i have a 1985 Ford fullsize Bronco with a 5.8L 351 carburated. Now the problem isnt the alternator because ive replaced that and this problem still occurs. heres whats up , it will start up fine and run strong it idles high but not my problem at the moment. but as soon as you turn the lights on and leave them on then shut them off wait a few minutes as if waiting for the alternator to recharge the power, and then shut it off and try to start it back up , its as if the batterys dead.

i think its either a bad light switch , or maybe some bad wiring

somebody help me out

 

I would look at the connections for the ground at the battery.....in fact make sure all your connections are clean and tight. Also check the terminals....for corrosion.

 

I would look at your battery, is it new or can u change out one with another vehicle? When arriving home from work one day i got back in my truck 1992 bronco) to start it up and NO START. I checked the battery, and it read on my fluke 12.5 volts, clicking bad. Got it started once and read 14.7 volts as the alternator was charging and wouldnt crank again. I swapped it out with my 85 f-150 battery(being curious) and it started right up. Culprit- battery :which read good . Looked at my paper work and the battery was 3 mos shy of being 6 years old. Battery was a Motorcraft in which i swapped it out with the same brand TR