Hello, I am new here. I'm having a hard time with my truck. The #9 fuse, which controls the dash lights, parking lamps, tag lights and rear running lights. I have replaced the fuse twice now; it is supposed to be a 20 amp. there was a 25 amp fuse in first, and when that one fried, I put a 20 amp in. That one didn't last even last three days. The one I have in now is a 30 amp fuse. The other thing(*) I am having problem(*) with is my check engine light. It says that my O2 sensor, and my brake switch are insufficient. I have already replaced my O2 sensor twice in the past year and a half, and the check engine light is still on, and it is still saying bad O2 sensor. I don't know where the brake switch is.

the brake switch is right above the petal. what specific code number is the o2, there are a ton? as far as your prkg lmp circuit must be an intermittent short, i would never recommend putting a bigger fuse, good way to start a fire. i would take apart the front and rear housings. could be getting wet. the rear is the most problematic on all the 88-98 trucks. sometimes the bulb is in wrong or not all the way can also cause shorts

Which housings are you talking about? And where is the bulb you are talking about?

the rear tail light, and front running lights are on that circuit as well as the plate bulb, could be any one of those

P0140 HO2S circuit insufficient activity bank 1 sensor 2
P0719 Brake Switch circuit - low input
I have looked at my parking lamps and it might be my corner one

did you replace it with a decent brand, those o2s are pretty picky? inspect the wires? also has to have 12v on the heater circuit to work properly

if you sign up for auto zone you can look up the circuit diagrams and see what color it is and the brake switch wire to the pcm, unless it has to do with taillight problem

That'* his downstream sensor. Either its a lazy sensor(dead) or the cat is clogged. But, I'll lean towards dead sensor because you will be having drive-ability issues if the cat was clogged.

there is a different code for the cat because it reads how many switches it does, when they go bad they switch less, when the cat goes it reads different. i have heard since gm puts the window so tight on everything it has to be a delco, delphi, or bosch, the cheap ones go out of the window quickly