How to replace, diagnose and repair Toyota Alternator - Disassemble and Reassemble

This alternator is from a 1998 Rav4 Toyota

[@danblankenship5744]

To confirm that you have an alternator problem and not an external wiring or connection problem, do these simple checks before you grab a wrench: With a charged battery start the car. Do the following voltage checks. Measure across the positive and negative posts and remember the value. Move the negative meter lead to the engine block. Make sure that the voltage is the same. Move the positive lead to the large post on the alternator. If you have a dead alternator then this voltage will be slightly less than the battery reading (small resistance in the wire). Turn the Car OFF and remove the three-wire plug from the alternator. Start the car (the bad battery indicator should be OFF) and measure each of the three wires in the removed plug. They all should have the 12V present. If you have confirmed these points then it is safe to assume you have a bad alternator. It is easier to remove the alternator before performing the following checks to determine your failure. As soon as you have removed the outer cover it is easy to check the stator windings, the rotor windings, the brushes and the diodes with a simple meter. You don't want to remove any screws before you make these checks. that way you can find the fault before you move connections around. To check the rotor windings, the slip-ring connections, and the brushes: measure the resistance across the two screws holding the brush assembly in place. It should read less than 10 Ohms and stay there as you slowly spin the rotor. Then confirm that these screws are not shorted to the chassis ground (OL on the DMM). To check the stator windings and the diodes: Measure the resistance between the 4 screws located around the edge. They all should be around 0 Ohms. In "diode Check" mode measure any screw to chassis ground and then reverse the leads. In one direction you will read something like 0.3 volts and in the other direction, it needs to read OL (overload or infinity Ohms). Many times you will find the brushes are too warn and the first check showed OL instead of 10 Ohms. Why replace the alternator when a $30 part will work?

[@briholt100]

Do you have a vid in mind about testing the alternator while still attached? The following isn't clear to me: Turn the Car OFF and remove the three-wire plug from the alternator. Start the car (the bad battery indicator should be OFF) and measure each of the three wires in the removed plug. They all should have the 12V present. ---how do you test these 3? Do you keep the neg meter reader on the engine block?

[@nakayria164]

Tuning in from Jamaica 🇯🇲. Awesome video. Very accurate and detailed. Good job 👌

[@gabrielguadarrama8701]

Amazing to find people that still do this kind of work

[@tgmac8288]

Still have a lot of handy people around you :)

[@Harry96171]

Very helpful and well explained, thank you.

[@robertmacfry5629]

thanks i fixed mine with this , video cheers mate

[@David-yh5po]

Thanks for sharing this video with us.

[@smailbouadi5000]

Thank you so much bro that’s exactly what I need for my test tomorrow

[@tgmac8288]

:)

[@hulkhogan4383]

Awesome video of instruction on rebuild. Rate #1 in my view.

[@tgmac8288]

:)

[@lxmoomum]

Thank you for your helpful video

[@r0ckworthy]

The music is perfect!

[@tgmac8288]

:)

[@myanmar8044]

Thank Godbless you save a lot of money 💰

[@stclairstclair]

When I was a young GM mechanic my alternator went out so I went to the parts counter and get a diode bridge and regulator and proceeded to rebuild my alternator, When I was all done the parts manager walked in and said "hey dumbass I could have sold you a new alternator for less then you just paid for parts" I was not pleased, And I do believe it was the last alternator I remember cracking open.

[@tgmac8288]

😄Might as well pick one up from Junk Yard for cheaper price. 😃:)kzbin.infogaming/emoji/7ff574f2/emoji_u1f604.png

[@RTC_SA]

thanks the info was very helpful for me

[@tgmac8288]

Thanks for your feedback!

[@mountainhopper9573]

Over 30 Years ago a chev voltage went up to 18v. So t bought a regulator And took it apart like you did and replaced the regulator problem fixed. Voltage back to 14v.

