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Discussion Starter · #1 ·
Howdy folks -

I have been having issues with the output of the trailer wiring connector on my 2016 Metris. In general it thinks that some of the trailer lights are out/bad but still turns some of them on. A detailed list of tests/issues is below for those who might find it helpful. I have been installing a Prodigy RF trailer brake controller and everything on the trailer works except the brakes. Controller does not register when brakes are applied, but if I manually apply the trailer brake with the controller it works great and the trailer stops. Trying to determine if I have faulty equipment or there is a "programming" step I need to have applied.


The van was not originally equipped with the trailer package. I added a Curt hitch and the following MB parts per post 56833 in the Fitting OE trailer hitch and harness thread:

A 020 545 40 26 -- Socket -- $54
A 447 540 62 36 -- Electrical Wiring Harness -- $57
A 447 900 41 05 -- Trailer Recognition Control Unit -- $306 (this is the successor/newest part number)
N 0000 0000 32 76 -- Nut (6 of them needed) -- $2.40/each
N 9101 0501 20 01 -- Hexagon Screw (6 of them needed) -- $5.50/each

One note - I did substitute the socket (1st part number) for one from the auto parts store that was listed for a dodge pickup during the Daimler Chrysler era. It has both a 4 pin and a 7 pin socket on it that works better for some of my trailers. I verified the connector and pinout on my 2006 Dodge truck before purchasing and everything is the same. Just for clarity I did also test these symptoms with the factory socket and the results were the same.

Test 1:
As per above, all trailer lights work (turn, running, hazard) except the brake lights. They do not come on at the trailer. Plugging the trailer into other vehicles they work just fine through the same Prodigy RF controller. The metris says that the left, right, and brake trailer lights are out via a dash icon in the middle of the gauge cluster that cycles through for each. The trailer is getting +12V from the power pin of the connector as both the trailer controller and onboard battery charger turn on - they need that 12V to function.

Test 2:
I used a Curt trailer hitch wiring tester (plugs into the trailer receptacle of the van) to see if there was output from the van.

You can search for Curt tester on eTrailer.com as I can't yet post links.

With the van on the +12V test light lights up
Both left and right turn signal lights blink with the van turn signal (dash says lights bad though)
When the running lights are turned on, the test light for running lights turns on
When brakes are applied the tester light does not come on, van brake lights do come on, and the dash says the bulbs are bad.

NOTE: When running the emergency flashers, about every 2-3 seconds the tester's brake light very dimly and briefly lights up. Assuming this is some kind of continuity test the van's electrical system is doing to determine if there is a trailer attached by checking for load. It was not enough to actuate the brakes or brake lights of the trailer when it was attached.


Test 3:

I was not sure if the fact that the trailer uses all LED lights and the tester has only tiny little LEDs was causing the van electronics to be "confused" by not sensing enough current draw and assuming that no trailer was attached.

I took a 6' 7 pin extension cable that I use on my other truck (verified to be good and functional) and started testing. First I hooked the Curt tester up to it and got the same results just to prove it was the same as hooking up to the van. Next I took a pair of incandescent trailer lights (Resistance about 5 ohms so ~30W ea) and wired them between the ground and left/right stop/turn pins of the trailer connector. I ran the extension next to the van so that I could watch the lights. Both turn signals worked in that they lit up the correct bulbs both on turn signal and emergency flasher. Dash still says turn signal bulbs bad. Nothing happens when brakes are applied. Watched them for a while and saw no noticeable lighting from the test pulse.

Summary is I don't think this is an LED vs incandescent light bulb current issue. Open to suggestions for additional tests or other things to try. If you think you want pictures of anything let me know. Hoping to get this figured out soon as the trailer is ready to go but I'm not going to drive it without brakes or brake lights.

thanks in advance.
 

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If your brakes work when you activate them manually, the controller is getting the RF signal and outputting a modulated signal through its brake connection to the trailer brakes so that's OK. The RF controller does not get its input from the brake connection, however. It is activated when both left and right rear turn signals are on together, as in the Metris when braking or when the hazard lights are on.The Brake connection in the socket on the car is not used, (only if the controller were in the car). I am assuming that your trailer uses the same bulbs for brake and turn signal, not separate red and orange bulbs as in some cars. If the turn signals work in test 3 but the brake doesn't make them both light up, I think you have the wrong wiring going to the socket on the van. Do your brakes go on with your hazard lights? You can normally hear them humming intermittently with the flashing (a design flaw in my opinion but that's the way it is).
 

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Discussion Starter · #3 ·
I think that we are in agreement that the RF controller is not the issue here as it worked fine on other vehicles. You bring up good points about some things I did miss in the original post.

