Blinker/Cruise/Brake Snafu

[JohnnyR]

Need help figuring this out on my 2005 GMC 2500HD Duramax. Coming to work this morning with cruise control engaged, actuated the blinker and cruise kicked off. Then noticed that whatever blinker I turned on, the other blinker blinked faintly as well. You can see it in the dash and in the mirror blinkers. If that weren't enough, whenever I apply the brakes, the blinker stops. Stopped to check rear lights w/left blinker on and both right and left were blinking as well as brake lights.

Anyone run into this before. Truck has 63K miles.

[JohnC]

First thing I'd check is the tail light ground on the rear frame member.

[JohnnyR]

I'm going to check that this evening. When I did a search, I found that tip; not necessarily for my exact problem, but bad grounds can do funny things.

[JohnnyR]

Tell me whether what I think is the taillight ground is in fact correct. I could not find a separate ground wire under the vehicle bed. Did find where taillights, license plate lights, and towing receptacle plugs all come together on a plate bolted to a frame cross member at the left rear of the truck. Am I correct to assume that bolt and plate are the ground? If not, does anyone know where it's located? I cleaned the coating off the plate and frame member and reattached, and things are working fine so far. But when I frove home last Friday evening, it worked fine before I pulled and cleaned things.

[cowboywildbill]

It might be the BCM. I had a simular problem with bleed from from a turn signal, that time it turned out to be a stop tail/bulb that somehow was crossing both poles in the socket.
That took a while to figure out. Some rust in there caused it. It can happen in the trailer connector plug. I had one rust out on the inside where the wire connections are. You have to pull it apart, easy to do. That may be the culprit. They get wet in there and corode. Common problem with factory plug.
Just some thoughts.