Brake lights not working on one side? Are there two relays

How about your flashers and turn signals? BTW welcome to the group!

Help to know what Barth you have.

Grounds bad on the side that is not working.

Year:: 1988
Model:: Regal SE
Length:: 31
Engine:: Ford 460
Chassis:: John Deere

The above is from you profile Todd. Find a good ground and check for power. On your John Deere Chassis, do you have brake lights separate from the turn signals or do the break lights flash (blink) the brake lights when the signal is on? You may be able to hear the flasher when the left is working to find the flasher location to check other connections.

I have schematics and experience with the Regal GM chassis, sadly little knowlege of the Ford/John Deere setup.

In addition to the local grounds, check for any rogue wiring for a trailer light harness, etc. I have seen splices that failed and both coach and trailer lights went out.

Sorry for not being more responsive. Busy weekend, on the road a lot. Actually still on the Rd heading to VA. It is an 88, 31ft Regal SE on a John Deere Chassis. The break lights are part of the flashers/ turn signals and the turn signals work fine, so I think the ground is OK. There's a hitch, and it looks like at one time some had a trailer plug wired, but it's been taken out, so it could have something to do with that. I didn't get to spend much time on it this weekend. I'll try to find the relays next weekend. Thanks for all the advice. If I get it fixed I'll let everyone know what it was. I think I'm going to be spending time on a bunch of wiring problems.

My daughter had a 1 ton Ford (maybe) van of that era and it seemed there was a relay in the rear panel for each brake light. Long ago and fuzzy.

Welcome to the world of Barth. The good news is that for the most part I have found that the OEM Barth wiring in the coach itself is pretty good. (One exception, in the 90's they used splices in the 110V wirng. These were subject to failure.)

OTOH, the chassis wiring (in my case the GM stuff) is pretty bad. The headlights were dim because the voltage at the light socket was only 10.5. I have replaced wiring in the light circuits, tail light wiring and fuel tanks. Also the engine wiring and alternator harness.

In general, the GM wiring is almost always too small. 16 gauge headlight wires... I would consider 14 as minimal. The alternator is rated 100 amps, should be a #4 but you get #6, and so on.

Definitely check ground connections. Too bad we don't have more info on your chassis wiring. Good luck.

The GM P30 Service Manual has schematics and also the web has bunches of the GM chassis schematics.

Could be grounds. Looked at documentation on previous work, and ground fixes were mentioned a few times.

I think I would pull the lens and check to see if power is getting to the hot side of the bulb before I did anything. If so then go on a search for grounds.