jagman78

My car failed inspection and I was told that my "check engine" light was not working. I had the car scanned by the dealer and was told that I needed a right front O2 sensor and mass air flow sensor. Replaced these two items. Removed the instrument cluster and had it checked out. It showed no faults and that the "check engine" indicator was working fine. Don't know what to do next.

JoePGT5S

Do you see the CEL when you first turn on the ignition? (key in and turned to the point just before engaging the starter motor). This is the point where the dash lights are tested and usually what the inspection station would do to determine whether the CEL is not working.

jagman78

CEL does not come on when you turn the ignition key. That is why I removed the instrument cluster and had it checked out.

Prospeeder

The engine light is an LED. If it doesnt come on with key on, the cluster is no good regardless of what place supposedly "checked it out" Its all done in the cluster, even if it saw no ECU signal to the cluster, it would still light up the engine light to say something is wrong. You need a new cluster.

BrianC72gt

Well, The CEL is triggered by the ECU, so I would open the underhood electronics box near the windshield and unplug and plug back in the ECU - not the TCU.

EDIT: So when they "checked it out" did the CEL light actually light up and work for them??

Hey, does the CEL flicker on when you are cranking the engine? Because that would point to a faulty ignition switch.

There are also a couple of fuses to check, you can fish through this thread and find them:

quattroworld.com Forums: 01 S8 died while cruising on highway and it appears that the main ECU is not responding.

Are you sure there are no bent pins on your cluster and wiring in?

I don't believe the CEL has a unique ground, anything else not working?

Oh, and here is a more readable version of your wiring diagram:

http://www.mitchell-auto.ru/UserFile...audi-s8-wd.pdf

Prospeeder

it is all done internal to the cluster. They use Can bus networking to communicate. Sure the engine computer sends a signal to the cluster to turn the light on if there is a fault, but the key on self test of the cluster is independent of that. And if the cluster sees no ECU to Cluster communication the light will come on for a communication Error, or not start at all if its Immo3. his cluster is bad, its not like older cars where each warning light has a power and ground, its all done within the cluster electronics.

jagman78

Any suggestions on where I can have my existing instrument cluster repaired?

silverd2

Who checked out your cluster? ...How?

Did you buy the car used? Did the CEL ever work, since you've had the car?

"IF" your cluster was indeed in need of repair, you can send it to these guys...WAY cheaper and WAY less hassle than a new cluster >>>

VDORepair Instrument Cluster, MID, Navigation Repair Service > Audi A8 & A8 Quattro Instrument Cluster Repairs & Navigation Repairs

If it turns out that nothing is wrong with it, just send the bill to "Skippy the Walmart Tire Boy" (aka "prospeeder") c/o Walmart's apprentice program

silverd2

Kids say the darndest things, don't they...just makes you wanna pick em up and through em in front of a truck.

SOoooo cute, huh? >>>

jagman78

The instrument cluster was sent to BBA Remanufacturing in Taunton, MA. They bench tested it and found no faults. I purchased the car approximately 1 year ago and never remember seeing the CEL on. After replacing the air flow sensor & the 02 sensor the car failed inspection again. It now shows P0491 & P0492 fault codes.