help my husband's sanity!

Howdy,
My husband & I have a 1974 CJ5 that we have restored. All was fine until recently when the marker lights started flashing like "hazard" lights (which we do not have) and blinkers will not work independently. HELP! We have checked the ground and tried new marker lights which were not necessary because the ground is good according to the tester.
Hubby is losing his mind.
Any input is appreciated,
Thanks!

 

My guess is that somehow the parking light circuit is shorted to the turn signal circuits. It is possible that the two bulb base terminals are somehow connected on one of the four parking/tail lights lights. Pull each one separately and see if normal function returns. If that fails, start looking at the wires coming off the flasher unit. If this retains its now 50 year old wiring, it is entirely possible some of the insulation is missing. Hopefully less of a rat's nest behind the dash than my CJ's.

 

Make sure all the blinker/marker light bulbs work. Then chase the wires through the junction box on the firewall, blinker switch and fuse box. I replaced the wiring harness in my 1983 CJ7 due to many wire breaks.

 

Electrical is usually a pain in the ass. Step 1, get a decent multimeter, ie. Fluke. The process is tedious but the only way to find the issue is to test each circuit. If it's all the marker lights, I'd start at the fuse box for the marker lights. Youtube has some pretty decent vids on how to chase a short and/or ground fault.