Reverse Lights on Manual 280SL won't go off

[Bonnyboy]

I cannot figure out how to turn my reverse lights off. 

I have a 1969 280sl with a standard tranny.  All the info I found on the archives is for automatics. 
I am thinking that the reverse light switch may need to be replaced / massaged but I have not been able to get my hand up there yet. 

Has anyone had this issue and know what to check, which wire to wiggle or what to do? 
Do I need to remove the tranny to replace the switch?

Ian
 

[George Des]

Sounds like the pin on the reverse light switch may be stuck in the closed position. In order to remove you need to get the car up on a lift or high enough that you can get to the upper part of transmission where you can get a wrench on the switch.  Unscrew the switch and see if the pin is in the closed position. There should also be a metal seal under the switch. Sometimes if this is left off the clearance between the pin and the actuator may be close enough that the pin remains in the closed position all the time. I have the same problem on mine but I have a ZF 5 Speed and it uses a slightly different switch. I'm using the MB switch right now and the clearance is too wide so I can not use the metal seal ring. I've recently been able to get the original ZF switch and it has an additional pin extension to ensure that the actuator can activate the switch.

[pagoden]

Greetings, Ian -

From my point of view those are some excellent questions; my problem was the opposite: no reverse lights.  We've ended up looking in some of the same places.  My transmission is away for the summer, so the investigation is on hold here.  One thing I can pass on to you is that though it may look like it, the reverse switch you see up there in the shadows does not  have a circular black plastic push-on connector attaching the wiring to the hex-sided metal switch body you see screwed into side of the tranny.  Put another way, do not  put a long, wide-bladed screwdriver up there to pry the apparently push-on type connector away from the switch.  Because it's not a push-on, not really a connector in the sense that it's attached permanently to the reverse switch, making up an assembly including the screw-in mechanical switch, the fitting attaching the wiring and the ~2 feet of wiring over and down to a connection with chassis wiring to the rear of the car.  It can be pried off but you wouldn't like the results.  And you probably don't need to ask me how I know.  If I had waited until my transmission was out of the car - - it was run with 90wt. gear oil in it by PO(s?) and even though it was changed soon after I got it, finally packed up and spun a bearing, necessitating an overhaul - - I might have seen from the intact assembly how it all goes together.  As it is, I can say that the switch threads in conventionally and there's no way to remove the wiring from it without destroying the 'connector'.  It looks to be at least moderately inconvenient to remove/install on the car, what with that 2-foot pigtail of sheathed wiring (and with an actual, not fraudulent, connector on the end) to pull 'round and 'round in the limited area.  It sounds like George has provided the kind of information you need once you have gained access.  Just please don't use the approach I chose ... the pieces I gathered up were too small to make much sense of.  

I probably should post this in the 'Dumbest Thing I've Done to My Pagoda' thread; where is that thread, anyway?    

Wishing you a smoother passage,
Denny

[Naj ✝︎]

Hi, Ian,

You can access the switch from the small cover (6? screws) on the right side of the transmission tunnel.
Denny's warning still applies. The wiring is part of the switch. There is a male/female plug clipped to the left chassis leg where the switch wiring can be disconnected from the main harness.

Naj

[Bonnyboy]

Thanks all for your advice

I lifted up the floor mats and the tranny tunnel cover carpet etc and found the access panel with 6 screws
I followed the wire from the reverse switch to the connector and ... found only one wire and it was bare in places with no insulating material. 
I snipped the wire and after close scutiny realized that the two wires were fused together. 
I cut back the wires until there were seperate (4" towards the switch and all the way into the wiring harness next to the fuse box in the other direction.

The reverse lights finally went out.

Next I am going to check out the switch to see if it works and try to figure out why the wires melted together.   I am thinking that the meltdown happened by the wires being next to the high beam kickdown switch and getting kicked over and over.  There was what appeared to be a glob of melted tar more than normal right near the switch.   

And best of all... I found a new area of rust-through on the firewall that was covered by the sound deadener material.   

[Bonnyboy]

I got my big wrench and unscrewed the switch.

Denny,  you said I wouldn't like the results if I pried the top of the switch off...but didn't say what the results were....so I pried the top off the switch and realize what you meant - for all reading this - the switch is not servicable - the little allen screws on top that peek through the holes do not undo - I repeat they do not undo.  They are soldered to the connection I think before the switch is put back together and glued together with tar which becomes brittle and is not servicable.

As it turned out my wires were melted together all the way to where they entered the switch so no great loss - my switch was hooped. 

So I ordered a new switch, new connector, new pins etc all from the Mercedes shop down the road - quite reasonable I thought. 

Now to wait for the new switch to arrive from Germany and weld in more floor pieces in the meantime.

Ian