Tail lights on my 2000 chevy venture arent working. i replaced the multifuncion switch, but it didnt help. any advice on this could help. thanks

While trying to troubleshoot a problem with the right front headlight, I reached up under the dash- just left of the steering column and found one of the wiring harness that come through the firewall-- I gently moved the bundle aside about an inch and because the turn-signal flasher was pretty loud I decided to see where it was real quick (damned hard to find - way up in there vertically behind the gauge cluster -- couldn't see it ). Anyway, flasher found- now guess what-- The friggn headlight starts working--- now we are afraid to touch the wiring bundle. Every fuse is good and there is power across each fuse so apparently the problem lies between the switch and the wires going to the rear lights . I may have to replace the headlight switch as well , or remove it and do continuity tests (ohm meter) but I don't know if this will solve the problem. Drivetrain and AC , ease of driving , handling in this Venture Extnded van are good--- but the electrical wiring problems seem to be a Plague with these lower-line GM vehicles as well as some of the more expensive GM stuff (example- my ( '95 suburban LT with fuse block, powerwindow wiring, and rear AC controls wiring issues ). I've noticed a quality problem with Most of the electrical switches in the car including the rear windshield washer / wiper switches which I actual took apart and reassembled (works perfectly now ) . They look to be of cheesy quality (meaning I would Not install them on a yugo much leass a GM product) but I guess thats a Quality issue huh? I may install a standard headlight switch without the autofunctions and re-wire to the rear and to the headlights if I have to (have done it before but what a colossal pain in the rear to get what should be critical basic wired parts (headlights and taillights ) to work.

While trying to troubleshoot a problem with the right front headlight, I reached up under the dash- just left of the steering column and found one of the wiring harness that come through the firewall-- I gently moved the bundle aside about an inch and because the turn-signal flasher was pretty loud I decided to see where it was real quick (damned hard to find - way up in there vertically behind the gauge cluster -- couldn't see it ). Anyway, flasher found- now guess what-- The friggn headlight starts working--- now we are afraid to touch the wiring bundle. Every fuse is good and there is power across each fuse so apparently the problem lies between the switch and the wires going to the rear lights . I may have to replace the headlight switch as well , or remove it and do continuity tests (ohm meter) but I don't know if this will solve the problem. Drivetrain and AC , ease of driving , handling in this Venture Extnded van are good--- but the electrical wiring problems seem to be a Plague with these lower-line GM vehicles as well as some of the more expensive GM stuff (example- my ( '95 suburban LT with fuse block, powerwindow wiring, and rear AC controls wiring issues ). I've noticed a quality problem with Most of the electrical switches in the car including the rear windshield washer / wiper switches which I actual took apart and reassembled (works perfectly now ) . They look to be of cheesy quality (meaning I would Not install them on a yugo much leass a GM product) but I guess thats a Quality issue huh? I may install a standard headlight switch without the autofunctions and re-wire to the rear and to the headlights if I have to (have done it before but what a colossal pain in the rear to get what should be critical basic wired parts (headlights and taillights ) to work.