[@tgmac8288]

Well done! :}

[@Schaefft]

Is there an ohm number that the rectifier should ideally have for all diodes? I checked mine and it seems to be 380 ohm for all but one where there doesnt seem to be any connectivity (which would confirm my suspicion of a faulty rectifier causing the alternator to not charge the battery anymore). Thanks for the video!

[@JSadeiu]

I'm going to try this. My alternator stopped working after I power washed the engine bay (oops). I like the music

[@tgmac8288]

Glad you like the music. Please update your result.

[@JSadeiu]

@@tgmac8288 My rotor did not have continuity between slip rings and had a ground short. Plus, my rectifier didn't pass continuity in either direction. Time to buy a new one. Thanks for your help.

[@bwest-yq3uc]

If you would show what the limits or specs are on the testing it would be very helpful and informative to the viewer. tks.

[@gulabkhan5360]

Good morning

[@paulgore1216]

It would have been helpful if I could see where you were placing your probes for measuring continuity and resistance.

[@tommasodanea5780]

Hi and congratulations for the video first, I have a problem I have an error code P2501 high voltage terminal L + of the alternator lamp what can it be, the alternator charges well, thanks I am waiting for an answer

[@electricsuncafe]

Im following this guide (very grateful by the way) and I’m getting no resistance (1) across the slip rings - where does this mean the fault is, and can it be fixed? I cleaned them up and make sure contact was good

[@tgmac8288]

There is a short inside the rotor. Would suggest to replace the alternator replaced - new or used.

[@electricsuncafe]

@@tgmac8288 just to be clear by no resistance I don’t mean an open circuit connection I mean no connection at all

[@tgmac8288]

​@@electricsuncafe"Zero" ohm = shorted circuit. Open = high resistance or broken coil wire. Both mean rotor coil circuit problem and the replacement of the alternator is needed. Not a easy fix. Get a used alternator from auto wrecker will be the cheapest way.

[@tgmac8288]

No connection = open circuit connection = infinite high resistance. No resistance = zero ohm = shorted circuit

[@nutchanonbhujomjit570]

In this video. Why not check Rectifier/Diodes first?

[@tgmac8288]

Of course, one can start checking Rectifier/Diodes first. However, one supposes to check out all parts if possible for a permanent fix. It is totally personal preference where to start. The method I was using that was "outside in" in order to cover all parts. What do you think?

[@ahmadkamali8547]

But yu didn't chk the countinety between sliprings brushes n the ground also the diodes with ground

[@rameshjaimani1465]

what happen to the regulator. How did you change it.

[@tgmac8288]

If you disassemble the alternator as shown in video, you should be able to change the regulator easily. Before you do that, maybe you should check out the price of a new alternator which could be cheaper than a regulator. Might as well to get the whole unit.

[@ronnieperalta4051]

How do you check the regulator? You did not test it??

[@tgmac8288]

Did you have an alternator problem and watched this whole video? This video is to show you how to repair Toyota alternator problem. If you did watch the video, at 7:01 narrow out all other possibilities to conclude that the regulator were bad and needed to be replaced.

[@abousamah1967]

Sir why stator 4 terminsls instead 3 terminals

[@tgmac8288]

Why 3 not 4?

[@mridware9694]

How you fix the voltage issue

[@tgmac8288]

Did you perform as this video shown?

[@mridware9694]

@@tgmac8288 yess

[@tgmac8288]

Can you be more descriptive about the problem?

[@mridware9694]

@@tgmac8288 i have 14.2 volts at cold start and 13.2 at hot start and when i apply full load the voltage drops to 12.6 and rpm also drops to 500 but after 40 seconds rpm return to 850 and voltage remain same and if i rev the engine to 2000 rpm then voltage comes to 13 volts

[@tgmac8288]

Sounds like you have a voltage regular problem. Are you from USA or where?

[@niskristensen7006]

The video would be far better without bagground music

[@tgmac8288]

Once it is downloaded to uTube, music cannot be removed separately. I had compliments about this music and thanks to your comment.

[@RagedContinuum]

this is based bg music whats ur problem