Hi all,

Bought new switches for the upper console (rear light, sunrrof, emergency, antenna, and rear defrost) because they were worn out. Pulled the ashtray, the radio, the panel with the switches, and disconnected the switches.

So now I want to replace the light bulb for the fiber cable. I see where they all join way up in back, but how do you get to it?

Looks as if I need to remove the climate control unit, but what the heck holds that in? There is a big bundle of wires or something going across the top of the climate control unit as well.

Any hints on how to change this bulb?

While I'm in there, anything else I should do before I button her up?

Lastly, I bought window switches too. How does that trim come out? And I need to replace the bezel at the shifter; how does the shifter handle come off?

Thank You
Fred

If you think of it as an octopus, there's a wire that leads into the head. Pull that wire and the bulb will come with it. It takes a gauge cluster type bulb.

I don't know if the ACC control panel has to come off. Mine comes off pretty easily after the radio is out. I don't remember any screws. I don't remember many things

The big wire bundle probably plugs into the ACC control panel.

Not much to do back there except check the ACC center vent actuator. At that all you can do is check.

With the ashtray frame and radio out, lift the tray ahead of the console trim. Pry the bezel from the console trim and slide the console trim forward. You should be able to get the switches.

I don't know how the shifter comes off but I think a lock nut is visible when you lift the bezel.

Some of this information might not apply to all 126 models. As you can tell from my sig line, I have my hands full

Sixto
91 300SE
87 300SDL
83 300SD

Sixto
All that worked just as you said. Found a couple of the little lights melted into the plastic of the climate control, so I could not replace those. All the rest replaced and working. Switches all done too.
So I changed the oil and filter too.
Start the car up to check for leaks - now it won't turn off with the key!!! Turns off fine with the stop lever on the pump.
Now what did I do?
Fred

Join the club! You probably knocked a vacuum line off while you were in there. I did it on my 81 300SD.
I now have a vacuum leak somewhere in the climate control, so you have to turn it off to shut off car. My other half says I have to fix this tomorrow. She refuses to raise hood to shut off. She turns key off, locks doors, goes in to work. Then comes back in 15-20 minutes to see if it died.
Hope this helps, Jeff

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As mentioned, check the vacuum hoses. You might have knocked something loose while changing the oil filter.

If the ACC vents work, I mean anything but defrost, and you can't shut off the engine with the ACC system off then the problem probably not a vacuum leak in the ACC system.

Look for the red line with a green stripe going into the cabin in the area of the brake master cylinder. Cap that line on the engine side and you've isolated the ACC system from the engine vacuum system.

Sixto
91 300SE
87 300SDL
83 300SD

AARGHHHH...

So I go in to the dash to change some switches and bulbs. As you read above, now the engine won't turn off on its own. Well, now I find central locking no longer works, and heat only comes out of defrost vents. I must have a big vacuuum leak somewhere.

I used to hear the vac pump in the trunk run when I worked the locks with the key - no more. I pulled it out of the trunk. I hooked up my mighty vac to the yellow line, pumped it to 17 inches and it stayed there.

Hooked up mighty vac to engine vacuum and get about 17".

I did not see any vacuum lines anywhere near the ACC unit when I pulled it out to change bulbs.

I pulled the vac lines off the injection pump - no sign of oil leakage in any of them. With the engine running, I hooked up mihty vac to the shut off port and she turned off with minimal (maybe 3") vacuum applied, so it is not a leaking diaphragm there.

I did a search on this forum, but am not finding a step by step procedure to track it down. Can anybody point me to the right thread? There seems to be plenty of knowledge out there on this, but what I've found has not helped.

Are there vacuum reservoirs? Where are they? How do i isolate them?

Thanks
Fred

OK

I pulled the brown tubing off and pumped her up. Holds vacuum, and with vacuum applied, car shuts off.

Pulled the red/green line, pumped it up, there is a leak somewhere in there. Plugged off the connection at the engine side and she turns off, but still no locks and vent control.

Where does the red line go to first? And where after that? I can hold no vacuum no matter what I set the ACC to-off, vents, heating, cooling, no fan, auto fan, high fan.

At least I can drive it this way, but its a nice day here in frigid Wisconsin. Good day to tear things apart in my unheated garage.

Any ideas what to do next?

I'll search the archives too.

Thanks
Fred

First thing - on a 126, the vacuum circuit for the locks is independent of the rest of the vacuum systems. No vacuum line for the locks goes near the dash except at the kick panels.

Sounds like you knocked the main line to the ACC vacuum switch bank. You might be able to get to it through the ashtray, radio, ACC panel cavity but if you don't know the system well enough to feel your way, you're better off getting to it the right way.

Remove the carpet in the passenger footwell. Remove the right kick panel. Pull towards the center of the car then towards the rear. Lower the passenger lower dash panel. I think it's 3 screws hidden in the carpeting right under the glove box, a screw hidden by the kick panel (now visible) and a plastic quick release screw that takes a quarter turn by the transmission hump. The lower dash panel should come off now with some AC ducting. Remove one screw in the carpet at the forward edge of the transmission hump side panel. Pull the panel forward to release the clips at the rear end then move it out of the way.

You'll see a black vertical strip with 6 or 7 vacuum lines leading to it. The vacuum line on top is the feed. I suspect that's what got knocked loose when you were replacing the octopus bulb. If not, find the bad one with the MightyVac. A couple of them have crossed lines so if you find one that leaks, plug the others and try again or trace it to the actuator and check downstream of the splitter.

There are no vacuum lines connected to the ACC control panel per se. There are vacuum lines that run across the dash right behind the ACC control panel in the area of the octopus.

Check all the fuses before futzing with the door lock system. Check means pull it out and tug on the terminals. With age, the fuses develop cracks you can't see when they're in place. If you haven't changed the fuses in 10 years, repleace all of them now regardless of how they look. You're talking under $3 from FastLane.

For the locks, the blue wire should see +12V when you lock the driver's door by key or manually, the yellow wire should see +12V when you unlock the driver's door by key or manually. If that doesn't happen, you have a bad switch or a bad wire.

If the pump is getting power, you should feel vacuum at the outlet when locking and pressure when unlocking.

Pull a vacuum on the actuators from the trunk. If the doors lock, it's pretty safe to say there's enough system integrity that they'll also unlock. If they don't unlock, happy hunting for the bad actuator.

I hope this helps.

Sixto
91 300SE
87 300SDL
83 300SD