elec. help

[lemagoat]

Hey eveyone got a ? and hope someone can lead me in right direction, about 2 monthes ago I took my ragtop for a drive and as soon as I turned on the headlights the car died! no juice wouldnt turn over, no lights, wouldnt jump, nothing, well we pulled the wire from the starter and replaced some bad wires all the way to the batt. drove the car for a month only during daylight hours, well then did the same thing, turned on the lights...dead again, where should I start this time? dont think the same thing would work? any ideas? what's causing this? dimmer switch? let me know.
Brad

[HOTROD64-STOCK69]

Did you replace the ground wire?

[lemagoat]

Yes I did

[HOTROD64-STOCK69]

Something in the main DC supply is being interupted by amperage draw. Once my brother had a jeep with the same problem. Turned out the bolt for the block ground was to long and seemed to be tight but the connector was not. It would drive down the road to the exact same distance and then just die. Did you test it with a different battery?

[Mark B]

You don't say what car this is, but is there a fusible link in the harness. Somewhere you replaced last time? A short in the light wiring that only has power with the switch on could blow a fusible link and the system would have an open circuit.Try jumping across the solenoid with a screwdriver to see if it will turn over. Exploration with a VOM could help narrow it down too. As Mike said a loose connection (most likely on the ground side) would do what you describe too, check between battery positive and the engine block for continuity. Even a poor connection on the battery itself would do it.

[HotRodTodd]

Just a thought - it sounds like a voltage drop. This can happen on the positive or the ground side. You said the first time, it happened while driving? I would think the main battery cables are OK, because it wouldn't crank or most likely would show up as "the dash lights came on, but when I went to crank everything went out". It sounds to me like you may want to take a close look at the bulkhead where the wiring harness goes through the firewall. The fuse links on the starter (make sure they are installed!) provide the power to the headlights, fuse box, etc. and it's a likely spot for corrosion, etc.
Try this - if you use a test light (a DVOM doesn't have enough of a load to do some of this type of testing), and the lights aren't working/car won't crank - first, connect the light across the battery to make sure it works. Then, find the wires that come from the starter to the bulkhead. carefully probe the wire at the engine side of the connector - if you have power, go to the inside of the car and probe the same wire (may need to move the fusebox). If there is no power, separate the connector and you'll find the problem. If there IS power, keep the test light on the wire and turn the headlamps on - if the power goes away, that is a voltage drop. You can confirm it by again going to the engine side and having someone turn the lights on again while probing the same wire. If it stays lit this time, the problem lies in the connection.
This type of voltage drop testing can also be done with a DVOM, connecting one lead to one end of the circuit (the wire from the starter) and the other lead to the other end of the circuit ( on the same wire - the meter will be in parallel) when turning the circuit "on" the meter should not read more than about .2 to .5 volts
Sorry if I'm rambling, but it's hard to stop me once I get going!
Good Luck and I'll check back in the forum, or you can contact me directly.
Todd

[lemagoat]

first off thanks to everyone who has replied, well last night we hotwired the car, hooked wire to poss side of batt to the poss of the coil, car fired right up with the key, lights also worked turned to key off and car kept running, that's the only way everything works. just an update. didnt have alot of time last night.....ignition switch?

[G6T8O]

Yes it does sound like the switch!
!

[HOTROD64-STOCK69]

Ahh yes the ignition switch. It's a '67? I'm most familar with the '64-'65 stuff but the switches are the same. After you replace it open the old one up. You will find the contact points burnt and the bakelite material burnt. If you hold the switch a little toward the crank direction it will probably keep running. Can you tell I dealt with this GM design gremlin, myself?