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alternator testing


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engine not running battery voltage as low as 9v (much lower engine may not start).

as cranking engine voltage would drop by how much depends on the size of your battery and power of your starter motor.

with engine running initially voltage will return to pre starting voltage then rise to between 13.8-14.2 volts alternator has died or there is a strange external load on battery if you do not see the voltage rise.

check quality of earth on engine and alternator, quality of live to alternator.

with one terminal of multimeter on alternator casing and other on battery neg the volt meter should read 0v.

with one terminal of multimeter on alternator live and other on battery poss the volt meter should read 0v.

if the readings are above 0 then there is a fault with that line.

with engine not running and ing on the ign light should be on in cab and should go off when the engine is running.

If the ign light is not on with ign on then take ign wire off back of the alt and touch it against a good neg source the light should come on if not check bulb first then wiring.

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with one terminal of multimeter on alternator casing and other on battery neg the volt meter should read 0v.

with one terminal of multimeter on alternator live and other on battery poss the volt meter should read 0v.

if the readings are above 0 then there is a fault with that line.

Is this with engine running? Ta.

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hi to all

just tested battery/alternator with multimeter getting a reading of 14.27 across the battery terminals.is this good or is it to high.also tested alternator direct with multimeter getting a reading of about 14.27 and 14.30 is this good or is it to high.these readings are with engine running at tick over when engine is warm

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