Alternator Testing
Thread Starter
Le Mans Master
Joined: Aug 2003
Posts: 9,884
Likes: 3
From: Magnolia Mississippi
St. Jude '03-'04-'05-'06-'07
Alternator Testing
Posted earlier: Where have the Volts Gone? - just watched as the voltage display went lower and lower, then would not start... well... replaced battery and she starts fine, but showing voltage at 11.1 - 11.4 (with all assy running - AC/radio/lights/interior light) all on... but wanted to check the alt voltage output... "Does anyone know how to test the alt output voltage?" - something a simpleton could do... namely myself... have VOM.... thanks
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: Alternator Testing (daddvi)
The voltmeter on your dash has already tested it for you and the answer is (not 42) your alternator is not putting out any current that amounts to a hill of beans. There is a chance that the fusible link in the alternator output wire is blown and with the engine running your voltmeter should read 14.3 volts on the large wire on the bolt on the end of the alternator. There should be less than 0.5 volts between the positive battery terminal and the alternator output with the engine running. Your red battery symbol on the dash should also be on which tells you that the alternator is not working. You can also remove the neg battery cable and measure the resistance between the battery positive terminal and the alternator output. The resistance should be the same as touching the meter probes together.
Thread Starter
Le Mans Master
Joined: Aug 2003
Posts: 9,884
Likes: 3
From: Magnolia Mississippi
St. Jude '03-'04-'05-'06-'07
Re: Alternator Testing (jfb)
thanks jfb: well, did the testing and BINGO - no alt output at all... well though maybe just do the novice thing and wiggle the wires at the alt... surprise to me, the main (RED) just came off the connector.... broken... replace connector and now dash volts read 13.3 under full load... sometimes the small things just get away from you... thanks... vinnie
