Brake and Turn Signal Problems with Mercedes

[dougderocker]

We are towing our 23 foot Safarai with a 2007 Mercedes ML320CDI. The brake lights pulse when the brake pedal is depressed. Additionally, although the turn signals on the trailer operate normally, the dashboard turn indicators blink rapidly as if to indicate a bulb is out. Also we are receiving trailer turn signal and trailer brake light error messages on the dashboard. Has anyone else had this problem and know the fix?

[DanB]

Hello!

I see that your Safari is new, but I would suspect a grounding problem. Are you using a brake controller?

Has this problem just started, or have you always had it?

Just last night I had a funny incident. I installed new brakes on my 1970 safari. This is probably the first time those wheels have seen brakes in twenty years.

After installation, we hooked up the durango to test them. While I'm pumping the pedal, my 15 year old kid is sitting next to the axle laughing on the ground.

After questioning him, he shows me the light above the gaucho going on and off everytime the brakes are depressed! Hmmmm. Might be a problem! But, Makes for a great third brake light!

[ScottW]

One other possibility to consider. Many vehicles require a heavy duty flasher when attached to a trailer....just my 2cents worth.

[2airishuman]

hi dougderocker and welcome to the forums....

the diesel merc is nice...

we've had several members post regarding 'pulsing' issues with newer a/s.

and euro haulers like rover, vw and now merc

it may be related to the leds on the trailer or the electrical harness/fault codes.

don't these led lights pulse at some rapid frequency (that the human eye doesn't detect)?

anyway herez 2 small threads to get ya started looking.

LED Tail Light Problem

http://www.airforums.com/forums/f447...ver-30609.html

euro tow vehicles are uncommon enough here that the references are thin.

but look in the touareg threads.

also this issue has been discussed on the vw/t-rex forums.

let us know what you find.

cheers
2air

[Tom Nugler]

2air has hit the nail on the head. The Touregs had 3 TSB's regarding reprogramming the trailer lighting module. I would suspect the Merc would likely have the same issues.
Check with the dealer and see if they have any flashes available.
While you're at it, see if they have software updates for any powertrain component. Over here at VW-Audi we seem to get a flash every other week or so, sometimes for cars as much as 7-8 years old.

Good Luck,
Tom.

[puppybear]

i am soon to be hooking up a 1965 overlander to a 2000 mercedes ml430 do you think this might happen here or is it only a problem if the lights on the airstream are LED lights ...... thanks

[Wayne&Sam]

I pull with an ML500. Did you get the towing package from MB? That would include the wiring adapter to make everything work properly.

[lewster]

I don't know what MB uses as a tail light converter on the ML series to combine the 3-way MB tail lights to the 2-way tail lights on the trailer, but I have had success using a heavy duty converter that has a power and ground lead also.

I tow with an '04 Dodge (Mercedes) Sprinter van made in Germany and I had the same problem until I used the new light converter. It might solve your problem too.

[JuliaPowell]

Puppybear -

I don't think the American red indicator lights are legal over here in the UK, to avoid the hassel we purchased a tailboard that we fix temporarliy to the rear bumper. Be aware that the department of transport sets certain regulations regarding lights on trailers over a certain size, aswell as other towing/width/length restrictions. The chances of being stopped are minimal but be aware of it !

[racoco]

Afternoon all -- we just went through the pulsing LED tail lamps on our 2007 Bambi hooked up to a Land Rover as TV. The problem wasn't grounding or anything at all with the trailer or the connection; it was the Land Rover. Apparently not all cars are "compatible" with LED's; or at least that's how Land Rover chose to explain it.

Our Land Rover sends a micro-volt pulse to the lights constantly to detect burnt out bulbs. LED's use such little voltage, they pulse. 12V lamps don't. To stop the pulsing, load resistors have to be added to the circuit to create enough resistance that the Land Rover thinks everything is ok.

Dealer also told us this happened on a VW recently and VW actually supplied a fix at the trailer connection point. No such luck from Land Rover; we're making a new umbilical with the resistors mid point in the cable. The new cable is short and will plug in like using an extension cord. It will stay with the Land Rover since that's where our problem lies.

Good luck.

[dougderocker]

After several months of pulling our hair out (along with Mercedes and Airstream) it turns out that the problem is the micro-volt pulse issue as described above. With a little arm twisting Airstream volunteered to change the LED lights out to OEM incandesent lights which did the trick. This should work for all types of tow vehicles that send out the micro-volt pulse. Airstreams Electrical Engineer also indicated that they were also working on a circuit board fix for the problem.

[Alumin8]

This is very interesting and not something I ever considered. I have been wanting to change my tailights to LEDs for inceased brightness and lower it power used. I think I have changed my mind. There are enough things to manage in an Airstream without worrying about pulsations.

[Devoman]

One of the problems can be solved with resistors.I did this with my previous Airstream but I have not done it with the one I have now.Once the warning shows up I can make it go away instantly or it will go away on its own in a few seconds.You should be able to find it somewhere in my earlier posts.If not here it will be in the Touareg forum on clubtouareg.com.Andy R also owns this site as well.