'87 5KCSQ finally attacked by electrical gremlins:-(

[Duncan Thomson]

I don't have lot of experience with the electrical side of things, but this
sounds like some sort of electrical grounding problem.
The clue here is that a number of bulbs are activating all at once with
differing intensities.
I would check your main ground connection to the negative battery terminal
and then check the wire which should come from this point and head through
the firewall. It is quite likely that the problem is under the dash since
work was done here, and it is the dash lights which have been affected.

Basically a poor ground at one bulb will cause it to ground the the path of
least resistance whic is often via other bulbs and connections causing these
bulbs to partially illuminate.

It is also quite possible that your battery needs replacing as well but I
can't see this contributing to the problem...
A poor ground at the battery however, may prevent it from charging
properly...

just a few thoughts

Duncan
(mechanical engineer, NOT electrical!)