My 2006 is giving me a warning that I have a failed lamp.

However, a visual check shows that all lamps work.

Anyone have an idea why it is throwing a fault message?

 

Center brake light? Most people miss that one. If not that - one of your bulbs may have a microfracture that periodically opens for a second, or the connections to the sockets or the bulb in the sockets may have corrosion and/or be intermittent.

 

Thanks. All three work.

I need to tear them open and inspect for oxidation on the contacts.

 

Also, low battery voltage can cause false warnings about brake lights or other lights. If your battery is old, that could be an issue and some 955s have 2 batteries that have to be replaced... one under the driver's seat and one under the spare tire. If you replaced the one under the driver's seat, but not the one under the spare tire, the old battery can be discharging the "good" battery under the driver's seat.

If you have pitting where the contact in the light socket where the tip of the bulb touches the spring-y center contact, it can be tricky to get that socket working reliably again, only because the surface is no longer smooth. Once the pitting starts, it keeps on going over time. The sensor circuit for lights bein out relies on resistance... the sytem senses higher than normal resistance and displays the warning message. So the filament doesn't have to be completely broken for the resistance to go "higher than normal". If you've never seen a brake light not working, chances are the contact points in 1 or more sockets are the source of the error... Assuming your battery or batteries are in good condition.

 

Excellent information.

I don't know about the battery condition other than when I start the vehicle it cranks fast and without delay.

When I get a chance I will inspect for oxidation on the contacts and the bulbs.

Thanks!

 

On these Cayennes (957 and presumably 955, not sure about 958), the power lift gate is the first thing that you will notice is either working very slow or not at all. Engine cranking speed is not diminished significantly at that point. Biut if you are having random light failure messages (I've had brake lights, headlights, and side light errors when nothing was wrong except a weak battery) and the lift gate seems slow or won't open at all, battery voltage is likely your issue. It is not uncommon for an owner of a 955 to replace the battery under the driver's seat and not know about the battery under the spare tire so that old battery sits there doing no good until iit gets bad enough to drain charge from the "good" battery. The low battery voltage issue generally begins with warning messages about 1 or more light circuits. At that point, everything, including the lift gate is working fine. As the battery gets weaker, the frequency of the false light warnings will increase and you eventually get to the point that you notice the lift gate is getting sluggish or stops working completely. So you may not necessarily experience the lift gate issue with 1 new battery and 1 old battery... the new battery may be good enough to keep you from experiencing lift gate issues if it is getting charged well by the alternator.