'05 ML 350. I installed my trailer hitch today, I used a draw tite hitch for the ML and purchased the factory wiring harness and factory 7 prong plug.

As per manual I installed and connected the main connector to the brake module and turn signal inicator plug. The lights do not come on on the trailer...

The manual shows on extra connector, which does not seem to go anywhere and the part I received from MB does have two extra connectors next to the brake and turn signal connector.

Am I missing a module? Is there maybe a fuse I need to install?

I am about to go and pickup my new boat and this is all keeping me from going. Any help would be great.

Thanks, Sab.

__________________
regards,
Sab.
'07 ML320 CDI (398 ft lbs / 1400 RPM)
'02CL 500
'91 928 GT Supercharged

Sab, hard to troubleshoot your problem, my trailer light problems have always been GROUND connection problems. If your picking this boat up during the day time, I have done that with no brake lights, just to get it home. Never has been a problem. Your choice, just a suggestion..

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Rich

1990 300CE
71 Chevelle SS 454

After completing the installation instructions included in the trailer hitch kit, please insure that a 25-amp fuse is installed in position F18 in the fuse box (F1).

I don't know if above is the souce of problem or not.

thanks,
the lights seem to work, but no indicator or brake light.
I placed a fuse in 18 and no change.

Searching the forums I found a post suggesting a relay is needed somehwere.

Is it possible the two empty plugs on the new harness need some sort of relay or modulator?

regards,
Sab.

__________________
regards,
Sab.
'07 ML320 CDI (398 ft lbs / 1400 RPM)
'02CL 500
'91 928 GT Supercharged

anyone has any info if I need a relay somewhere?

__________________
regards,
Sab.
'07 ML320 CDI (398 ft lbs / 1400 RPM)
'02CL 500
'91 928 GT Supercharged

Just a thought, it's hard to see when backing up a trailer with a ML. If possible, I try to open the liftgate before backing a trailer. Good luck with the light issue.

OK, it is finally working.
It seems that the parts guys are not familiar with the tow package parts. Since I purchased the hitch elsewhere and wanted only the harness and any parts needed to get the electrical part to work, they had no clue what parts to sell me.
Repeaded call always went in the direction of ... "well, if you are installing it yourself, you are doing something wrong" or "the problem is you are using a draw tite hitch".
I escalated the issue to the parts director and he got a tech involved. Tech stated "all you need is the harness and plug it in..."
Well, I pointed out that the manual shows a piece, looking like a module with a clip on it and my harness had only an empty plug.
The parts director was so kind and made some phone calls. He got me the missing module and it now works. He actually gave it to me for free.

Just thought this might be helpful for someone that expiriences the same problem. The harness needs a seperate brake and indicator module to work.

regards,
Sab.

__________________
regards,
Sab.
'07 ML320 CDI (398 ft lbs / 1400 RPM)
'02CL 500
'91 928 GT Supercharged

I just installed the OEM tow harness on the 2002 ML 500. The turning light and the brake lights are not working. When I turn on the parking lamp and headlamp, all the lights on the trailer lites up but the turning and brake lamp still don't work when I press on the brakes. Could it be the harness or ?

Sounds like you have the same issue then I had. Does the harness have the brake and turn module plugged in?

__________________
regards,
Sab.
'07 ML320 CDI (398 ft lbs / 1400 RPM)
'02CL 500
'91 928 GT Supercharged

You got something for free from a MB dealer. Quit pulling our chain.

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2009 CLS550 55,000
2004 ML350 144,000
2004 X5 95,000
2002 X5 165,000
1996 320S 155,000 (sold)
1991 190E 192,000 (sold)
1989 300SE 160,00 (sold)
1984 300D 210,000 owned since 85, (sold)
1984 300SD 160,000 (sold)