Ed;
Resistance of a trucks chassis to it's electrical and/or electronic systems is a valuable tool to use in the determination of a truck's electrical cleanliness. A truck can have no or low resistance readings and still be electrically clean. The real problems are created by current flowing in systems and areas it shouldn't be happening. On todays AC vehicle, when they are being used to work in all weather conditions outside may fall short of the 100K ohm you are looking for yet still perform and do their job well. This is often the case in Europe. Low resistance is only telling the tech that there is a potential path for current to flow. What is interesting is when a truck stops working and the chassis has a higher resistance reading then 100k but the current flow is above say 45 mA and the electric steer drops out or transistors blow, particulary an IGBT.