First pass door would not lock, then all doors, now car will not turn off!
 

1979 300D.
My small vacuum leak has now gotten out of hand. Its my fault for not fixing it sooner. My question is, how do I take my pass. door apart, and once it is apart, what am I looking for? The first symptom was that when I engaged the drivers door lock to lock all doors, all would lock except the passenger. I would manually lock it. When I unlock all of them with the drivers door lock, all would unlock.

Now the only door that locks is the drivers, and the car will not turn off when I turn the ignition off. I have to pop the hood and pull up on the throttle linkage to the IP.

Any help is greatly appreciated.

Disconnect the yellow vacuum line under the hood where it enters the firewall and plug the front end. (keep golf tees in your glove compartment for this purpose) All will be well, but you'll have to unlock/lock your doors manually. Fix the door system leak(s) at your leisure.

This will allow me to turn the car off?...(so I pass inspection this month:)
Just plug the yellow vac line with a golf tee?
Any more detail on the passenger door leak? Once I get it apart, what do I look for? I have a handheld mityvac, but no idea how to really use it.

I am not sure about a 79 SD, but my 86 SDL has a manual engine shut off valve inside the engine compartment. Look for a lever that says "Stop" or something to that effect.

Mine has that too. That is what I have been currently using to shut the car off. But when i go for inspection, I doubt that will fly. I'll start with plugging the yellow vac line, and then take the door apart.

You may want to just unplug the line in front of the yellow check valve and plug that line.

the point Kerry is making is that if you have a vac leak at a door, it interferes with the vacuum engine kill. So isolating the laek with a golf tee should allow the vacuum to kill the engine. If the leak is upstream of the (brown I think) vacuum tube that goes to the UFO shaped kill switch, then you are out of luck and must replace the line from the vacuum pump.

But based on your description, it sounds like removing the door licks from you vacuum circuit will restore engine shut off function.

Popped the hood. Can't find the yellow vac line.
I got up under the steering wheel, and can see a yellow, and a yellow/brown line coming thru the firewall into the cabin...but on the engine side, the lines are so dirty, I can't find the right one.
I took the passenger door apart, where the leak first started, and I have a Yellow/red and yellow/green line going to the dual pod thing that controls the door locks. Can I plug one of these lines here? Which one?
Could the dual pod thing that controls the locks be leaking too...not the line? The two pods fill and empty with air when I pull on the metal rod connecting to the door. Also, when plugging the line, should I be removing the line from the rubber connecting sleeve, or removing the sleeve with the line still in tact and plugging that?
All I am trying to do here is pass inspection, so I can fix this problem correctly later...so having the ignition turn the car off is all I'm trying to achieve at this point. I want to get this out of the way so I can fix my exhaust next. Are the window switches a requirement for passing inspection? Add one more thing to the list if it is....ugh.

buy a hand held vacuum pump at Autozone or whatever. I would get a nice metal one if you can find it, you need one for this car, thern start pulling a vacuum on your lines until you find the one that leaks, fix or plug it. since you have the door apart pull a vacuum on the two sides of the actuator. if the actuator is bad, replace it or plug the line, if it is not then you have a cracked hard line. you will need to trace it back under the plastic tracks on the floor

simplest solution to pass inspection is to clean the lines under the hood with some solvent like mineral spirits. The yellow line should be obvious with a little cleaning to the lines just right of the brake booster kind of above the oil filter.

Like in the pic.
I used a new connector with one fewer openings.

I think the yellow/brown line you found is for the vacuum shutoff valve on the IP.