What exactly did they "tune up" on the Avalon? Possible they disconnected a sensor wire while tuning up and forgot to hook it back up. Also possible they damaged the ECM if they tried to read it with an incorrect protocol. Hard to say for sure, need a bit more detail.
Hi: Thanks for your reply. I really cant tell you what they might have done when the tune-up was done other than, replace plugs, replace timing belt,water pump, theroostat, and did a injector cleaning via the injector service ? They have tried to reset the idiot lites via ther're hand held computer. no flauts were found, disconnected the battery over-nite with no results. Thats the best I can offer. Thanks for any help
PS> I would check for disconneccted wires as suggested by fishexpo. There are any number of things they could have scred up. Check each wire-to-fuel-injector connection. See if they are still in the same order! Check all wires are on tight. Finally take it to someone who has the "good" scan tool...
Sounds like they did a lot to the car - but none of what they have done should have caused a problem with the VSC system.
I can see the timing belt with water pump and thermostat - good thing to have done every 60K-100K for the timing belt (water pump is right behind it - saves you quite a bit of labor to have it done at the same time). Plugs are normal routine change (every 60K for platinum tipped plugs). Injector service - the car probably didnt need it - sometimes they make the car run a bit odd afterwards.
Some systems are a bit more sensitive than others - I remember a case where a cell phone plugged into with a 12V charger caused the yaw sensor to report a problem, kicking on the VSC lamp. The light should have reset with a scan tool - if it comes back on immediately afterwards - then I would suspect the shop probably screwed something up.
Now that you mention it, I cant figure out how any of the things I suggested checking could set the VSC light.
Wonder if dirt got into a sensor or something while they were working? I had that happen to the ABS on my now-departed (to someone else) Neon. What sensors does VSC check? Traction control and ABS are integrated into that right? Or do they have separate lights for ABS?
The VSC sensor is an accelerometer/yaw sensor - it is tied to the ABS system as well as the engine. When the sensor detects a shift in the vehicle body vs what the wheel sensors are saying, then it assumes the car is sliding - cuts engine power briefly and applies the brakes on the wheel that will pull the car back on track. Kind of works like traction control - but traction control is more interested in lateral acceleration changes (ie. straight line traction). ABS is the opposite end of the spectrum - also deals with lateral acceleration under braking. VSC and EBC work together to deal with everything else.
Still kind of weird for the light to come on - I know in Scions and Prius - they got the light to come on and stay on via shorting of pins in the dignostic connector. If the VSC is off - then the ABS is disabled as well. Might need to take this in to a Toyota dealership and have them take a peek. If they can find out what is wrong - it will be well worth the $85 diagnostic charge vs tossing darts at it. They would also be able to find out if any damage was done to the ECM (static discharge?) during the previous service. Might go a long way in getting you some compensation if they other shop fried the ECM.