Brake lights and headlights dont work confused 1998 s10 2.2 4 cylinder recently changed underhood fuse block

More info would be helpful, but just going on what you said, I would guess your brake lights fuse is blown. The running lights and the brake lights are on different fuses, and when you turn the headlights on the rear running lights turn on as well, which you may be confusing with the brake lights. If you check and the fuse is not blown, I suspect you may have changed or had the brake lights changed recently and the bulbs were the incorrect ones. Hope this helps.

If any light lights up when you apply brakes, then the brake switch is ok. The problem could be a fuse and/or a relay. or the bulbs. Those bulbs are dual filament so one filament could be bad, for stop or tail lights.

For the low beam problem, Swap relays 45 & 46 in the underhood fuse panel. Relay 46 is for the Low Beams. If that fixes the light, replace the relay that cam out of position 46.
Since the high mounted brake light is working, that indicates that the brake switch is good. You need to check the bulbs in the rear tail light assembly, if they are good, check fuse #34.

Get a schematic and trace out the power source to those devices not working.

Fuse #2 10A in underhood fuse box. Also, there's a tail light relay. Check that as well

make sure the previously replaced bulb was the correct one and is installed correctly. it is a short between the tail light circuit and brake light circuit, this could even be a faulty bulb or bulb holder, the cruise will cut out if the brake light comes on, even if you dont touch the brakes

I read over the recalls and they do have recalls on brake and turn signal lights but not the low beam headlights while driving at night.

Sounds like the relay or headlamp driver module relay 46, for the headlights is going bad, though.
Or, it could alternatively be bad grounding of wire somewhere or bad wiring in general.

I would check in the underhood fuse box for the relay and see if wiggling it to ensure a good connection helps matters.


Underhood Fuse Block 4.2L Engine Except Saab Underhood Fuse Block (2002 - 2005 Early Production)

Underhood Fuse Block (2005 Late Production - 2007)

Saab Underhood Fuse Block (2005)

Underhood Fuse Block (2005 - 2007)

5.3L Engine Except Saab Underhood Fuse Block (2003 - 2005 Early Production)

Saab Underhood Fuse Block (2005)

Underhood Fuse Block (2006 - 2007)

5.3L & 6.0L Engines Except Saab Underhood Fuse Block (2005 Late Production - 2007)

if both lamps dont work a common problem was the headlamp module. It looks like a black relay in the underhood fuse block (next to the master cylinder), there is two black small relays right next to each other (they used to say 15016745 on top in white letters.) One is for the low beams and one is for the fan clutch. Swap them and check the lamps - if the come on, go get a new one at the dealer and replace the bad one. If you leave the bad one in the fan clutch your gas mileage will be bad and your ses light will come on.

I had the same problem and they found a pin in the underhood fuse block weak and had no contact with the hun nodule. removed and replaced the underhood fuse block.......now today i have no lights on the shift stick so i will be back in there....