Also the only fuse that ***** the lights down is m20 and that on the diagram just goes to the upper back switch so what does that have to do with my lights?
There is no way I can know without having my own source for that diagram, because the image is such low resolution that I can't see what anything on it says.
I see, I tested the tail light wires and they gave 12v coming out when the ign is on. With or without them plugged in
It has been a long time since cars were made, on which the lights were controlled by simple switches. On these cars, when you push a button, you are just telling the BCM what you want to do. The BCM then opens/closes relays, mosfets and switches to make the lights actually happen.
Here is just a quick example of how this can be an issue, without be being privy to Ram's actual programming. So, just a wild-assed guess.
When you first switch the ignition the BCM boots up and goes through a power-on self test. The only way it can know that a bulb is out is by passing a voltage through the circuit, and measuring the resistance in the circuit. The same reason why all those lights on the instrument cluster come on when you first turn it on. It can only check for function and measure by sending voltage, like a multimeter. If the BCM thinks there is an incandescent bulb in the circuit, it sends the appropriate voltage for an incandescent bult. For the sake of argument, let's assume that someone replaced the incandescent built with a LED. It's is possible that the BCM's POST (power on self-test) incandescent bulb measurement voltage is enough to illuminate the LED, but when the BCM sees very little resistance, it thinks that the incandescent bulb is burned out and gives a message on the instrument cluster.
There are lots of possibilities. Maybe a previous owner installed LED's, and made the appropriate changes with AlfaOBD or Jscan. Then traded it in at a dealership, where they updated the trucks software, resulting in the BCM getting re-flashed it to the OEM specs. Then the dealership sold it to some other used car dealer. Or, any number of other possibilities.
That's whey it's so hard to diagnose a bunch of aftermarket stuff. Because we aren't privy to how Ram programs everything and how the computers react to aftermarket parts. It's so much easier to diagnose problems when everything is stock.
