alternator
Freshman User
Joined: Feb 2007
Posts: 38
Likes: 0
You can use a voltmeter and see how much juice its pushing, but that doesnt tell you anything about how the brushes and internals are. You can however take the alternator to a parts store for a full checkup. BUt be ware, if the thing is about to go, the test will finish it off!! I have changed two in the parking lot because of this.
Posting Guru
Joined: Sep 2004
Posts: 1,915
Likes: 1
From: Yokosuka, Honshu, Japan
Read the voltage across your battery terminals with a voltmeter with the engine running. I believe it should be putting out around 13-15 volts, which it still may be close, but not enough amperage -- I can't remember if the idiot light senses one or both of those values.
Post Fiend
Joined: Jun 2002
Posts: 13,873
Likes: 3
From: Atlanta GA
imo, The only reason the tester finishes off an marginal alt is because it was not done correctly. I have probably tested literally a thousand alternators and/or charging systems and never croaked an alt. that was putting out current.
> is there a SIMPLE way to check the alternator to see if its bad????
Make sure the battery is fully charged. Start the vehicle, put on the high beam headlamps and heater system, put it at an 1800 rpm idle. Using remote test leads (so you are not directly under the hood) see if you are getting at least 13.6 if not over 14 volts.
Then shut it off, remove the neg battery cable and put the DMM on it and see if you have a short. If so, remove the alt connector and try again.
> is there a SIMPLE way to check the alternator to see if its bad????
Make sure the battery is fully charged. Start the vehicle, put on the high beam headlamps and heater system, put it at an 1800 rpm idle. Using remote test leads (so you are not directly under the hood) see if you are getting at least 13.6 if not over 14 volts.
Then shut it off, remove the neg battery cable and put the DMM on it and see if you have a short. If so, remove the alt connector and try again.
Junior User
Joined: May 2004
Posts: 66
Likes: 0
From: Idaho Panhandle
Alternator:
Back in the old days we used to touch a screwdriver to the rear of the alternator at the center shaft point with the vehicle running and if it was magnetic it was still good. Make sure your screwdriver isnt magnetic before you start.
Bob
Bob
Post Fiend
Joined: Jun 2002
Posts: 13,873
Likes: 3
From: Atlanta GA
> Back in the old days we used to touch a screwdriver to the rear of the alternator
I - think back in the old days they used generators, not alternators. I think they (mostly Chevy) stopped using generators in the 60s.
I - think back in the old days they used generators, not alternators. I think they (mostly Chevy) stopped using generators in the 60s.
Last edited by rebocardo; May 19, 2007 at 10:23 AM.
