Alternator help!!

[schary]

My voltmeter was registering 12 volts at the battery while the engine is on.. The alt light glows all the time.. I replaced the alternator, figured it was time, and the problem still exists.. Went to a shop and the guy measured the connections at the ext voltage regulator (he jumped the two and measured the third ) and said the alternator is charging well.. So at his recommend i put in a bosch voltage regulator and guess what? Still just 12 volts at battery with light glowing.. HMMM.. Any ideas on this, I figure the alt is fine and wired right, but not sure where to look..
Thanks for any help on this..

[boxsterman]

I'd suspect your wirings to the lamp. The lamp normally turns off when both sides have equal voltage. Maybe the charging side wiring is loose or floating to ground.
Is it on when the engine is not running, but the ignition key is turned?

[bell]

ground strap? check it for corrosion as if it's got a weak connection can keep it from charging (on internally regulated alts for sure), it's located at the front right side of the tranny and bolts below the torsion tube......

[schary]

I will check to see if its on.. I do know that there is a charging problem, could the lamp cause a problem? I have measured voltage at the battery and it seems low...
thanks

[schary]

I will check that strap.. I attached it not long ago when we installed the engine, but maybe its worked loose... Another guy said it might be the starter connection? Thanks so much guys..

[boxsterman]

You can generally tell if the system is charging or not by comparing the voltage at the battery.
The voltage should be slightly higher (and above 12 volts, maybe 13+) when the engine is running compare to engine not running at all. And voltage should go higher when you rev your engine to 2500 - 3000 RPM compare to just idling.

Also check your current drain with everything off (engine, radio, lights, etc.). It should be less than one AMP. This is to check if have a big leak in your system...making it hard to charge or keeping the charge.

[schary]

Voltage seems the same if its running or not.. I pretty much know its not charging, or charging low.. Not sure of the cause here.. Are there wires I should check first? Is there a voltmeter test to rule things out? if anyone has any tips please let me know
thanks

[boxsterman]

Sounds like the charging wire is disconnect to the battery. Unfortunately, I don't have the schematic in front of me to tell you where to probe. I believe the charging wire also goes to the lamp; it's probably not connected to the lamp, which would explain why it's on all the time.

[joetiii]

Has this ever been resolved?

[willf]

if the ground straps check out, check the battery health, maybe old dying battery? Can you slow charge the battery and get it to hold more than just 12 volts? Llike mentioned, the voltage at battery and voltage at the alternator have to be consistent for the light to go out when the engine is running. If the alternator is doing its thing correctly, and the battery is not keeping up, I would think the light would stay on because the two never really equal one another... quick test might be to connect a different battery that is fully charged/ known good and see if that light turns off.

[dsmyth]

This may not be what your looking for but I have an 85 where the light was staying on and it was the diode behind the light that was not functioning. When the diode was replaced the light went out.