As the title says, brake lights don't work but markers do. Checked the bulbs and their polarity, replaced the brake light switch above the pedal and added a separate ground to each brake light and nothing!! If it's a ground wire I figured adding one in would make it so I don't have to go through the harness. Anybody have anything else I can check? 🙏🏼

 

Have you tested for power/grounds at the sockets? At the brake light switch (power on B+ side, continuity across when depressed)?

Check the fuses in the PDC. Don't have a 98 FSM but the 97 says Fuse 22 (15a), The 99 says Fuse 23 (15a).

 

Yes, yes and yes. Sorry I forgot to list those.

 

Okay I can't post pics but when I stick the dmm down the center wire and lean it over to the white wire, the brake lights come on. Ground is good and I'm getting 11.5v to the white wire.

 

Fixed, chased the wire harness down and had a loose connection under the hood!

 

Well done!! Electrical issues can be toughest to diagnose while sometimes being the easiest to repair.