Stabiltrack and traction code from bad coil

[jhall]

Hi all,

Experienced an interesting problem with my 2009 DTS.

Had a misfire start when sitting at a light. Completely lost a cylinder. Fortunately, I was close to home.

As I pulled away from the light, the 'Service Engine' light came on with the 'Service Traction' and 'Service Stabilitrack' messages.

Got home and pulled injector connectors for each cylinder and narrowed it to the bad coil. Picked up a new one today.

The question is why the system coding also shows a misfire as a traction issue.

I've read that other problems can also cause the traction codes to throw, even though they are not directly related - steering wheel off center, etc.

[Cadillac Jim]

Actually a dead cylinder, off-center wheel, and other issues that have any affect on control will indeed affect ESC, TCS, and ABS. You might call OnStar and get all your codes. That may tell a different story.

[guyslp]

Not that this is directly Cadillac related, but just so you know that you're "not alone" in this sort of behavior.

I have a 1999 Jaguar XJ8L that has on more than one occasion thrown spurious OBD codes in addition to the one related to the actual problem. Generally, the "root issue" has been easy to pick out based upon the actual observed problem the car was having.

Cars today (and, since 1999 was definitely yesterday, for a while now) have wildly multiplexed computer systems and, though they're supposed to be fault-tolerant, can have some weird interactions with each other that are very hard if not impossible to explain.

In the Jaguar, even a weak battery that's more than strong enough to crank and start the car can trigger things like traction control and/or ABS failure warnings, among other things. There are also times when the automotive equivalent of a "hard reset" on a computer (holding in the power button until the thing just shuts off) is the only way to get things back to a normal baseline. Disconnecting the battery and waiting several hours, or disconnecting both cables from the battery and touching the disconnected positive terminal to the disconnected negative terminal, performs the "hard reset" function on a Jag. I'd imagine this would be the same on virtually any computerized car, since that action discharges the various capacitors in the systems that allow volatile memory information to be maintained.

Brian, who's dealt with more P030X codes than I'd like to remember [Denso ignition coils are not my favorite]

[Cadillac Jim]

I suggest that you browse Rock Auto, Summit Racing or other reputable vendor for aftermarket coils if you find OEM coils unsatisfactory. Mallory, Accel, and others offer great premium coils suitable for street and daily driver cars. Upgrading to CDI multi-spark is hard to resist once you know it's out there, too.

Everything you say applies to most OBD cars. In the 1997 FSM for Cadillac E/K (Seville/Eldorado/Deville), I have found that several modules will throw a code if the battery voltage drops below 10 Volts during starting, and some modules will malfunction if the voltage goes below 9 Volts. I have heard of radio and other complex modules that can have difficulties that are resolved by removing the battery ground cable for a minute or two. Since this can happen with a perfectly good car with a low battery, it's not trivial.

There's another phenomenon that I have seen on my car and have heard of many times: power-washing under the hood or under the car can cause temporary shorts at connectors in the wiring that result in many OBD codes, some of which can even cause driveability problems or other quirks, that go away when the car is left to sit for a few minutes or overnight, and scads of strange, unrepeatable HISTORY codes remain until they are cleared. I call these "car-wash codes."

But, the alternative is the clunky and inaccurate mechanical distributor, carburetors or mechanical fuel injection, vacuum-servo operated transmissions, and no OBD codes to help you maintain your car. I'll take a module-oriented auto over the "good old days" in a heartbeat for a daily driver for the long haul.

[jhall]

Thanks for the replies.

I dropped in a new coil from the dealer and made a few trips. All traction codes cleared immediately and the "check engine" light dropped out after about 5 trips around town.

Being familiar with software and control systems, the entire 'bogus' codes just appear to be less than quality software development that was pushed into production. Granted, they don't build these with consumer repair in mind, but having multiple potential faults that could trigger what's pretty much an unrelated code seems pretty messy.

One saving grace was that the coils are independent and are cheaper ($115) than a $250+ coil pack from the earlier N* designs.

Guess I'll keep her a little longer

[winterset]

I believe those safety features when activated, cut power to some cylinders. Probably the software detected one of the target cylinders was offline, so it correctly threw a code to let you know this.

[jhall]

Well,

I would not expect the stabilitrak and traction control service messages to show up for a misfire - much less the conditions that Cadillac Jim mentioned which can also cause these same message to appear - the cause and effect is just not properly associated to the actual fault.

The service engine light did appear. I would assume that if I plugged up a code reader, it would show the P3XX code for the particular cylinder. There was no additonal power reduction - just the one cylinder dropped out.

If the actual software logic in the engine controller had the proper number of checks, it would 'see' the misfire, or steering wheel position, etc) as the primary fault and not allow the traction codes to be set. As I mentioned, the software coding robustness is not geared to the benefit of the owner and the dealer is paid (very well) to trouble shoot back to the actual source of the problem.

[Cadillac Jim]

I once had a P030x code with MIL on, on a 1997 ETC, and it had no other codes. The MIL light would not come on until the miss count exceeded a given threshold in the software, which took a while because it missed only at idle and not all the time.

I expect that a hard miss, i.e. a dead hole, would affect systems that used the throttle in a throttle-by-wire car like the 2006 and later. Since TC and Stabilitrak use the throttle, I can see intentionally turning on those lights. I cannot see setting codes that indicate that other components need service.

[guyslp]

To follow-on to Cadillac Jim's post, the way the OBD-II system works definitely varies by type, "severity," and frequency of a given event.

I can guarantee you that if you were having a continuous misfire on a cylinder or cylinders there is no way that you could miss it.

As Jim mentions, for virtually any non-critical and highly intermittent occurrence, a code will either not be set or it might be set but with no MIL/Check Engine illumination. If something is either continuous/ongoing or has occurred enough times within a certain time span then the MIL/Check Engine will be illuminated.

What most people don't know is that the MIL/Check Engine can and will be turned off if a given issue stops occurring and does not recur for a set number of car start/shut off cycles. I've had several of these on my 1999 Jag and I wish I could remember what the actual codes were. I do know that the number of start/shut off cycles varied based upon the "severity" of the issue indicated by the code itself. Some issues, like stability control failure and gearbox [transmission] failure, do not even cause the MIL/Check Engine light to be illuminated, but codes are set related to both. In the case of the specific examples I just offered, both stopped happening after the battery was replaced in the car. What amazed me is that on this Jag there appears to be no monitoring of whether or not the battery is being charged correctly. The Cadillac from ten years prior has a "no charge" warning and a dedicated "idiot light" (which I don't think are for idiots - thank you) dedicated to that warning.

Brian