No start or crank 93 ch 350

[usrjcro11]

This is describing and solveing a problem. Truck started cutting on and off going down road after starting up and going about a 2 mile. Tried shutdown override and did not help. All gauges looked good and radiator full. Truck finally quit completely. Started testing with power probe cab relay and starter relay on firewall and would turnover. Disconnected positive battery cable and was getting 12 volts on cab relay with key off on negative side. My multimeter was shipped to fluke for repairs. I said it must be a capacitor somewhere that hasn’t completely discharged. Hooked farm service truck to truck and lowboy and ran air hose to services tanks on truck and pulled it home about 2 miles because getting dark. Next day remembered I put negative firewall relay on other truck but could not explain 12 volts. Took relay off 91 model and installed on 94 model. Went to hook up positive battery cable and found problem. Crossover positive cable   had rubbed on battery box and had gone to ground. The ground relay had done its job. That explained 12 volts on negative side of relay but probably few amps knowing all I had was power probe on battery. 
Live and learn. Simple things first.