Service Traction and ESC

triplex-08 said:

if the service traction control light is on, or service stability, then its not powertrain related. not a cat, has nothing to do with poor fuel. unless the engine is misfiring, or other concerns exist with drivability. if not, then its not going to disable the stability system.

the reason that it resets after you turn the car off, is because it IS resetting itself. when it comes on, you need to take it to the dealer, do not shut off the car, take it directly to the shop, tell them to test it without shutting it off. the problem is current when the light is on. most likely - it is a wheel speed sensor failing intermittently, or wiring from the electronic brake control module to one of the wheel speed sensors. fixed several of them for various rear hub failures, few front hubs, had open circuits in the wiring to the wheel speed sensors, and even have had failed EBCM's. you wont know until the vehicle is tested. there will be a chassis DTC in the EBCM for the fault.

Click to expand...

Very good. I also have had similar issues, the latest being the security light and it took three starts to make it go away.
Often if a wheel sensor is at fault, it will blink a number of times indicating which one is at fault, during the start up.
There is a SB that admits they left diodes out of the cooling fan circuit which exposes all the electronics to voltage spikes. This is one of several things that are very damaging to electronic components, especially semi-conductors whether it is a simple transistor or a computer chip. Sometimes such a spike will just kill the component, other times it damages it with a shortened life expectancy. The surge punches a hole through the PN junction and can cause a short at that point. If it is a relatively tiny hole it may only cause leakage, but also a hot spot that might eventually kill the component. Also shorts may be temporary such as when you turn off power and it does not show as a problem when power is reapplied, not immediately anyway.
There have been some posting that seem to connect dead ECM, TCM, and ABS to it.
What burns me up is they did the same stupid thing during the '90's with the Aurora and they are doing the same fix for this one.

engineer25 said:

Is there one single thing you like about this car????

Click to expand...

It really makes me question the engineering I must admit.
The combination of the I4 to the A6 was a big plus. Better pep and mileage, and I said "was" because of something that came to light yesterday, but not sure if it is just mine or a flaw in A6.

I ran across a post about a shudder at lower speeds yesterday. I too have it sometimes but was having real trouble trying to decipher where or what it was from.
It seems I may have gotten a big clue yesterday when starting from temp of 49. A bit cooler than we've had most days. When it shifted to third gear, it felt very much like it had slipped into neutral. Light but steady accel and several stop signs before leaving my neighborhood with speeds up to 35 mph.
I start watching tach. Instead of settling to the shifted RPM, it sluggishly dropped about half of the RPM, hesitated, then dropped the rest of the way before having positive engagement.
The amount of time that clutch would have been slipping is very disconcerting. I have not seen a break down of the tranny, but following what normally happens with electronic shift vs mechanical valve body, it seems highly likely that some sort of internal leak is occuring at cooler temps. Since it did not occur at other shifts, that seems most likely.
The complaints of shudder match the range of speed. The difference might be temp. Assuming no leaks, then it might be tied to pressure regulation, except then it would seem to be the same across all gear changes, except if the 2-3 shift engages another clutch without disengaging a different one. Then, there might not be enough volume & pressure to positively lock as it should.
Anyway, still a mystery, but needs deciphering.

clane3789 said:

What is causing this??

Click to expand...

Welcome to the world of electronics.
Any component in the system may have a problem. Wheel sensors, computer, wiring, electronic brake control module.
There is a TSB that apparently does not address all vehicles since the 09 I had was not in the covered, but it did not have the diodes or the fix for the missing diodes. The diodes were to be installed across the fan motors. When the fan control relays are actuated it causes a inductive spike apparently and the diodes are to kill it.
This is a long issue with GM apparently since it was also noted on 96 Aurora which I acquired used and it had the fix harness installed. The missing diodes were blamed for killing electronic brake control module. HELLO! So I was shocked to see the same missing diodes issue on 09 Malibu and the same exact fix. Let me say if spikes are killing it, they can also kill any electronic component. In that way they are a bit like lightning, looking for the easiest path. Often they do not outright kill a semiconductor, they punch a small hole through a PN junction which creates current leakage in the device junction. If the hole is big enough it is flat dead. If it is small the current leakage creates heat until it shorts out. Removing power or cooling often allows it to work normally for a period of time such as getting hot again. Apparently the EBCM is the weakest spot in a significant number of vehicles so that they were able to find the issue. But it can be any other electronic component in the vehicle that gets the damage from the spike. Remember it is looking for a path and like lightning will take the easiest, so by normal deviations during manufacturing process other components may be the easiest path.
And BTW, sometimes no issue surfaces for a long time. But it has been shown that the life of effected semiconductors is shortened tremendously.
You will also find such stuff is generally only covered under base warranty.
The next time the lights come on, drive directly to a GM dealer, do not shut off until they agree to document it.

09 LT2 I4A6 Yes, shut down reboot. The fancy stability control failed me. I actually saved the vehicle on side skid because of ice snow experience. Firestone were not Touring as stated on window sticker. Tires alone would not fix problems. Easily wander on slight bump. Learned of recall effecting ABCM, but did not include my VIN. Same exact issue existed on 96 Olds Aurora, with exact same fix. Malibu had neither missing diodes or fix. Acted like sticking caliper, decreased braking. Stopped in middle of intersection, finally. Dangerous vehicle and EPS would try to steer off road ~once/1000 miles. Lemoned it for 11Lacrosse $43K. It was even worse. Lemoned it too. GM, per Leslie Stahl program, claims they have new testing at GM. GM man stating, "When we tested the Lacrosse, it was a big disappointment", raises confidence little. Dealer could not fix several issues on either vehicle. GM replacement parts may have been rejects. Dealer has to follow GM instructions to get paid, even when it is wrong.
Not all GM have been bad. They may have been doing what it appears Honda is doing on badly reported 2013 model. Taking profit, to make up for loss, by cutting corners, cheap parts, just letting garbage slide.
Good Luck