[obermd]

What I want to know is why do the Traction Control and Stabilitrak systems turn off for any Check Engine Light? I can understand if there is a problem that impacts the ability of the car to sense and respond to skids, slides, and body rolls.

Leave your gas cap off and when the P0477 (evap system leak) light comes on you lose the TC & S systems. O2 sensor goes out in the exhaust - ditto. Vacuum leak - ditto. I suspect this is a regulatory issue since Toyotas do this as well, but I'd love to know where this requirement comes from.

 

[brian v]

MAN !
I really think that it could be that faital flaw that we are seeking .
This could become an interesting Topic to disect .. now here is a hint , Program .

 

[jblackburn]

Electronic throttle bodies.

"Limp mode" disables all of these systems and runs the car off a table of default values. Since they all sorta work together, VSC and TC light up as well to show they are disabled.

My guess would be that the car may be unsure of how much power it's actually putting down (like if a MAF or O2 sensor were bad), so it doesn't know how things would be affected if it were to cut engine power like it normally does if you spin the wheels or start to slide.

 

[NickD]

Least it explains why CHIEFZUSAF TSC lamps came on with vacuum leak problems.

This is something that still amazes when bread boarding a new circuit design, the circuit itself knows if you followed all natural laws in the design. If not, will burn up in your face.

Not true with software, can lie like crazy and still get away with murder. And nothing will burn up in your face.

 

[spacedout]

I think these are disabled due to bad/erroneous data from any related system sensor. With that said any DIC error message you get might not have anything to do with the actual problem. When my engine went 3 weeks after buying my cruze, my DIC was indicating service traction control/stabilitrac. Not sure how a broken valve, piston with hole in in and shrapnel damaged turbo/intercooler caused this error.

 

[NickD]

With a vehicle like my old OBD I 92 DeVille or 88 Supra, any error code can be displayed on the IP, came from the factory this way. Just needed a list to explain what those codes meant. When switched to OBD II, was laying out 5,600 bucks for a GMtech II scanner that did essentially the same thing.

The check engine lamp is one big fat "OR" gate that outputs a logical "1" for any of a several hundred different codes. Don't know if your EGR valve is burning up your engine or your gas cap is loose.

My point is, that can also use that logical "1" to disable the TCS, and apparently this is what they elected to do. But don't ask me why!

One reason why I call the CEL a HAL from that odyssey movie, But stands for a Heart Attack Lamp!

 

[obermd]

I can understand these lights if there is an engine power issue such as limp mode, but leaving the gas cap off - really???

 

[blk88verde]

My engine and turbo recently grenaded themselves and lost about 2 qts off oil, no check engine light, nor tc or vsc lamps.