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i want to see if my alternator is still good. what should the voltage be when the key is on ? also what should be the voltage be of the alternator when the car is running?
 

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Should be +13 when running, usually around 13.5-14.5, key on with no accessories running, (or key off) anything over 12 should be fine. This is just my opinion.

A scan tool may show a little less voltage than a voltmeter hooked directly to the battery terminals.

A bad alternator will often draw your voltage under 12 (when running) and in fact your voltage will be less when running than not (a SURE sign of trouble). You can stick voltmeter leads on your battery terminals to check.

[This message has been edited by Zap (edited August 15, 2001).]



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Quick Tests:
1. While car is running disconnect battery, Car should still run if altenator is charging.

2. While car is running place a metal object (screw driver, wrench) on the back of the altenator on the silver looking bearing cap (about the size of a quarter). There should be a strong magnetic pull if it's charging.

Regards
KS

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87GN, 12.05 @ 111, SIXTY FOOT 1.60-LAUNCH 15#, BONE STOCK LONG BLOCK, STOCK I.C. (BELL MOUTHED), STOCK TRANS/CONV, Stock Turbo, 009'S, RED'S 107 CHIP. HOME MADE 3" DOWN PIPE. RUNS CONSISTANT 12.10'S-12.11'S.

http://www.geocities.com/kdslaby/solidworks.html
 

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Or you could have a crazy alt that charges when it wants to!Thats what my crazy azz car does.New one is on its way.My SM 11 is very correct on its readings.You should get a guage or scan tool to keep an eye on things"Im sure having mine saved me from being broke down.

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Keith Davis--Moneypit 86GN,Astroroof,DigDash'TTA crank,Ported polished heads & matched intake'TRW .30 forged pistons & PT51 Turbo,Manly SS valves,CC 206-206 cam'Postons headers,Orange stripe conv.THDP,2 1/2 exhaust'Hooker comp. mufflers'SMC alky,Boost command,Scanmaster2,MSD50 inj,Nitto DR's 275/50/15,All the braces,All gauges VDO.
12.8 @ 102 is with stock setup no times for new setup yet.


 
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