Morning. I have a 1986 Vanden Plas I inherited and it has some electrical issues - still working to figure them all out. I've been told that the wiring harnesses on these are mediocre and problematic. True?
What things should I look for first in this type of car? Common problems areas and types?
Also, if I need to replace the wiring harness what is the best route/product to take?
Thanks.

 

The vast majority of electrical problems are causing by dirty/loose/corroded connections and grounds....and corroded fuses. Harness replacements are very seldom required...except for some of the engine bay wiring which gets so heat baked that the insulation breaks off.

The general rule is to never replace any electrical parts without first cleaning the connections.

Here is some good info that will help you along. Some of it, I think, also appears in the sticky threads at the top of this section

XJ FAQ

Cheers
DD