From what the stealersh- I mean dealership said, non-electronic malfunctions will not be read on anything but the factory provided computor. The shop I took it to, a large body shop-repair facility has a top-of-the-line scanner and it showed no faults. The self-test on the 2001 Wrangler involves depressing the odometer button and turning the ignition switch on and it showed no stored faults. BTW, the guy at the dealership had never heard of this self-test function on the vehicle.