting in the transmission. and whenever the tansmission has harsh shifting or an issue the computer sees it will set the stabilitrack light. the 4l60e transmission in those trucks are not as reliable as they should be either. i work in a transmission shop and have literally changed 5 in one week. i would say that is our most commonly replaced transmission. but i would start with the mass airflow and a standard air filter (if you have a K+N)

Customer: replied 4 months ago.
I will head to autozone tomorrow and see what their scan shows. If it shows nothing other than p0300, I will buy a new maf sensor and see if that takes care of the problem.
Expert:  mike switzer replied 4 months ago.

make sure it is not a duralast brand maf sensor but something such as acdelco or other reputable brands. also no airtex. 99.9% of airtex products are bad.

Customer: replied 4 months ago.
OK. Autozone pulled up the same P0300 code which as we know is worthless so I decided to roll the dice on the non-returnable maf sensor. They had to order the maf sensor and it will be in tomorrow (Thursday). Hope this is the fix.
Expert:  mike switzer replied 4 months ago.

this is a common issue on these vehicles the only other issue that could be causing this if it is not the MAF is the ignition switch.

Customer: replied 4 months ago.
Ok I just spent another $100 on an acdelco maf SNF still have the same problem. In fact it idles even rougher now and now has 7 codes which are: P0300 Random Missfire Detected, P0068 MAP/MAF -Throttle Position Correlation (appears twice on scanner), P0102 Mass Volume Air Flow Circuit Low Input, P0107 Manifold Absolute Pressure/BARO Sensor Low Input, P0113 Intake Air Temperature Sensor 1 Circuit High Input, P0300 Random Missfire Detected (displayed again). So discouraging! Air Filter is new. I really hoped that replacing the MAF sensor would be the cure. I'm going broke on this vehicle and have owned it for less than 3 mos. What now?
Expert:  mike switzer replied 4 months ago.

sounds like the vehicle was started with the maf sensor unplugged with that many codes. also have you reset the keep alive memory with the scan tool after connecting the new maf sensor?

Customer: replied 4 months ago.
I plugged in the new maf sensor before starting the truck. Then I reset the codes with my scanner. Now its reading only the P0300 Random Missfire and still has the same Service Stabilitrak and Service Traction Control warnings with flashing check engine light and runs rough. I also disconnected the battery cables for 25 minutes and reconnected hoping to clear the ecm but no luck. Not sure where to go from here.
Expert:  mike switzer replied 4 months ago.

ok do you have the ability to access the underside of the vehicle? to access the transmission plug? it is on the passenger side behind and exhaust shield. the shield is held on with two bolts which have a 10mm head.

Customer: replied 4 months ago.
I can probably put it on jack stands and access the trans plug. What should I do once I access it? Also, should I no longer consider the ignition switch as the cause? You mentioned earlier that if its not the maf sensor, it has to be the ignition switch.
Customer: replied 4 months ago.
Ok we just had a friend put it on an expensive diag scan machine and it brought up multiple codes. Hopefully this will help you to diag the problem. Here are the codes:B1325
B1000
B2635
B1640
B1023
B1440
C0899
C0561
C0242
P2544
U0140
U0073
U0155Please let me know if this helps.
Expert:  Gary replied 4 months ago.

Hello there,

Did you perform an idle learn after you replaced the throttle body?

You have a few codes to do with low volts and no comms.

Can you clear them all and we'll start again.

Gary

Customer: replied 4 months ago.
I no longer have access to rescanning the codes as my friend just left for vacation. The low voltage was because of the battery being almost dead from leaving the door open while scanning it. Are the other codes significant? I did not perform an idle learn. Is this something I can do myself? I'm thinking at this point that I should just take it back to the Chevy dealer and have them fix it.
Expert:  Gary replied 4 months ago.

You need a GM scan tool, many scanners don't do the functions necessary.

Idle learn is a GM scan tool function.

It would be wise to take it to the dealer.

The misfire is the root cause, the ESP and traction control warning lights are disabled and light up as a result. Not the other way as some might think.

I hope this helps you.

Kind regards

Gary

Customer: replied 4 months ago.
Thanks Gary. I will take your advice and take it to the dealer.
Expert:  Gary replied 4 months ago.

Wishing you well, and hope the dealer will sort it for you.

Kind regards

Gary