84TAVeRT Posted August 16, 2009 Report Share Posted August 16, 2009 my alternator light on my 68 521 has started staying on until you get high rpms... this started after the truck set for a couple of months without being started... i was thinking alternator, but could it be the voltage regulator ... where should i start... thanks, Chris Quote Link to comment
Cuts metal like mad Posted August 16, 2009 Report Share Posted August 16, 2009 Take the alternator out and get it test... if its bad, upgrade to and IR alt. If its good, get a volt regulator and wait for the alt to fail so you can upgrade. :D or just upgrade NOW! Quote Link to comment
flyerdan Posted August 17, 2009 Report Share Posted August 17, 2009 It probably just needs a set of brushes, mine will sometimes flash with the turn signals. AutoZone has them listed, probably have to order them. Quote Link to comment
ggzilla Posted August 17, 2009 Report Share Posted August 17, 2009 Most common cause: worn alternator brushes. If it's the stock 1973 alternator they are easy to replace and only about $5. You can remove yours first to confirm if they are worn. * Left: worn down to the limit line * Right: New Quote Link to comment
datsun8 Posted September 1, 2009 Report Share Posted September 1, 2009 When the brushes go bad, that's totally symptomatic. CSK has a 50 amp for like 50 bucks, it's all you'll ever need unless you have a system or somethin. Quote Link to comment
hang_510 Posted September 2, 2009 Report Share Posted September 2, 2009 where should i start... check all the electrical connections, esp the grounds. ...then R&R Quote Link to comment
84TAVeRT Posted October 8, 2009 Author Report Share Posted October 8, 2009 well we took both alternators for the 73 and 68 to autozone... they both tested good... so we swapped the voltage regulator from the 73 to the 68 and it worked... i have ordered a yellow accel coil and a replacement voltage regulator... so we should be good to go this weekend :D later, Chris Quote Link to comment
ggzilla Posted October 8, 2009 Report Share Posted October 8, 2009 Thanks for following up. Now we know a bad regulator can cause this symptom. I'm having a problem my alternator light comes on only when the headlights are on, but goes away at high RPMs. Quote Link to comment
datzenmike Posted October 8, 2009 Report Share Posted October 8, 2009 Maybe one of the three diodes are bad. This would cut output by at least 1/3. I wouldn't doubt the lights would turn the charge light on when the output is only 20 amp at mid range revs. Quote Link to comment
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