How to check my alternator - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Hags86 · 09-10-2017, 05:02 AM

Hi All

I think I've got a bad alternator but looking for some help.

When the car is running I get about 11.9V measured at the battery to gnd or from the alternator output to gnd. It looks like the alternator is generating anything as I'd expect to see about 14V.

But, I don't have a charge light on the dash. I assume that this should come in if the alternator is dead.

Thoughts?

alan.chalkley · 09-10-2017, 05:34 AM

Also check those voltages with high beam lights on and engine running.

BirdTRD · 09-10-2017, 11:13 AM

Quote:

Originally Posted by Hags86

Hi All

I think I've got a bad alternator but looking for some help.

When the car is running I get about 11.9V measured at the battery to gnd or from the alternator output to gnd. It looks like the alternator is generating anything as I'd expect to see about 14V.

But, I don't have a charge light on the dash. I assume that this should come in if the alternator is dead.

Thoughts?

So just for a point of reference, 1st pic is car off battery voltage, 2nd pic is car idling nothing on and the 3rd pic is car idling, high beams on. Looks like your alternator isn't putting out the proper voltage.

09-10-2017, 05:02 AM	#1
Hags86 Senior Member Join Date: Mar 2013 Drives: Toyota GTS 86 Location: Melbourne Australia Posts: 243 Thanks: 21 Thanked 118 Times in 65 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	How to check my alternator Hi All I think I've got a bad alternator but looking for some help. When the car is running I get about 11.9V measured at the battery to gnd or from the alternator output to gnd. It looks like the alternator is generating anything as I'd expect to see about 14V. But, I don't have a charge light on the dash. I assume that this should come in if the alternator is dead. Thoughts?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Alternator Options	AtlasMick	Electronics \| Audio \| NAV \| Infotainment	19	08-18-2021 03:02 PM
My alternator dying?	stockysnail	Electronics \| Audio \| NAV \| Infotainment	26	08-17-2021 02:23 PM
Bad battery or bad alternator?	edigeek	Issues \| Warranty \| Recalls / TSB	19	03-13-2017 07:59 PM
How will I know I need an alternator upgrade?	driftking96	Electronics \| Audio \| NAV \| Infotainment	3	06-22-2016 08:47 AM
Alternator pulley??	xpicer	Scion FR-S / Toyota 86 GT86 General Forum	2	10-13-2012 08:54 AM

09-10-2017, 05:34 AM	#2
alan.chalkley Senior Member Join Date: Feb 2012 Drives: 4wd zooks Location: Sydney / Australia Posts: 495 Thanks: 135 Thanked 167 Times in 108 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	Also check those voltages with high beam lights on and engine running.

User Name		Remember Me?
Password