[79fox]

when the car is running and i turn on the headlights sometimes they work but the idle drops but, Sometimes when i turn them on i lose ALL electrical power i mean all the gauges stop working. The tach (i only have stock) goes out i have no brake lights or turn signals.....But if i rev the engine pretty good like 4500 5000k its like a miracle and i get ALL the power comes back does any one have ant ideas on whan this could be? any suggestion would be helpful thanks

[fogged306]

Check all your grounds first. Battery to chassis, chassis to block, ect. I would also put a meter on your battery and see what the voltage is at while it's idling and what it's at while idling with you headlights on.

[DEFIANT]

Battery not holding charge and not supplying enough power to electrical components.
Might be the alternator as well.

[94bossgt]

you need an alternator its not a miracle your just spinning it fast enough for it to work a lil bit

[95tbirdv8]

if it just started doing it all of a sudden, its most likely your alternator, or the wire from the alternator to the starter solenoid

[Stdyhand]

Got to agree with 94boss. It sounds like an alternator or a voltage regulator. It doesn't sound like your getting enough power until you increase the RPM's. Take the alternator to a parts store and have them test it.

[79fox]

it does not get slowly brighter like is was loseing power. Its like someone hits a switch and everything works even at idle and will work fine but sometimes if i turn off the headlights and try to turn them back on all the power will cut out again and somtimes come back on when i rev it or it takes a couple trys and then works again.
I am thinking it might be a loose ground somwhere that i am knocking loose when the motor shakes i dont know why the power cuts out when i turn on the headlights and the motor does not move at all. does anyone have any ideas?

[fogged306]

A poor connection somewhere will do this. It will support only so much current and when you ask to much of it all of a sudden (turning your headlights on), it just fails. Usually a loose ground will do something like this, like I mentioned before. Have you checked them yet?

[79fox]

thank you i could not explain it better myself. i checked the (big ones) going from the battery to the block and there is another one going from the block to the firewall but i was iffy with this one i was not sure if that is the proper place for it and is there any smaller grounds that would cause this problem?

[Ohsplat]

since you have a 79 have you switched to a newer style alternator? If not you have a lot more wiring to check over then a 86+. You have a external voltage regulator and that itself can be shorting out.