Toyota GT86 Alternator: Specs, Fitment & Common Faults

On the GT86, a genuinely useful, free diagnostic test reveals whether a whine is genuinely a bearing fault, not the alternator.

Illustration for editorial purposes

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OEM Part Number: 23700AA750

Genuinely important to know: GT86 was jointly developed with Subaru and is actually built at Subaru's Gunma plant — genuine part numbers are Subaru references, not Toyota ones. 2017-2019 facelift cars could come with either a 130A or 150A alternator from the factory, and fitting the wrong amp rating risks an underpowered electrical system. Verify your exact rating before ordering, since the two look physically similar.

2013-2016 (pre-facelift), 130 Amp	Subaru OEM: 23700AA750 (also referenced as 23700AA751, SU003-00484)
2017-2019, 130 Amp variant	Subaru OEM: SU003-05860
2017-2019, 150 Amp variant	Subaru OEM: SU003-06464

A Genuinely Useful, Free Diagnostic Test Worth Trying — Toyota GT86 Alternator

If you're hearing a whine or grinding noise that might be the alternator, this is genuinely worth trying before condemning the part: with the engine idling, listen to the noise, then progressively add electrical load — headlights, heated rear window, air conditioning. A genuine bearing fault typically gets louder as load increases. It's also worth listening for whether the noise briefly disappears then returns a second or two after decelerating from higher revs — this pattern is a fairly reliable sign of genuine bearing wear.

A genuinely useful point worth knowing if a noise persists after alternator replacement: it's genuinely worth checking the belt tensioner before assuming the replacement part is also faulty — a worn tensioner pulley can produce a very similar sound to a failing alternator bearing.

It's also worth knowing that a breakdown recovery call-out for alternator failure, particularly away from home, can come with a real premium attached.

Toyota GT86 Alternator: Often Blamed on the Battery Instead

On the Toyota GT86, dim lights, slow starts, a battery that won't hold charge — these symptoms point equally to a weak battery or a failing alternator, and that overlap is why so many replacements target the wrong part first, with the real problem only surfacing weeks later.

Before you buy: alternator output rating varies by engine size and trim, particularly on cars with more onboard electronics. Always confirm against your VIN before ordering.

Toyota GT86 Alternator: What It Does

Electricity generation while the Toyota GT86's engine is running is the alternator's job, charging the battery and directly powering the electrical systems. When it's working properly, the battery mostly just handles engine starting and short demand spikes, not day-to-day electrical load.

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Toyota GT86 Alternator: Warning Signs, DIY Difficulty & Aftermarket Advice

These are the same regardless of make or model — see our full Alternator Guide for symptoms to watch for (plus a genuinely useful two-minute test to confirm it's not the battery instead), confirming the right amperage and fitment against your VIN, and which brands are worth trusting.

More Toyota Alternator

The same part, covered across other Toyota models.