1999 Chevy Venture

Check both of the rear lights there is a short in one of them or both. This is where your trouble is. Could be a bulb melted in the socket or melted board. Common problem with ventures, silhoettes, montanas. You are just following a beaten path followed by many others that bought g.M.'S junk.

Replaced both tailight circut boards with new ones wires where not hot or look burned but now when you turn the sterring wheel the back heater speeds up and slows down as you turn

Don't know why turning the steering wheel would make the heater change speeds. I can find nothing in the wiring schematics that would let it do this. Does it only do the steering wheel /heater fan speed going down the road or sitting still turning steering wheel or both? If going down the road it could be a loose wire on the rear blower resistor or a bad resistor. You have to get inside the left rear side panel the resistor is on the end of the blower motor. It will have a plug connector going to it and should be two bolts holding it in place

Yea I know it has me stumped to so I decied to replace sterring colum with a used one from junkyard when I went to remove the junkyard one I noticed that the main dash "ground" is connected to the top right mounting bolt of the sterring colum so hopefully it's that I will found out tonight if not then I'm really up creak without a paddle thanx agin for the help

The rear resistor could be bad if the steering column don't cure it try the resistor. Good luck with it.