Thanks for the info Arthur. I still cannot figure how to get to the bottom of the fuse box. I see on other posts that you have to go through the dash panel on a w126, I hope it isn't that difficult on a w124. I have taken the 6 screws off the top of the fuse panel (2 at the front, 2 at rear of fuse panel and 2 at rear of relay panel) but cannot get to the bottom of the fuse panel. Is there some kind of secret to getting in there? The red wire comes out of the firewall at the rear of the brake booster and the socket that plugs into it appears to go to the resistor pack. Any idea where to find this wire behind the firewall? That would probably be the best place to splice into it. Would it hurt to splice into it on the harness for the resistor pack? The last few questions would probably be mute if I can find out how to get into the bottom of the fuse panel.

Once again, thanks for all the info you have provided.