Help! Trailer lights not working and need to move a boat... - PeachParts Mercedes-Benz Forum

sab · #1 04-21-2006, 06:12 PM

'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.

Early Bird · #2 04-21-2006, 07:49 PM

Quote:

Originally Posted by sab

'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.

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..

Ron in SC · #3 04-21-2006, 07:56 PM

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.

sab · #4 04-22-2006, 02:13 AM

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.

sab · #5 04-23-2006, 11:31 AM

anyone has any info if I need a relay somewhere?

#6 04-23-2006, 12:11 PM

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.