Light burnt out indicator, but no lights out

The MFD says the license plate lights are out, but they're not. I asked the stealership to tell me what I was missing, instead they charged me for replacing the lights and then told me they had no idea what was wrong. Anyone here have this issue? Indicator light on the dash has been on for 4 years now and I'm still annoyed by it.

Find someone nearby with VCDS and have them run a scan. I looked for a long time before getting VCDS. I did find a burnt out light in the glovebox, which I would not have expected to trigger the 'light out' light...

The console display specifically says it's the license plate light. How would VCDS help?

Oops. Sorry. Have you tried disconnecting the battery? This fixes many of the intermittent warning lights on VWs.



1
Clean any corrosion off of the battery and terminals with a can of spray-on battery cleaner. Disconnect the negative battery cable and then the positive cable with a combination wrench. Clean the battery posts and terminals with the post and terminal cleaning tool, so you have a good connection when you’re done. The best type of tool is the wire-brush type. With the reamer type there is a danger of taking off too much material and causing a loose connection.
2 Hold the positive and negative cable ends together so they're touching each other but not the battery.


3 Wait five minutes for the diagnostic information to be erased. Install the positive battery cable and then the negative cable. Program any radio or security codes following the manufacturer’s directions.

1) Disconnecting the battery does not clear codes
2) The issue is not intermittent, it has been the same for 4 years. The battery has been disconnected multiple times and replaced in the last 4 years that the light out indicator has been coming on.
3) The light out warning light resets every time I start the car and turn the headlights on. When the car starts, it is out, license plate lights only come on when I turn the headlights on, and within a second, the warning light turns on and text display pops up. The dealership couldn't figure it out, I can't figure it out, the lights work just fine, and I'm still annoyed by it.

Have you tried a higher wattage bulbs? I would check the connections for loose or striped wires.

dandywriter's post has some merit to it. Sometimes on CanBus cars electrical things will misbehave because a capacitive charge can build up in a system and touching the battery cables together will discharge it. Also check/clean/tighten chassis grounds in the vicinity of the trunk and in the engine compartment.

I had a window regulator that quite working and when I went to install a new one I reconnected the plugs to the old one and it started working again. Not exactly the same as touching the cables together but the old motor was unplugged for several weeks. CanBus stuff can work kinda spooky sometimes is my point.

Make sure the sockets are not damaged or have corroded connections and the bulbs are the correct type/wattage. A corroded socket is enough to set the bulb out light even if the bulb is not actually burned out.

Am I correct in thinking both license lights are working, but the dash says "license plate lighting out" or words to that effect?

Just for fun I disconnected one of my lights and started the car, there was no indication of a problem until 10 seconds after I turned the lights on when the message came up. Shutting the car down and restarting I didn't get an error message again (2nd time) until 10 seconds after I turned the lights on. I believe this is different behavior than with a burnt out headlight or brake light. In that case the car checks the circuit continuously, but in this case it is only checking when the light is turned on.

I think all the car can check for is the current draw (amps) and in your case it thinks the amperage is too low when the lights are on. Assuming this is so, there are two reasons I can think of which could cause this: first the amperage is too low, and second the device in the BCM (body control module) which detects the current isn't working right. Short of replacing the BCM the only issue you can deal with is the first one.

My understanding is that in this case the BCM can be simplistically though of as a master set of relays which switch to allow current to flow to the various lights. There is a large 12 V feed wire to the BCM and multiple smaller wires which run to various power users and then to ground.

I think low current draw could be caused by corrosion on any one of many connectors between the current source (BCM) and the final ground connection. Are both the lights the same brightness? If not the dimmer one is likely causing the problem. Caper's solution above might be the simplest one - a higher wattage bulb might pull enough more amps to trick the BCM into thinking all is well.

If you want to find the cause of low amps I think you could check current flow by measuring the voltage drop between the positive battery terminal and the hot side of the bulbs and between the ground side of the bulbs and the negative battery terminal. I would try this by backpinning the connectors with the lights turned on and bulbs illuminated. You should be able to confirm that there is minimal drop between the positive terminal of the battery and the hot side of the bulb and between the ground side of the bulb and the negative terminal of the battery. If one of these is bigger than one volt then that is the circuit where I would start looking for corroded connectors, damaged wiring, or something else causing a voltage drop.

Having written that I think what a lot of work and can anyone reliably measure small voltage drops accurately enough without special tools? Maybe not. Probably just easier to look for corroded connectors in likely places - battery terminals, around the lights themselves, around the fusebox, the ground connector, the connector between the hatch and the rest of the car.

Am I correct in thinking both license lights are working, but the dash says "license plate lighting out" or words to that effect?

Just for fun I disconnected one of my lights and started the car, there was no indication of a problem until 10 seconds after I turned the lights on when the message came up. Shutting the car down and restarting I didn't get an error message again (2nd time) until 10 seconds after I turned the lights on. I believe this is different behavior than with a burnt out headlight or brake light. In that case the car checks the circuit continuously, but in this case it is only checking when the light is turned on.

I think all the car can check for is the current draw (amps) and in your case it thinks the amperage is too low when the lights are on. Assuming this is so, there are two reasons I can think of which could cause this: first the amperage is too low, and second the device in the BCM (body control module) which detects the current isn't working right. Short of replacing the BCM the only issue you can deal with is the first one.

My understanding is that in this case the BCM can be simplistically though of as a master set of relays which switch to allow current to flow to the various lights. There is a large 12 V feed wire to the BCM and multiple smaller wires which run to various power users and then to ground.

I think low current draw could be caused by corrosion on any one of many connectors between the current source (BCM) and the final ground connection. Are both the lights the same brightness? If not the dimmer one is likely causing the problem. Caper's solution above might be the simplest one - a higher wattage bulb might pull enough more amps to trick the BCM into thinking all is well.

If you want to find the cause of low amps I think you could check current flow by measuring the voltage drop between the positive battery terminal and the hot side of the bulbs and between the ground side of the bulbs and the negative battery terminal. I would try this by backpinning the connectors with the lights turned on and bulbs illuminated. You should be able to confirm that there is minimal drop between the positive terminal of the battery and the hot side of the bulb and between the ground side of the bulb and the negative terminal of the battery. If one of these is bigger than one volt then that is the circuit where I would start looking for corroded connectors, damaged wiring, or something else causing a voltage drop.

Having written that I think what a lot of work and can anyone reliably measure small voltage drops accurately enough without special tools? Maybe not. Probably just easier to look for corroded connectors in likely places - battery terminals, around the lights themselves, around the fusebox, the ground connector, the connector between the hatch and the rest of the car.