Will crank but not start if you short across starter relay. Power to lights, wipers. No power to instruments or radio. Does nothing when ignition key is turned. Where do I start troubleshooting?

 

what engine, what transmission?

 

4

460, 5 spd manual

 

first thing i would do is check the clutch interrupter switch.
also have someone watch for movement of the clutch master cylinder when you step on the clutch pedal.
quite a few of these trucks had a defect in the firewall that would allow it to crack around the clutch master. then when you step on the clutch pedal, the master cylinder would shift and the interrupter switch would not make full contact causing a no start situation.

 

Ok. It is really hard to push in clutch