'91 300SL 3rd brake light removal

[Benz Mondi]

I first did a search, but couldn't find the info.

How to properly remove the trunk lid liner?

I don't want to snap off a fastener or break something needlessly.

The lens on my 3rd brake light seems to have warped and is now letting the rain or water from car washing in and collecting in the liner. When I open the trunk lid, the pooled water comes cascading down and into the trunk.

Thanks,

AL

[Benz Mondi]

OK, I discovered that the panel is only held in place by standard panel fasteners. First issue done, but of course others cropped up...

2nd issue: warped outside lens. Is the only remedy for this a replacement of the lens or is there some other way to make the fit rain tight?

3rd issue: light strip will not light when properly connected.
I took out the light strip, removed the bulbs, properly cleaned the strip, checked the continuity at each bulb socket and at the plug (all 000's), tested each bulb with direct power to make sure each lit up, inserted the bulbs into the strip and applied 12v power- all the bulbs lit up. Started the engine and tested to make sure my brake lights were working (blew the #5 fuse, turned out to be a coincidence that resulted in a 30 min. delay as I went through the fuse box cleaning each socket and replacing each fuse with new copper ones- was on my list anyway). Brake lights work. Reconnected the light strip (without installing it in the trunk lid)... brake lights still come on, but not the 3rd light strip. No power to the wire.

What else can do before I take my trunk apart to trace the wiring?

(of course I thought this was going to be a 15 minute job replacing some burned out bulbs... what was I thinking?)

Thanks,

AL

[Chris at Pelican Parts]

Al-

It's a known problem that the third brake wire (located on the right near the trunk hinge) is prone to being cut/worn over time- it's just a bad design on MB's part.

I ended up removing all of the trunk lid wiring trying to track down the issue and found that someone had already done a poor repair job (twice). I decided to replace everything with a heavily insulated wire as far down as I could comfortably reach with my soldering iron and then wrapped the connection with heat-shrink tubing and electrical tape.

The wire also now sits away from the hinge (which is something I'll probably revisit when I install some better lighting in the trunk) but so far I haven't had any issues in the last six months.

Good luck!

-Chris

[97 SL320]

Originally Posted by Benz Mondi

OK, I discovered that the panel is only held in place by standard panel fasteners. First issue done, but of course others cropped up...

2nd issue: warped outside lens. Is the only remedy for this a replacement of the lens or is there some other way to make the fit rain tight?

3rd issue: light strip will not light when properly connected.
I took out the light strip, removed the bulbs, properly cleaned the strip, checked the continuity at each bulb socket and at the plug (all 000's), tested each bulb with direct power to make sure each lit up, inserted the bulbs into the strip and applied 12v power- all the bulbs lit up. Started the engine and tested to make sure my brake lights were working (blew the #5 fuse, turned out to be a coincidence that resulted in a 30 min. delay as I went through the fuse box cleaning each socket and replacing each fuse with new copper ones- was on my list anyway). Brake lights work. Reconnected the light strip (without installing it in the trunk lid)... brake lights still come on, but not the 3rd light strip. No power to the wire.

What else can do before I take my trunk apart to trace the wiring?

(of course I thought this was going to be a 15 minute job replacing some burned out bulbs... what was I thinking?)

Thanks,

AL

Later cars ( 95+ ? ) had LED lights and no access cover on the right of the trunk liner.

I bought a factory MB lens 2 years ago for my 97 for ~ $ 35 ( I think that the bulb version is different than the LED version )

You might be able to find a salvage yard willing to split up a trunk lid / had a damaged lid where you can replace the lens / change to a LED version. ( No idea if the bulb out system looks at the 3rd light or not, a LED might trip a bulb system.

Have a look on car-part.com , this is a nation wide inventory search of participating salvage yards.

[Benz Mondi]

Originally Posted by CYoura at Pelican Parts

Al-

It's a known problem that the third brake wire (located on the right near the trunk hinge) is prone to being cut/worn over time- it's just a bad design on MB's part.

I ended up removing all of the trunk lid wiring trying to track down the issue and found that someone had already done a poor repair job (twice). I decided to replace everything with a heavily insulated wire as far down as I could comfortably reach with my soldering iron and then wrapped the connection with heat-shrink tubing and electrical tape.

The wire also now sits away from the hinge (which is something I'll probably revisit when I install some better lighting in the trunk) but so far I haven't had any issues in the last six months.

Good luck!

-Chris

Chris, thanks for the tip. Yes, I did find that my wiring seems to have also been mended twice using crimp connectors. I'm going to solder+ shrink wrap better wires in the morning. It seems I'll also have to do a neat job of adding some clear silicone to make the lens fitting water tight. In the process of doing all this I've also had to use a Dremel to cut the head of one of the little screws that holds the reflector housing on. The nut that the screw threads into broke free and was just spinning around. I must say that this is the first time I can remember where I was this disappointed in an MB design. Still a life long fan of the mark though!

[97 SL320]

I'm guessing you didn't see my post above. Lenses are not expensive new.

[Benz Mondi]

Originally Posted by 97 SL320

I'm guessing you didn't see my post above. Lenses are not expensive new.

Thanks for the tip. I'm checking on them now.

AL

[Benz Mondi]

I wanted to give the final outcome of the post I started (not many seem to do this step).

After taking the whole unit apart (lens, reflector housing, and bulb strip), I discovered that one of the three little mounting screws that hold the reflector housing in place against the openings in the trunk lid wasn't screwed all the way in and allowed that section of the lens to move away which allowed water to seep into the truck lid.

Of course, it couldn't be as easy as just screwing it back in because the imbedded nut that it screws into had broken loose. I had to Dremel the head off and fashion a new backing using a narrow plastic Molley and new screw. I went ahead and took the opportunity to remove everything, clean, wax, test all the bulbs, re-install and used a thin bead of clear waterproof caulk I use on my boat to seal everything up. All done!

Thanks to all.