i have a 85 trans am,and one day i go to drive it at night and the headlights came up and on but then they went off and i lost the radio and horn and everything else was fine.the car ran and everything.so a few days later i go out and the headlights work and radio and everything.so i go to start it and nothing.it would not start.then after about a week i go out there and it starts and no headlights.can someone please help me with this.thank you!
This is hard to diagnose over the net, but here's where to start. All the power for the electrical system comes from one main connection (after the battery of course!), your positve cable goes to the starter and then the power wires go from there. Check the connections at the starter, not just for tightness, disconnect and clean them and check the fusible links ( the soft, flexible feeling wires with an eyelet on them that goes on the positive starter stud, they may be melted). If all is ok, follow the harness up around the back of the block and check for chaffing, shorts or breaks. also check the connections at the alternator, the power wires may split from there instead of the starter post. Also check the main wiring harness plug at the firewall below the brake booster to see if it is loose. After that it's all inside and could be at the ignition switch on the bottom of the steering column (not the key switch, the actual electrical switch bolted on the side or top of the column near it's bottom end) or get a wiring diagram and check for power and ground as necessary. I know this is vague, but I think it's likely at the starter connections. Sometimes the conection is good enough to start and then the accessory connection goes away, and sometimes there is just enough connection to run the acc. but not to start the engine. Also check the ground connections at the battery, engine and firewall. Hope this helps.
A little help... 'cause we don't all have to learn the hard way!
I have a 68 Firebird that has similar problem. Starts ok, but no radio, wipers, horn, heater fan, back-up lights, some dash lights & one head light. Do have a dome light & key buzzer(yippie!) Brake lights & turn signals are ok. Dash & head lamps, probably just need replaced. When pressing the horn button on the steering wheel, you can hear the relay click, but no sound. I replaced one of the horns, but still have no sound. Thanks for the advice about checking positive connections in & out of starter.