I have seen a lot of other things a lot more complicated on this site which were called DIY. On an 84 or 85 (the ones I know for a fact will work) there is only 2 wires and a switch that need to be added. One from the control unit very accessable, atached to the curise ontrol bracket just above the brake peddle and the other can be hooked to any ignition power such as the lighter socket in the ash tray. The control unit for this system has a 6 pin connector with only 4 wires used. The one used is a white wire and can be spliced into. The other wire is attached to the lighter in the ashtray which is black/green wire. The switch can be any type of on/off switch that the other ends of the two wires are connected to.
To me this is a DIY project. I realize that I do auto electric work as a living and building a new wireing harness is a DIY for me so each person needs to determine if it is a DIY for them. As far a adding the whole system to another car is a little more complicated but if you go to a PAP and get the control unit and it's harness is doable. I'll be glad to help anyone wanting to try this if I can.

Paul

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84 500 SEL (307,xxx miles)