2008 Toyota Rav4 2x4 2.4 not charging alternator and battery good

www.mr2oc.com/188-v6-mr2-forum/606337-alternator-questions.html

Thanks, I need that I did use the meter and I did see 2 volts DC. If I connect the scope to the ROL to battery ground I see a wave with a wide pattern. So after reading this, I am thinking if I disconnect the RLO wire and the Alternator is good I should see it charge like normal. If it does charge then I have to assume I have a bad Alternator even though it was said to be good on the bench test at auto zone. Would you not agree.

I figure out someone been here before on this car they mark the RLO with a blue marker on the connector. So I bet they removed that wire out of the connector to see if it went to charge and they want to make sure they put it back in the right place. I like to know why this is not in any manuals? How are you supposed to troubleshoot something if you don't understand how the system works?

Another thing that across my mind is that use old-style bench test they would just not send that signal to see if the output of the Alternator was working, if it went into the standard charge mode they may be calling it good to get out of buying a better test machine. So I may very well have a bad regulator inside the Alternator which was what I have suspected all along.

Yes, but that damn battery current sensor is an input to the ECM, and the ECM sends the signal to the regulator. So it's not outside the realm of possibility that bad inputs are causing bad output. You said you ohm tested, but Paul said "if it ohms good it could still be bad, if it oms out bad, it's bad." However if you saw the RLO signal changing when you turned on all the accessories, that would mean the battery current sensor is sending variable inputs (correct, i hope) and I would lean towards bad alternator. Maybe, uggh, I'd hate to be wrong on this.

But I doesn't hurt to ask and see what equipment Autozone is using to test the alternator. Google up the test equipment manual lol, and see for yourself if it can test an alternator fully.

Is the serpentine belt tight and can you see the inside of alternator whirling away with a flashlight? Did you see the waveform on that russian language forum? Did you scope the M wire too?

Here one thing that not making sense to me, why don't I see any codes in the ECM? It had to running until the battery was almost 9 volt before it set anything. Then the code is P1602 interior malfunction. Really low battery of back up power supply. .I notice also the Alternator sounds funny like some lose inside. What pulls that gear or clutch in iside it. It is turning I don't no if it's up to speed it's hard to see it. I did find this to troubleshoot with for those that might ha ve to do this themselves I place a PDF of it in here

Minor wrote: I notice also the Alternator sounds funny like some lose inside.

I think that alternator is smoked. :lol: Time for a new one, IMO. OE or Denso. Don't play games with parts store garbage, it's not worth your time.

What pulls that gear or clutch in iside it.

The clutch pulley is either a OAP or an OAD design:

www.daycoproducts.com/dayco%C2%AE-overru...ecoupler-pulleys-oad

Either way, if the pulley spins but the rotor inside the alternator doesn't, the clutch is toast. Unlikely, since the bench tester reported OK, but still possible. You can also have OAP/OADs that make abnormal noise, but are still solidly locked to the alternator.

OAD/OAP replacement is possible, but requires a special tool set.

Minor wrote: It had to running until the battery was almost 9 volt before it set anything. Then the code is P1602 interior malfunction. Really low battery of back up power supply.

More like 0V according to DTC lol.


I'd like to know circuit design of the battery current sensor, just curious... It's probably fine since it's not setting any codes, but try and set a code to test it lol

If (IF IF IF) the alternator is bad, what smoked it? Have you asked the owner if he changed the battery. Maybe that alternator was working overtime trying to charge dead batteries all the time and that's what killed it.

You said you ohm tested, but Paul said "if it ohms good it could still be bad, if it oms out bad, it's bad."

I would like to revise my statement. When Paul said that I think he was talking about injectors and ignition coils, stuff that carries more amps than that stupid battery current sensor.

That green power on the IG terminal is fed by 10A fuse. Capture current ramp of that and compare to known good, if you do change out the alternator. Or if you have no current flow on there maybe that suggests dead regulator.

Last night while I was going through check voltages and waveforms something trigger the alternator to kick in. When it did it did put out 13.89 but it only lasted for about 20 seconds. I did notice when it did all the noise went away when the clutch lock-in. It appears no matter what I have to replace it because the clutch system is not working correctly. So I figure to start there after realizing the Clutch system in the alternator itself is bad. Then see what happens with a known good one. (Well I Hope wouldn't be the first time I got a bad one).

Sorry guys didn't get this taken in till late tonight but this time when it was on the bench test it did fail on the second test. The clutch didn't engage when it failed. So It's looking like I might be on the right track...We'll find out tomorrow when I get in back on the truck.

Last night while I was going through check voltages and waveforms some trigger the alternator to kick in. When it did it did put out 13.89 but it only lasted for about 20 seconds. I did notice when it did all the noise went away when the clutch lock-in. I t appears no matter what I have to replace it because the clutch system is not working correctly. So I figure to start there after realizing the Clutch system in the alternator itself is bad. Then see what happens with a known good one. (Well I Hope wouldn't be the first time I got a bad one).

OK, new Alternator installed problem fixed. Here my conclusion on it. First thing you should know is this truck had no charging codes in it but the Light was on. When I tried using the scope I could only get one waveform that didn't match any of them and it was a lot wider, about double of the largest one shown. The other thing I notice was even when the engine RPM changed the waveform didn't change any. All my wires check out, no short to grounds and had continuity. All the voltages going to the 4 pin connector were OK. Just the waveform on the RLO wire never changed.

Now how I came to the point of replacing the Alternator even after it tested OK. After thinking about how the inside of the alternator was built the only thing I could come up with was that maybe the armature was spinning but not at the correct speed but fast enough to keep it from throwing a code but not enough to charge the system. It just so happen I have the scope hooked up on the gray wire on the 4 pin connector and I was using my voltmeter check voltages across the battery post and from the alternator to the battery looking for anything that didn't look right. Thinking maybe I missed a bad wire or ground somehow. Something happening while I was doing it that engaged the clutch inside the alternator which was what I had been trying to make happen for 3 days and could figure out how to make it happen. Yesterday I noticed that the Alternator had started making more noise than it was. I first thought it was the AC Clutch till I got right on top of it checking the 4 pin connectors and after reading it had some kind of clutch setup inside I realize it was the Alternator make it. When the clutch engaged it made a funny sound and all the noise stopped. I grab my meter and check the voltage across the battery and it was charging 13.89. Witch told me why it tested good on the bench and that the test machine may have higher voltage or strong waveform and triggering the internal regulator so the clutch would engage. The reason I couldn't get it to engage I feel is because of the lower battery voltage caused by it not charging was not Strong enough to pull it in, most of the time or fully engage it. It just so happens that I had charged the battery before I started testing and that's why it engaged on the car finally.

So final notes to take to the ball game when checking these computer controlled system out.
1. make sure you have a fully charged battery before testing or some things may not function as they should.
2. If you see a waveform but its pattern is larger and doesn't seem to change with engine RPM, start suspecting the clutch system is not engaging correctly and it may not throw codes because is may still spin fast enough to stop it from sitting the codes. Note: you may not be able to engage the cutch in the Alternator with the battery being fully charged due to amperage differences and lack of pulling power. Even then if it is completely out it may not engage.
3. Do your homework the more you know about the system the better and faster you'll be able to find the problem
4. Don't count on a bench test to diagnosis these systems. The voltage on test machines could be different and just enough to pull in a defective part and make it work because of higher amperages.

Last thing.
This truck came in with a none charging battery, light on and no codes point at any problems, on anything in the truck. Clean of codes.