New Summer, New Problems

so pulled out my cabby '91 for the summer, starts up fine but have two minor electrical issues.
First the right rear light isn't working, cleaned the contacts and all other lights are working, the bulb is ok as well.
With a multimeter i only get just 0.1 v, i tried to follow the cable (red/grey) but not sure where it ends up. Any suggestions what i should check next, alos can i piggyback on the left rear light as a temporary workaround?

The next issue is that the speakers on the right side isn't working, only the left side. Get miniscule power from the tweeter or main main door speaker when testing with a multimeter.

I've checked all fuses an they are all good.

Would love to fix this now when I'm ready for some summer driving

firsty thing.  Make a new ground with a large ring connector that will fit one of your rear bumper bolts in the boot.

Attach that to the bumper bolt then run it up to the connection in the middle of the lamp set, you are giving all the lights on your right a new better ground.

See if your lights work yes yeah, bad ground.  No, then use a DVOM.
Tur your lights on and measure the connector for 12v at the center of the lamp holder no.  Then a broken wire some where between the head light switch and the bulb.

Here are how the 90's are wired.



bumper bolt that I add separate grounds to each lamp holder.



lamp holder



For your speakers, take the speaker out and use a 9VDC battery to ground the negative side, and then scratch the other connector to see if the speaker Scratches or pops, if it does it isn't your speaker.

Nex step os to remove your head unit and do the scratch test for the right speaker to verify that your speaker sill pops or scratches.  If it does then you have a bad head unit.  If it doesn't then locate the wires on the inside of your car going to the speaker door flex.  Splice  open  pair of speaker wires and see if they pop or scratch.  open and close your door If they don't power your speaker then you may have a broken wire in your door flex.  Large Pain in the hiney to fix so it is usually easier to run new wires fro your head unit connector to your speakers. hint make sure that you leave about 1 foot of wire looped up inside the cabin side so if they break in the future you don't have to rerun the whole thing but can pill it over and splice it inside the door.

Had this happen to my passenger side window motor wire.