1986. courtesy , dome , underhood lights won't work as well as the door locks, Warning buzzer for key in, lights on etc also don't work. Tried to trace power and ground but can't seem to find problem. Any suggestions will be appreciated

Was it all working and just stopped all of a sudden or? Guessing you have checked all your fuses to make sure there good?

check the fusible links down by the starter.

Thanks, I will check fuseable links. All fuses and circuit breakers check good

http://www.elcaminocentral.com/showthread.php?t=27190&highlight=wiring+diagrams

take this with you when you check it out.

I will check further over the weekend.
Does the warning buzzer control box on the "convience center" have to be working in order for the above lights and functions to work proper;y?

I have checked fusible links. All OK.
It appears to be a problem between the fuse panel and the "convience center" or with modules pluged intp conveince center.
Still loking for a solution

Fusible links check OK What a poor location for fusible links, but GM knows what they were doing.
Does the warning module on the convience center have to be working in order for these other lights, etc to work

When I bought my El C I was told that the fuse box may become a problem because it needed to be grounded properly and that due to being a good area for rusting I may have problems. Is it true that the box needs to be grounded? I've been slowly losing all my accessories (but not the headlights & radio so far). Lost the wipers, the turn signals and the horn.

I know of no grounds on the fuse box. The biggest problem I have seen on the old glass fuses is the contacts get rusty and don't make a connection.
Here is a thread on fixing the rusty connections.

http://www.elcaminocentral.com/showthread.php?t=29737

I haven't had a need to try doug85 tip on prepping the metal for solder yet but it sounds good.

A good place to look would be your directional/hazard switch. check the wiring diagram 86-1 from the link above. looks like at least a few of your circuits share a path through that switch. jumper appropriate power or ground to the wires in question at that switch (power probes are a gem for checking switches, relays, circuits, fuses...ect. best $60+- you could spend for electrical diag).