Alternator light not working - Help
 

Hopefully an easy issue here, I hope.

I have heard that the if the alternator warning light does not come on at all that the wire is broke and will not charge the battery.

I have a semi new (this summer) battery and no alternator light will come on at all.

So I am figuring the warning light wire is hosed up somewhere in there... The Haynes manual of course is no darn help on this at all.

Thanks for any input you all can give :)

I *think* the battery and alt are still good since the light will not come on. My two guesses are that warning light and maybe the regulator.

Thanks,

When you turn the ignition key to on the light should come on. Once the car starts the light goes out or in some rare cases flickers dimly (usual cause loose belt or idle to low).

>the alternator warning light does not come on at all<

When fully powered up and sitting with the key in the AUX position the light does not come on at all. The green oil pressure light comes on just fine, but not the ALT light.

Agian there is something with the wire going to the warning light and I am not sure how it works or what connections need to be checked.

Thanks,

if the brushes in the alternator don't touch the commutator, because they're worn out, the circuit will not be completed, and the light won't work. it could also be the bulb. ground the blue wire either at the bulb, or at the regulator, or alternator and see if it lights. probably not a broken wire.

Let me try and rephase what I just read...

If the bulb is bluwn then the alt will not charge?

If the brushes are not hitting the comminicator the light will not come on and the alt will not charge. Granted the brushes part is pretty obvious of course. Granted I doubt this is the issue as I would *suspect* that before the brushes wore down completely it would lead to a flickering ALT light situation as the alt lost its power generating capability.

... Very well could be the bulb. What a lame system if this is the case. Are we sure Bosch designed this system or did Lucas :)

John, I thought you had a bus already? Real hippies drive Westis! Surfers drive 21/23 deluxes ;) LOL

Thanks,

I just looked at the wiring for the 82SC on the pelican parts web site. I know it might be a little different but the principals are the same. From what i can see this is how I believe the circuit works. On page3 (page2) 12 volts is supplied from the battery to the igition switch and contact 15 supplies this voltage to page 5 (page1) to one side of the alternator light. The other side of the alternator light goes to page 1 (page 1) to terminal D+ on the voltage regulator and the D+ on the Alternator. Since the gererator is not turning and generating voltage it becomes a path for a ground source hence the light lights. With the engine turning the alternator eliminated the ground source and generates 12volts and supplies 12volts at the D+ terminals. This voltage is feed back to the alternator light providing equal voltages on both sides of the light hence light goes out. If the battery is supplying 12volts and the D+ terminals are supplying 10volts then there would be a 2 volt difference across the bulb hence a low flickering light. I might be wrong but that is how I see this circuit working. A bad bulb will have no effect on the Alternator /Voltage regualtor generating a voltage. Now if your bulb doesn't work and you break the fan belt. The alternator light won't come on and your engine will overheat and probably die a miserable death.

I can't explain the reason, but John Walker is correct..if the bulb is bad the alternator "system" will not charge ..and yes...it may indeed be just a bad bulb or bulb connection. I'll check my archives and report back with a more complete explanation, if I have the time.
---Wil Ferch

I had the same problem with my 66 the blub was bad Changed it out and has worked fine ever since

Wil and J.W.

Yes your right The battery voltage supplied to the D+ terminal of the voltage regulator provides the voltage at terminal Df to the alternator creating a magnetic field and generating output at the B+ terminal. Now I see that if the bulb is blown (no output from Alternator) The D+ terminal on the alternator is provided voltage from 3 small exciter diodes in the alternator once the engine is running.

Do not assume that the alternator warning light will flicker when brushes are going bad. Just this past summer my light gave me no warning at all until my car died on the way to work with a drained battery and no functional alternator. Sure enough, brushes were toast.

Update:

Changed alt light warning bulb.... No dice. I hate when the simple fix does not work :(

Turned on the car by jumping it with my truck. Checked the voltage at the battery cables and found nothing, well 12.75 which is just draining the truck battery. A working alt will give 13+ volts.

I next looked for the voltage regulator... Found it mounted on the left sidewall of the engine area. But not connected to anything...!? Could not find any wires that sould go to it either. So I figured it had been replaceed somewhere along the line and an alternator with a built in voltage regulator installed. So out comes the alternator, amazingly easy.

So now I have the alternator out and I guess just need to go get it checked out and so forth. I could not see the brushes and I have no clue what to do with it after this point... So off to some shop it will go.

The alternator is stamped "Made in France" so it probably surrendered.


Thanks,

I have an alternator/Voltage regulator R&R article in the Pelican Tech area that may be of some help...
---Wil Ferch

http://www.pelicanparts.com/techarticles/911_volt_reg_replace/911_volt_reg_replace.htm

Good stuff Wil!


Thanks,