Rear lights flash when all lights are switched off

[Cutac]

Hello

Me again with a small issue with my C4

Don't know when it started, first sighting of it was Thursday evening.
I was entering my yard so I switched off dipped beam and switched fog lamps on(started doing this recently ). I stopped got out of a car to hear something(belt squeak I've been battling for a year) and decided to kill the lights. Did that(rotated dial to "0") and I saw rear lights + plate lights flash. So when dial clicked on "0" everything on rear shut of and turned on in a second.
Tried all other combinations of turning off the lights but it only happens when fog lamps are on(front or front+back, no difference) and lights are turned off using the main dial(switching to "0").
Doesn't matter if dial is on side lamps or dipped, same thing happens. Tried switching LED plates to halogen, same problem.


Now, I've had my rear lights set to run simultaneously with DRL's by a dealer, but I've never ever paid attention to what's happening on the rear when lights are switched off, so I can't tell if that's the problem(I'll take her to the dealer to rule that one out(or solve the problem ), but in two weeks).


Any ideas what could be causing the problem?


Thanks

[Hell Razor5543]

If the LEDs you have fitted are not CANBUS compatible they can cause some issues, according to what I have read on the forum.

[Cutac]

The ones I've been running for a year aren't, but the problem's there with Canbus LEDs and halogen W5W, too.

[GiveMeABreak]

As James says this sort of thing can happen with LEDs if they are not the right type - typically flashing when switched on or remaining on after the lights / vehicle is switched off for a while. Have you replaced any other lights on the car (front or rear) with LEDS apart from the rear number plate lights? If not I suggest you try a BSI reset:

• Put the driver's window down, lift the bonnet and ensure all equipment is switched off.
• Ensure all doors are closed and remove key from the ignition.
• Wait for 3 minutes, disconnect the vehicle battery and wait at least a minute.
• Reconnect the vehicle battery, wait a further minute (do not open doors).
• Switch on the side lights through the driver's window.
• Switch on the ignition and check system's functionality.
• Hold lock button on key down for 10 seconds.
• Remove key open & close door test central locking system.
• Start the engine and complete the system's check.
• Failure to follow this procedure could result in incorrect operation of many BSI related items.

[Cutac]

No other LEDs, just plate lights.

BSI reset won't reset any settings made changed via diagbox(or whatever's it called)?
Also, might be a stupid question, but, do I open the door between these steps?

Switch on the side lights through the driver's window.
(opens door?)
Switch on the ignition and check system's functionality.

[GiveMeABreak]

No the BSI reset will not change any settings changed by a Lexia / Diagbox. It can cure some electrical gremlins though. Open the bonnet first so you can access the battery and have the drivers window wound down so you can reach in later. Never open the doors or switch anything on electrical whilst performing this procedure. When you are ready and have shut all the doors, wait for the 3-4 minutes before disconnecting the battery negative.

Then wait for a good few minutes before reconnecting and try to get the lead back on in one go without connecting disconnecting again. Then follow procedure where necessary.

[Cutac]

Alright, thanks

I'll try that next weekend if it stops raining.

[GiveMeABreak]

Just a cheap way of eliminating the obvious and if you still have issues then investigate further, checking the wiring connectors and earths.