Problems with Charging System

[Shane]

The other day, while driving to work, the alternator on my GN seemed to have given out. As the dashlights dimmed, I began to monitor system voltage on my Scanmaster, and it fell all the way to 7.2 VDC before the car finally died (I was in the middle of nowhere at 4 am).
After a tow, this weekend, I took a look at it. The alternator has a brown wire that goes into a clip into the alternator that had been previously cut and taped back together, only to have fallen off now. I figured that this was the sense line, so I fixed the wire, and charged the battery.
The car ran fine, except for one thing.
System voltage stays at ~10.5 volts, rising and falling, until the alternator "catches" and the system returns to regular operating voltage. It does this for no apparent reason. Independent of road speed, engine speed, etc.
Any thoughts?

 

[Crazi]

Double check your wire as you are right. That wire is what causes the alternator to charge. I also believe that they have to reach a certain rpm before they begin to charge for the first time. After that you are ok like you describe.

When you notice this again, rev the engine to 2000 or so RPM and see if it "catches." Or you could get it tested and if it is bad, then just get a impala ss alternator. 6" case and 140 amps. My voltage is almost rock steady at 13.5!

 

[Turbo Brian]

That brown wire goes from the back of the alternator, under the brake master cylinder into the body connecter where it mates with the other connecter half containing the brown wire inside the car. If the body connecter is loose or the pins are not making good contact, you will have charging problems. The brown wire inside the passenger compartment connects to the plug that connects to the back of the instrument cluster.

If the alternator checks out bad, replace it. If it is good, it is not too hard to pull the instrument cluster, splice into the brown wire, and run that wire through the grommet into the eng compartment to the back of the alternator to bypass all of the problem wiring.

 

[Shane]

Turbo Brian-
I think that might be the problem, it seems to catch better after I have hit a bump or something. I don't know. I'll look into it. Anything else I should know?

 

[Turbo Brian]

Also make sure that the volt light comes on when you turn the key to the ON position (motor off lamp check). If that lamp is burned out, the alternator will not be excited and will not charge.

 

[dpok69]

The brown wire gives of 12 volt signal to let the alternator charge. The volt idiot light is right smack in the center of that signal wire. So if the bulb (acts like a resistor) burns out it will not complete the circuit. Some people like me have a resistor behind that socket in case of the bulb failure.

But still, if the socket is not making good contact with resistor or not, the brown wire does not get the 12 volts.

Try this since someone has already clipped your brown wire. Remove tape and seperate the two. Put tape on the wire that leads to the passenger compartment to prevent short (actually if it gets grounded it will light up the volt light inside the car if bulb is good). Get another piece of wire and tape it to the wire that leads to the plug on the alternator.

Use the other end of the wire to attach it to a 12 volt source. You can temporarily connect it the black fuel pump prime connector by the alternator. If it helps, add a 1k ohm resistor to the the wire also. See if that helps. Read more about this at alternator help

Right back with your findings.

 

[GNVenom]

Related topic was in this forum. I posted some comments along with the Casper's fix:

http://www.casperselectronics.com/c...cgi?search_request_button=yes&keywords=102032

This will assure proper charging of the battery under abnormal conditions such as the VOLTS light circuit malfunctioning.

Check out the "INSTRUCTIONS" link...it explains it pretty well.
-John Spina
http://www.casperselectronics.com