I have a 91 Dodge 4wd Cummins that is driving me bonkers with electrical problems.
First off and MOST serious,,,the blinkers and brake lites suddenly quit working(and YES I checked the fuse). They dont lite at all,,no how,,,no manuel blink at all.
Secondly my heater fan doesnt defrost or blow anything,,,it used to work on low,but think that quit also.
Thirdly, my radio and clock doesnt work except when it darn well feels like it ,,mostly on dry cold days. this has been going on for about a year,,,sometimes try to turn off radio with radio switch when it does make noise,,,cant turn it off at all. On this one somebody told me "maybe" it is in the key switch,,,which seems to be gummy and not return quite right.
CAn the other things be switch related also?? This was a country truck,,,not a crystal clean CITY truck!!!
And now its darn cold working in a snowbank on the driveway!!!
I have seen ignition switchs sticking between the run and crank position causing a loss of accessory power, but stop lamps are not usually routed through the ignition switch. The directional and brake lights use the same filaments of the bulbs. Check the bulbs. Check for power to the sockets with a 12v test light not a DVOM. If your tail lights work, then the ground wire in the harness is ok.
I'd also check the chasis and body grounds. Also look to see if all of the wires run in a common harness or area, you could have pinched and corroded wires.