Check Brake Lights warning

Jughead028 · #1 11-07-2018, 06:10 PM

On the weekend I towed a trailer with faulty lights, and now I am getting a warning message "Check Brake Lights" and "Check Tail Lights" every time I start the car.

How can I reset these warnings?

JG

wpoll · #2 11-07-2018, 08:43 PM

If you don't have any dead lamps on the car (and the trailer is no longer connected) then it's possible the faulty trailer damaged the LCM (LKM).

Do you have the trailer module fitted or is your trailer wiring just connected to the existing tail light wiring?

One of the task of the trailer module is to isolate the trailer wiring from the car, along with monitoring the trailer lamps, setting towing mode in the ABS and DSC modules and disabling the rear PDC system.

If everything is working, the trailer is not connected and you still get these warnings, I suppose you could code out the hot and cold monitoring for the tails - that might kill off the warnings. But something is amiss here...

Jughead028 · #3 11-07-2018, 09:12 PM

To be honest, I don't really know how the trailer connection was made as the tow bar was already on the car when I bought it.

All lights on the car are working correctly.

Given everything else on the car, I suspect it may have been connected directly, especially if it is an aftermarket tow bar and not genuine BMW!

I don't even know if the lights of the trailer are faulty or if the car wiring is faulty!

A curious thing though - I don't get any error message about the indicators, but they were also not working on the trailer.

Any way of telling without dismantling the whole rear end?

Any easy re-set method I can try first?

wpoll · #4 11-07-2018, 10:55 PM

Quote:

Originally Posted by Jughead028

To be honest, I don't really know how the trailer connection was made as the tow bar was already on the car when I bought it.

All lights on the car are working correctly.

Given everything else on the car, I suspect it may have been connected directly, especially if it is an aftermarket tow bar and not genuine BMW!

I don't even know if the lights of the trailer are faulty or if the car wiring is faulty!

A curious thing though - I don't get any error message about the indicators, but they were also not working on the trailer.

Any way of telling without dismantling the whole rear end?

Any easy re-set method I can try first?

There's no reset for the lamp check warnings, save actually fixing the fault or possibly coding out the test/warning.

The signal lamps are not included the E53 lamp monitoring, hence no warning about them failing. Failed signal lamps are indicated by an increase in the flash rate when the signals are activated.

It's pretty easy to tell if the trailer module is fitted.

1. There's a small white plastic module in the trailer module install location in the tyre well (next to the battery),

https://blog.bavauto.com/12384/bmw-x...e-install-diy/

or...

2. The rear PDC system turns off when you connect a trailer, or..

3. You get warnings about failed trailer lamps.

Sounds like you don't have the trailer module fitted and the trailer wiring is directly connected to the car's tails lamp wiring. This can cause a number of problems - and maybe yours.

You could try a battery pull - disconnect the battery negative terminal for a few minutes then re-connect it to see if that resets the warnings but I don't expect it to do so...

bklyndiaz · #5 11-09-2018, 08:08 AM

Hi guys, I have the same warning on my dash check brake lights, and check tail lights
This warning started about a month ago, no trailer tow like OP.
There is a way to test lights with INSTA D. My test showed "faulty" left brake light, but LIGHT is still good when I use Signal, brakes etc.. no visible fault,
Can or is INSTA D predicting a failure before it happens? Not sure, just sharing my story.. thanks 2006 x5 3.0i

80stech · #6 11-09-2018, 11:50 AM

You guys might just be dealing with the erroded contacts in the bulb holders problem.

mario4705 · #7 11-09-2018, 03:40 PM

Quote:

Originally Posted by 80stech

You guys might just be dealing with the erroded contacts in the bulb holders problem.

Either that or the entire assembly has to be replaced, i did this once for both assemblies

Jughead028 · #8 11-09-2018, 09:11 PM

Well, Good News, Bad News!

Faulty globe was causing the problem.
Good News - changed the globe and all is right now.

Bad News - Son is an idiot (he checked if lights were working)!

Also, trailer is wired straight to the light wiring, not through a trailer module.

Ah well, I will just have to live with that I guess!

Thanks for all the help.