Is it the alternator?

demonsvx · #1 08-02-2006, 05:30 PM

My dashlights come on after restarting the car and turn off after revving it a little. This does not happen if the car sits overnite only after short trips. it also has little power under 2000rpm. Both part stores testers were down

so I couldnt get it checked. Im thinking its the voltage regulator-again. The battery is holding a charge but for how long. Help PLEASE!!!!

Manarius · #2 08-02-2006, 06:35 PM

Alternator. You described the classic signs of its failure.

dannmarr · #3 08-02-2006, 07:36 PM

Use a volt meter on the battery. check it before you start the car and after. You should have about 12v when it's off and around 14v when it's on. You can also check the battery after a trip and see if the voltage slowly drops indicating a draw somewhere. You should be able to drive about an hour on the battery alone before it dies. Good luck.

demonsvx · #4 08-02-2006, 08:21 PM

Where are all the grounds anyway. Iknow of one below the battery, on the firewall,and the exhaust near the right tailpipe. Is there any more? My local junkyard has a alternator for $50.00 so Im getting that one for a spare to rebuild. Thanks for any info. Damian

Trevor · #5 08-02-2006, 11:47 PM

Quote:

Originally Posted by demonsvx

Where are all the grounds anyway. Iknow of one below the battery, on the firewall,and the exhaust near the right tailpipe. Is there any more? My local junkyard has a alternator for $50.00 so Im getting that one for a spare to rebuild. Thanks for any info. Damian

It is difficult to understand why this is an intermittent problem, other than to assume that there is a suspect connection within the diode bridge rectifier network. There is no reason to assume that the repair should be expensive.

If you have some mechanical ability you could open up the alternator and follow your nose. That said, having the spare available from a wrecker would assist in your effort, i.e. back up or as a model to work on.

The dash indicator lights, test circuit, incorporates blocking diodes to eliminate a sneak circuit which would otherwise exist. In an event involving faults within the alternator rectifier network, alternating current is induced on line. The result is pulses of reverse voltage, dependant on engine revs., which pass the blocking diodes in the test circuit and energise the indicator lights accordingly.