What color is the ACC check valve? It should be on the forward firewall ahead of the brake master cylinder. A line from the vacuum pump hits the forward firewall, goes into the check valve that's clipped to the firewall, then splits into a line that goes into the cabin and a line that goes to a vacuum reservoir. At least that's what the manual says. I just noticed that there's no check valve in my SDL, just a connecting bit of rubber tube. For that matter, I don't see the line that goes to the reservoir.

The check valve in my 91 300SE is yellow. I'm wondering if the SDL uses the same kind of check valve so I can widen my search.

The silly thing is that it's probably a $2.00 item at the dealer and I'll pay $5.00 for it at a scrap yard

Thanks,
Sixto
91 300SE
87 300SDL
83 300SD