The 85 300d has this black box in front of the shifter 83 does not

The second cube thing has a red #10 fuse pluged into the red head of it and has 4 prongs and what looks like a vacuum port

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ohh ohhh I know that cube!! I plucked it out of my car earlier this week! its some sort of voltage regulator tied into the EGR, and I am assuming the ECU it is easy to find on ebay and such.

I dont know about the black box tho....

Ahh the cube -is it the OVP? I could not find it in the under dash electro gizmo parts stash.

The cube is the OVP relay.

From reading about that thing earlier it also has to do with the AC working or not on an 85-or /also had to do with the tach signal running thru it so if 85300tdt plucked it out is his car still running-and whats not functioning?

Your question looks like it has the answers in it already.

Actually, that black box is for the seatbelt tensioners. All 1985 cars got them as standard equipement. Notice how the seatbelt buckles say RS on them? That stands for restraint system. That box has the crash sensor in it which sets off the seatbelt tensioners. It is mounted in the middle of the car on the transmission tunnel so it can detect crash forces properly. It gets its power from the overvoltage protection relay. The EGR computer also gets its power from the OVP, and the tach is run off of the EGR computer.

The seatbelt tensioners take up any slack in the belt, so in a crash the belt "catches" you as soon as possible giving it more time to work. It also tightes up the reel so the belt doesn't unwind as much as you are held back by it. Yet another reason why the 1985 W123 is the one to have!

-J

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