Sound from an Alternator

[Splat]

Hi guys, 

That's a humming noise coming from the alternator when the ignition key is turned on. WHEN THE VEHICLE IS NOT STARTED. Does anyone know about this? I called a few electrician but they too are clueless. Alternator indicator light goes off when stated and the charging is good. Everything is functioning very well.  

Like a Bermuda Triangle phenomenon  🤣 your kind input may help me figure things out. 

[PerfMad]

22 minutes ago, Splat said:

Hi guys, 

That's a humming noise coming from the alternator when the ignition key is turned on. WHEN THE VEHICLE IS NOT STARTED. Does anyone know about this? I called a few electrician but they too are clueless. Alternator indicator light goes off when stated and the charging is good. Everything is functioning very well.  

Like a Bermuda Triangle phenomenon  🤣 your kind input may help me figure things out. 

mmm usually this is highly unlikely. You can't hear such noise from alternator unless vehicle is operating. Are you sure its the alternator? My hunch is check your fuel pump. It could be the fuel pump priming abnormal sound if it wasn't there before.

[Twin Turbo]

Did you wash the engine?

 

[iRage]

Uhhh.....there really isn't anything for the alternator to hum when it is not running is there ? My guess too is that is is probably the fuel pump. Depending on the car and the EVAC system it has..it can also be the EVAC system but that usually hums or makes a similar noise AFTER the car has been running.

 

[harshansenadhir]

What's the vehicle, model. Hardly anything can cause a humming noise from alternator when only ignition is switched on. 

in order to isolate the problem, can you disconnect the 12v+ wire from the alternator and switch on the ignition to see whether the humming noise is still there or not. 

[Splat]

On 11/24/2022 at 10:19 AM, PerfMad said:

mmm usually this is highly unlikely. You can't hear such noise from alternator unless vehicle is operating. Are you sure its the alternator? My hunch is check your fuel pump. It could be the fuel pump priming abnormal sound if it wasn't there before.

Thank you @PerfMad, I shall check on this. Thank you for taking the trouble to respond. Good luck.