its not the solenoid.. Its actually the batteries.. They run a split 24/12v system (CRAP). Alternator puts 24, SMP connections run 24, all other parts use 12v. Theres a stepper transformer next to the batteries, that can get really hot, and start to melt the batteries and cause all other kinds of problems. The other big problem is that the master switch is not a true master like on other SMP, as the 12v system is still live.. You can play with everything in the cab, but not start the truck. The only thing that I think is cool, is the SMP light switch is digital, and not the old switch style... BTW Ours in Edmonton aren't grounded.. They're still doing drivers courses on them right now.