The cruise amp is located behind the trim panel, also known as the kick panel, on the drivers side of the car, below the dash. You will have to remove this panel to gain access to the amp.

Possible to save yourself a lot of grief...
 

If your fuses are more than 3 years old, REPLACE ALL OF THEM!! It doesn't matter what they "look like", replace them all! Would you rather spend hundreds of dollars on a "possible fix" instead of $6-7 on a "possible fix"????
As you replace them, take some fine emery cloth or other mild abrasive (pencil eraser works too!) and clean the contact area before replacing the fuses (ONE AT A TIME, THANK YOU VERY MUCH!!).
Then you can take an air hose (low output pressure) and blow (or a vacuum and suck)any residue out of the fuse panel/box before latching the cover back down.

1987 300d cruise control question
 

Can anyone explain why the rear lights have anything to do with the cruise control? Mine's inop, I've been searching through here for a fix. I did rewire my rear lights since I bought a set of european style and didn't realize they were'nt the same... Lights work fine but cruise isn't. I don't think it's related but I've been told different.

Asfar as skill level I'm about a 7 on a 1-10 scale. Any help would be appreciated.

Right now I would like to know the relationship between both of them.

My Tach and my cruise control went out at the same time sooo, sooo well there I am.

my 86 amp. is under drivers side also there are different amps they are color coded, the end of the amp is different colors mine is orange

the taillights are the ground for the cc system

I think you mean the brakelight bulbs. To fully understand the the wiring, you'll probably need a wiring diagram for your car. My 380SE is simpler than my 560SL, which has a bulb status monitor in the circuit as well.

I'm surprised no one has mentioned re-soldering the amp. Lots of threads on this subject, so I'll just note that I re-soldered my 380SE board twice, and only got good results 1/2 the time. The 560SL had a bad actuator, which I tested following the GDL site procedure, so I replaced it, and the faulty amp. with a rebuilt one off EBay. I'm still looking for a good price on a rebuilt one for my 380SE. The older ones without the 'coding plug' are getting hard to find rebuilt.

Expect to pay a lot for these components, new or re-built. IMO, it may be much cheaper and easier to buy an aftermarket cruise and wire the control stalk into it, so the only non-original stuff will be under the hood. There's a thread or 2 on this as well. http://www.peachparts.com/shopforum/diesel-discussion/219993-official-audiovox-ccs-100-install-thread.html

Brakelights are the ground for the cruise control, if the lights aren't the proper resistance, the cruise won't work. The idea is that the lights receiving 12v will cancel the cruise (no ground).

If you lost your cruise, tach, and ABS at the same time, you should be looking at the OVP relay which is a red-top relay with a fuse on top, behind the battery, along the side of the ABS and engine computer.