Trailer Lights Warning??
Thread Starter
Junior Member
Joined: Nov 2007
Posts: 26
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2007 ML 320 CDI, 1999 C43 AMG
Trailer Lights Warning??
I have a 2007 ML320 CDI that the dealer installed the trailer hitch on. I've had a problem with the dash indicator for the trailer lights from day one. It started when I had a trailer hooked up and it would tell me that one or more of the lights were out. When I checked the trailer the lights are fine.
I've had it back to service several time and gotten various answers from, LED trailer lights don't draw enough current to the latest TSB for the welding of the hitch was causing the wires to come loose.
Now I am getting these same warning lights when I don't even have a trailer connected...... Of course I think it is the PAM module in the back that is screwed up, but I just wanted to know if anyone else is having the same or similar issues?
I've had it back to service several time and gotten various answers from, LED trailer lights don't draw enough current to the latest TSB for the welding of the hitch was causing the wires to come loose.
Now I am getting these same warning lights when I don't even have a trailer connected...... Of course I think it is the PAM module in the back that is screwed up, but I just wanted to know if anyone else is having the same or similar issues?
Newbie
Joined: Aug 2008
Posts: 1
Likes: 0
2007 ML320cdi
ML trailer lights led - issues
Hi Mike
We have had an ML320cdi for just on 12 months and had hitch and trailer wiring harness installed locally by MB dealer. Were informed by dealer that light emiting diode (led) lights no problem, computer can be programmed to handle them on trailers. Also fitted brake controller. Symptoms were warning messages in dash for rear brake lamp not working, tail lamp not working. After many months of trying options, eventuallly getting the computer black box re-programmed in Germany and air lifted back to Australia, it was no different. In the end the dealer fitted a series of resistors into the lines feeding the trailer to trick the system. It still isn't perfect, as the trailer might not be hooked up at the plug correctly and there is no warning that the indicators aren't working as happened yesterday in traffic, another driver let me know at traffic lights. Initially we were told it was the brake controller. There is I am told an after market system to fool the computer. As there is so little current required to run leds the system will feed into them even with the ignition off, glowing ofr 15 minutes until the systems automatically shuts everything off.
The car has been awesome as a tow vehicle with a 2 tonne Malibu Response LXi to pull, we couldn't be happier, apart from the led issue.
We have had an ML320cdi for just on 12 months and had hitch and trailer wiring harness installed locally by MB dealer. Were informed by dealer that light emiting diode (led) lights no problem, computer can be programmed to handle them on trailers. Also fitted brake controller. Symptoms were warning messages in dash for rear brake lamp not working, tail lamp not working. After many months of trying options, eventuallly getting the computer black box re-programmed in Germany and air lifted back to Australia, it was no different. In the end the dealer fitted a series of resistors into the lines feeding the trailer to trick the system. It still isn't perfect, as the trailer might not be hooked up at the plug correctly and there is no warning that the indicators aren't working as happened yesterday in traffic, another driver let me know at traffic lights. Initially we were told it was the brake controller. There is I am told an after market system to fool the computer. As there is so little current required to run leds the system will feed into them even with the ignition off, glowing ofr 15 minutes until the systems automatically shuts everything off.
The car has been awesome as a tow vehicle with a 2 tonne Malibu Response LXi to pull, we couldn't be happier, apart from the led issue.
Newbie
Joined: May 2017
Posts: 1
Likes: 0
mercedes gl 320
mercedes gl trailer lamp fault
hi, can any one help me please, I have the same fault as the previous chap, ive never had a trailer on my car but when I put either indicator and when ive pressed the brake pedal the trailer lamp fault it illuminated on dash, ive checked the multiplug connector underneath for signs of damp, ive checked the rear lights on car as well as bulbs and nearby earths, can anyone tell me how to sort it I would be most grateful
Super Member
Joined: Jun 2014
Posts: 507
Likes: 25
From: Massachusetts
2014 Smart ForTwo Passion Cabrio
LED trailer lights will not work with a regular trailer wiring adapter, you need one for LED lights. However, MB doesn't carry the damn things anymore, and if you go to a u-haul, for example, they don't even know they carry it! https://www.etrailer.com/Wiring/Tow-Ready/TR20141.html
Out Of Control!!
Joined: Aug 2010
Posts: 12,517
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From: Charlotte NC area
2019 WS222 S450 4-Matic / 2007 W211 E350 4Matic (Sold) / 2008 X164 GL320 CDI
On my GL (Factory tow package) works with LED lights but likes to show trailer light out warnings.
Works fine with regular trailer lights.
Never shows a trailer error when nothing hooked up.
Works fine with regular trailer lights.
Never shows a trailer error when nothing hooked up.
Super Member
Joined: Jun 2014
Posts: 507
Likes: 25
From: Massachusetts
2014 Smart ForTwo Passion Cabrio
Out Of Control!!
Joined: Aug 2010
Posts: 12,517
Likes: 628
From: Charlotte NC area
2019 WS222 S450 4-Matic / 2007 W211 E350 4Matic (Sold) / 2008 X164 GL320 CDI
Not sure why drawing less current (and tripping the bulb failure warning) could cause any issues.
Also, from what I have been told, seems in general the trailer lighting configuration (as standard) follows the brake light type. GLs with regular tail lights expect bulbs in the trailer, and GLs with LED tail lights expect LED trailers.
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From: Massachusetts
2014 Smart ForTwo Passion Cabrio
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Out Of Control!!
Joined: Aug 2010
Posts: 12,517
Likes: 628
From: Charlotte NC area
2019 WS222 S450 4-Matic / 2007 W211 E350 4Matic (Sold) / 2008 X164 GL320 CDI
I still don't believe that running LEDs is going to cause blown fuses, and if it causes other issues, I would be very surprised.
Junior Member
Joined: Feb 2020
Posts: 50
Likes: 1
From: Spring Creek NV U.S.
GL350
Have had zero problems with fuse blowing.
Not sure why drawing less current (and tripping the bulb failure warning) could cause any issues.
Also, from what I have been told, seems in general the trailer lighting configuration (as standard) follows the brake light type. GLs with regular tail lights expect bulbs in the trailer, and GLs with LED tail lights expect LED trailers.
Not sure why drawing less current (and tripping the bulb failure warning) could cause any issues.
Also, from what I have been told, seems in general the trailer lighting configuration (as standard) follows the brake light type. GLs with regular tail lights expect bulbs in the trailer, and GLs with LED tail lights expect LED trailers.
I have LED tail light and w LED trailer it won’t work without LED converted adapter
