Weird electrical

[Rattlenbang]

Before I start chasing my tail looking for shorts etc, I've got a very strange problem that just started. Whenever I brake the backup lights come on, as well as when I hit the left turn signal. The dash "R" light comes on and it beeps faintly, just as if it was in reverse. Anyone ever experience something like this?

[Growlerbearnz]

Bad earth on one of your tail lights, probably the left. I'm guessing that when you brake, the backup lights come on about half as brightly as usual.

[Rattlenbang]

That's true. So bad earth??? How does one get a bad earth in just one light? I've never had the light cluster apart, never having had to replace a bulb in two years.

[Overlanderjay]

Probaly corroded connections Rust never sleeps

[Growlerbearnz]

All the tail light bulbs' earths are joined together on the back of the tail light housing, then that one earth wire (black) goes to the connector along with all the power wires.

As Jay says, the usual culprit is corrosion in the connector- I scraped the blades clean and filled mine with grease last time it corroded, and it has been good ever since.
It could also be a break in one of the multiple connections on the back of the tail light housing, but that's unlikely since they're pretty well soldered together.

What's happening in your broken left side is that the power being applied to the brake lamp can't get directly to earth the usual way, so it's going through the left side backup lamp into the right side backup lamp, and then to the right side's earth. The break in your earth has to be between (or at) the connector and the lamps.

Just for reference, here's what happens on the chassis side of the connector:

Once through the connector, the left and right earth wires connect again, ending with a ring terminal screwed onto the body, one on each side of the van. The right side earth terminal shares its screw with the washer motor. The screws *can* corrode, but if one goes then all the tail lamps will still earth properly through the remaining one.

While you have the lamps out I'd be cleaning up and greasing the earthing screws, the connector terminals, and all the lamp sockets. It gets pretty gross back there.

Good luck!

[Rattlenbang]

Thanks so much for this!!! Turns out it was much worse than I thought. Not only the backup lights and beeping, but when one turn sigfnal is on the other one is as well, just not as bright, and if the brake lights are on they both flash with the turn signals. It was a real light show back there! But as you said, a bad ground on the passenger side. I would have chased that bastard forever trying to find the fault, as it was so crazy. This forum, and the people participating, totally rock.