turn lights on 1997 Chevrolet Venture

My turning lights front and back stop working when I step on the brakes

Asked by for the 1997 Chevrolet Venture
I had this problem on my '99 Venture. There were a couple of contributing factors. The first is a failure in the printed circuit boards that the rear lights plug into. You can replace these boards (there are places online that sell them for half what you would pay at the dealer). The other problem is in the pigtail that actually plugs into these boards. I've only been able to find these at the dealer and they were quite expensive, but replacing them solved my problem.

There is a design issue where water will drain down from the tailgate and into the tail light assembly (follows the gas lift cartridges). Because the connectors are on top of the light assemblies, moisture gets into the plugs and corrosion causes them to short out.
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Sorry to see you didn't get an answer to your problem, we get a lot of questions and simply cannot get to them all. Were you able to get the turn signal issue resolved?
Same problem we had with our 2000 Venture. It was the board on the back of the tail lamp and the plug that goes into it. I bought a new aftermarket lamp assembly and a new plug repair kit from GM..