Hello all.

I've been putting off resolving a door lock/unlock issue for about a year, which is about how long I've had the 1980 300SD. But this weekend, with a fresh supply of connectors, plugs, check valves, and rebuild kits, I decided to tackle it. I methodically checked lines starting with the main yellow to driver's door. No vacuum. As difficult as it was accessing it from under the dash, I was able to disconnect the main line from the check valve and found a split from engine bay to valve. Vacuum was good from valve to door. It was no small feat connecting a new line from this position.

Next, tested the lock/unlock circuits. Both held vacuum but only the unlock function worked. I checked the passenger door and could easily get the actuator to lock and unlock with minimal vacuum. Strange. I went back to the drivers door and applied vacuum to the locking circuit. It finally worked once my vacuum gaged approached 23 on the dial.

So I checked my vacuum coming into to switch and it would build up to 20 after a few seconds. I thought maybe the system needed to "charge". But after idling for 5 minutes, and trying to unlock and lock the doors, I still could not get it to lock. Back the manual to see if I'm missing something.

I've read through it in detail prior to beginning and referred back to it along the way. But something about this time made me look a little closer the vacuum switch information. It mentioned adjusting. At first I thought the inner rod was the adjusting point but then realized it was the mounting bracket.

The sun had already gone down but I figured this was an easy test with a headlamp. Slid the body to the point shown in the photo and boom! I can now lock and unlock the doors!

I though I would share this in case someone overlooks this little adjustment as I had.

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John V
1979 300D
1980 300SD

Thanx ! .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

The beginning of a happy new year!

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84 300D, 82 Volvo 244Gl Diesel