Chevy brake light short

[wgander]

Where do I start looking for a short?
All of the rear lights on my 1997 Chevy Express van work correctly individually. But when the running lights are on and the brake pedal is applied, the bottom right side light bulb goes out. It works OK when the brakes are applied or the lights turned on, but not when both are active at the same time.
The socket is clean and a snug fit. I swapped the left and right light bulbs, and the right one still didn't work correctly.
Do I have to crawl under the van to check the tail light harness?

[FIRE_UP]

wgander,
You have a PM.
Scott

[wgander]

I'll check youtube. It was raining today so I couldn't do anything outside. It's a conversion van, and doesn't fit in the garage.

[michigan]

I also have a 1997 Express and had the same problem. It's a bad ground. These vans are known for it. I watched a youtube video for a fix. I used a jumper wire from the socket to the body of the van on each side. It corrected the problem and the lights work great.

[Jagtech]

X2....Bad ground.

[enblethen]

Did you check the trailer connector?

[FIRE_UP]

Wgander,
Yep, as has been suggested, it's most likely a bad ground on that side of the vehicle. On most domestic cars/trucks, the ground is the socket housing that touches the outside of each bulb. And, that ground can be connected to the main chassis or frame via a wire or, simply direct connections of metal to metal. A good test would be to piggy back a wire along side the brake light bulb as you insert the bulb back into the socket. But, make sure the tip of the wire does not touch the contact points on the bottom of the bulb/socket.

Then, connect that other end of the wire to a good ground. Then, try your lights and see what kind of results you have. If your lights now work correctly, then it's a matter of correcting the ground problem with that particular socket.
Scott

[wgander]

Yes, I wrote that in my original post. All of the lights and sockets look good. The left one works correctly, that's why I swapped left and right light bulbs.

[enblethen]

Did you look at left side?

[wgander]

The bulb and socket look good.
It's just the one light bulb that is supposed to work with lights and brakes. Where to start looking for a ground?

[Dr_Quick]

To me it sounds like you may have a ground problem. If when you turn one light on and another gets dim or goes out it could be a poor ground.

[enblethen]

Check out your trailer connector.
Check out left side tail and brake lights.
Sounds as though a socket or lamp filaments are short.