GeorgeS

I replaced my battery yesterday. I think the alternator is bad because I have 12.65 volts with and without the car running. I should have 14V or so running to keep the battery up right? Any rate I was about to go buy an alternatior and now the car won't shut off... It's not pre-ignition (at least I dion't think so) because it's not chugging. This sucker runs just like the key is still on. What the heck happened?

wattac2

What year car? Need to update you profile.

GeorgeS

1968, 327

...Roger...

There is a yellow wire on the poss. side of the coil coming from the starter solenoid....try removing and operating the car like that and see if it stops doing the running on. If it does stop then replace the starter solenoid.

71 Green 454

Before you go and buy a replacement alternator, you might want to check the date code on the old one. Do you know it it's the original? What are the codes on the old one?

Dave

682XLR8

Your 68 has an external voltage regulator mounted on the inner fender, by the horn relay. Check that before buying another alternator

GeorgeS

I took the alternator in and it checked. It was bad. I am still not able to turn the engine off once it is running. There are two wites on the +side of the coil. when I remove them it turnes off. With both wires disconnected and the key in the off position, the yellow wire has no voltage abd the other wire has 12.5v. The wire is light brown and has cloth around it. I don't know where it goes so I just hooked up the yellow wire and tried to start. It is turning over but won't fire. With the light brown wire on by itself...it runs till I disconnect the battery.

GeorgeS

Once the engine is running, shouldn't it continue to run even if the battery is discunnected?

...Roger...

Now were getting somewhere.It can be that the ignition switch is bad but it also can be some backfeeding through the fuse box also.With the engine running and the key turned to off(engine still running)start removing fuses from the fuse box...if one of them causes the engine to shut off then it would be backfeeding through that circuit.If none of the fuses shut it down its probably the ign switch.

...Roger...

Yes if you have the key turned on but at this time you probably have the key in the off position.

GeorgeS

Thanks Roger. I will mess with it tomorrow. I am tired of looking at it. If the ignition SW is bad, does the dash need to be removed? I was avoiding the dash removal till fall. I will be replacing the spedo and cluster gages over the winter.

...Roger...

I'm pretty sure on the 68 you can remove the key tumbler,then remove the ring around the key and the switch with harness attached should drop down under the dash.Then put it back the same way.

GeorgeS

Roger, Thanks for the help. I did as you said and began to remove fuses till I found the faulty circuit. Bubba was under the dash . Added a wire from the 12v switched side of the fuse panel and connected it to the brakes. I took it off and all is well. Is there a quick way of telling if the alt is charging the battery? Someone mentioned that disconnecting the batt while the car was running could blow the alt.

...Roger...

I've never heard disconnecting the battery would blow the alternator.You can watch your ammeter and turn on your headlights and see if it recovers.You can measure with your voltmeter the battery voltage with the engine off and then measure it with the engine running.You should have around 14v running.

GeorgeS

I have 12.6 running. That is the same as when it's off. This is my second alturnater. I don't know if I am blowing them or there is something else hosed up. Any ideas? Would the voltage reg cause this?

...Roger...

It sure can.The voltage regulator tells the alternator what to do.