My 2002 Dodge Durango 4WD will not engage. The switch does not light up in 2 or 4WD. The service 4WD light was on until I disconnected battery to remove dash panel to test switch. That was 2 weeks ago and it has not came back on. I took it to the shop and it shows no codes. I'm wondering whether its the switch, transfer case module or powertrain control board?