I have a 2005 Journey with Suburban SF42 gas furnace that does not come on. The problem began when, in the the middle of a heating cycle, it shut down and would not come on line. No heat or fan. According to the Suburban troubleshooting guide, there is only three possible causes. 1. no voltage at the unit. 2. a bad relay 3. a bad motor. After extensive investigation I ruled out all of these but in the process I found a bad solder joint on the PC board right at the point where the 12VDC supply connects...