1998 Chevy Cheyenne The alternator was not charging

Tiny
2CARPROS-ARCHIVES
  • MEMBER
  • 1998 CHEVROLET CHEYENNE
  • V8
  • 2WD
  • AUTOMATIC
1998 Chevy Cheyenne mileage: 92,000. The alternator was not charging I had new brushes put in. Since then, once in awhile the alternator will go to full charge and the lights will get over bright. Some say it is the voltage regulator but we cannot find it. It is not in the alternator and it is not on the firewall some say it's built into the computer. It only does it once in awhile but I'm afraid it is going to burn out my headlights when it does it. Thank for your help
Do you
have the same problem?
Yes
No
Friday, December 3rd, 2010 AT 10:27 PM

2 Replies

Tiny
2CARPROS-ARCHIVES
  • MEMBER
If the alternator armature was not resurfaced at the time of brush installation there is no way for the alternator brushes to mate squarely to the connector ring and inhibiting the operation. Replace the alternator with a top quality unit.
Was this
answer
helpful?
Yes
No
Friday, December 3rd, 2010 AT 10:29 PM
Tiny
CARADIODOC
  • EXPERT
It is in the generator, bolted to the rear housing and there is no way to test it. It's what the connector plugs into. There's no way to sugar-coat it. GM went from the second best generator to the world's worst pile starting with the '87 model year. Disassembling this thing is darn near impossible without breaking the tabs off the diode block. They use special zener diodes too to control the horrendous voltage spikes produced by these units. Once you finally get everything apart and the diode block is ruined, do you hope the regulator is good or do you run the extra expense of replacing it too? By the time you're done, you're better off with a rebuilt generator with a warranty.

It is common to go through four to six of them in the life of the vehicle. What more and more professionals are finding out is to reduce the repeat failures you should replace your perfectly good battery at the same time. The old battery will work fine in older cars, but as they age, their ability to absorb those voltage spikes is reduced. Those spikes also play havoc with all of the unnecessary, complicated, unreliable computers on the truck. The current pulses resulting from those spikes sets up magnetic interference that radiates into other wires in the harnesses and induces voltage spikes in wires for various computer sensors. A lot of engine running problems can be traced to a GM generator that is still charging the battery.

There isn't much else that can cause the problem you described. The voltage regulator monitors system voltage right at the output wire. The exception is on trucks that have digital dashboards. On those it is critical to maintain the voltage feeding it to prevent flickering of the display, so those will have a second wire in the plug on the back of the generator. They monitor voltage right at the cluster, understanding that the rest of the system will be close to that and isn't too critical anyway. That still shouldn't cause the output voltage to rise unexpectedly.

Besides the regulator, it's always possible the braided copper wire to one of the new brushes is rubbing against the metal housing and grounding out. Usually that won't be intermittent, but if the right one does ground out, the regulator will be bypassed and the generator will charge wide open.

Caradiodoc
Was this
answer
helpful?
Yes
No
Saturday, December 4th, 2010 AT 1:59 AM

Please login or register to post a reply.

Recommended Guides