The brakes on the RF module are activated by the flashers. The handheld controller goes from .c. to 0.0 when the emergency flashers are activated then back to .c. when they are off. So yes, the controller is picking up when both rear lights are on to activate the brakes.

The Curt test light separates the functions of braking and turning to show which lights should be on. Agree that the metris is not outputting a trailer brake signal on the pin normally associated with a trailer brake controller.

I still can't get the trailer brake lights to go though. Unless I received a faulty component from the dealer I'm leaning against a hardware issue as I did not create or modify any of the wiring myself.

If your brakes work when you activate them manually, the controller is getting the RF signal and outputting a modulated signal through its brake connection to the trailer brakes so that's OK. The RF controller does not get its input from the brake connection, however. It is activated when both left and right rear turn signals are on together, as in the Metris when braking or when the hazard lights are on.The Brake connection in the socket on the car is not used, (only if the controller were in the car). I am assuming that your trailer uses the same bulbs for brake and turn signal, not separate red and orange bulbs as in some cars. If the turn signals work in test 3 but the brake doesn't make them both light up, I think you have the wrong wiring going to the socket on the van. Do your brakes go on with your hazard lights? You can normally hear them humming intermittently with the flashing (a design flaw in my opinion but that's the way it is).
 

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Hi guys I’m having the same problem with my brake lights on my OEM trailer hitch install. Basically I installed every OEM part on the trailer hitch and I still cannot get the brakes to register. I have tried the wireless Kurt system and the prodigy system with another trailer. The turn signals all work and the brake lights don’t work. The trailer hitch guys at U-Haul suggested that I try a seven way flat pin to seven way flat pin LED lamp out bypass adapter.
It’s a little plug-in adapter that gets around the European to North American standard of always having 12 V power. Still no luck. Any help would be appreciated thanks guys

I think that we are in agreement that the RF controller is not the issue here as it worked fine on other vehicles. You bring up good points about some things I did miss in the original post.

The brakes on the RF module are activated by the flashers. The handheld controller goes from .c. to 0.0 when the emergency flashers are activated then back to .c. when they are off. So yes, the controller is picking up when both rear lights are on to activate the brakes.

The Curt test light separates the functions of braking and turning to show which lights should be on. Agree that the metris is not outputting a trailer brake signal on the pin normally associated with a trailer brake controller.

I still can't get the trailer brake lights to go though. Unless I received a faulty component from the dealer I'm leaning against a hardware issue as I did not create or modify any of the wiring myself.
 

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Do you need the dealer to program it?

 

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Thanks- I had the dealer get a software patch/ flash from Mercedes- but still doesn’t work. Really strange. I just want my brake lights to work. So much work for something that with other vehicles is plug and play
 

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Also I was told that Mercedes 7 pins do NOT have constant 12v power... and only supply it when a trailer is connected. So any of those wiring testers you use ( I have one) don’t show much or show a fail because there is no trailer connected. Very frustrating.
 

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Discussion Starter · #8 ·
Thanks- I had the dealer get a software patch/ flash from Mercedes- but still doesn’t work. Really strange. I just want my brake lights to work. So much work for something that with other vehicles is plug and play

 

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I am having a similar issue with my gls550. I just had a oem hitch installed at a nearby dealership - when I went to hook up my trailer with incandescent lights, the indicator lights, running lights and flashers work but the brake lights do not. The dash shows a brake bulb error. At this point, nothing will work LED or incandescent.. it goes into error mode and states: B1BE2-1C Input circuit 30 (charging cable) has a malfunction. The voltage value is outside the permissible range.
At this point, LED and incandescent will not work and the trailering controller system needs resetting in the vehicle.
The trailer wiring is fine - does not do this to American or Japanese trucks…only my Mercedes.

Any ideas????
 

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Discussion Starter · #10 ·
I am having a similar issue with my gls550. I just had a oem hitch installed at a nearby dealership - when I went to hook up my trailer with incandescent lights, the indicator lights, running lights and flashers work but the brake lights do not. The dash shows a brake bulb error. At this point, nothing will work LED or incandescent.. it goes into error mode and states: B1BE2-1C Input circuit 30 (charging cable) has a malfunction. The voltage value is outside the permissible range.
At this point, LED and incandescent will not work and the trailering controller system needs resetting in the vehicle.
The trailer wiring is fine - does not do this to American or Japanese trucks…only my Mercedes.

Any ideas????
From one of the threads linked above, the factory supplied cable had a pin in it that was not correctly seated. Dealer corrected the issue by fixing the pin for the brake lights.
 
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