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

i.imgur.com/gk0Q8BT.jpg


Seems like battery current sensor talks to ecm, ecm controls generator field. Is it installed between battery post and generator + cable like in the picture. All the current should be passing though that device.

See the hash marks around the screen edges? Each square is a DIV or division.

Horizontally each hash mark, or division is 50 msec. There's 10 hash marks, so it's a 500 msec time frame across.

It's an 8v square wave, peak to valley.

Hold it at 1500 rpms and check for voltage drop between battery positive and alternator post. Then check alternator housing and battery negative.

I wish I knew what those acronyms were: THB, EIB, IB, VCIB,...

With the car running, read each voltage coming out of the battery current sensor and make it go the opposite with a test light. If you read voltage there, pull it down, through a test light connected to ground. If you see low volts, pull it up, through a test light connected to battery positive. I would go one at a time on each wire and listen for any changes.

Minor wrote: I see there a link in blue on Generator is that to the rest of the information about these waves and troubleshooting?

I was searching for "generator" in the document, that's why lol.

Minor wrote: I saw a wire way down in front of the wheel that looked like a ground and the bolt was really rusted. I'm now wondering if it could be a ground wire in this circuit.

By all means, you don't need my permission to check suspicious grounds.

I don't know how autozone tests alternators.

I don't have a scope to view waveforms but here's how I'd check. Take a regular old voltmeter and measure the voltage on that RLO wire, which I believe is the field control wire. When you're revving the engine up and down that voltage should fluctuate. That should be enough to tell you if the ECM has control or not.

The waveforms were showing 0v - 8v square waves so on your meter you should see around 4V average and should move around.

Or touch a test light, connected to battery positive or negative and see if it flashes or not. If it's pulsing, then try to give the alternator a gentle hit - maybe bad brush contact on rotor?

If it's not pulsing, then I'd check the RLO wire at the computer harness.

If nothing there, then I'd focus again on that battery current sensor.

Just curious, what happens if you leave that battery current sensor disconnected?

The M wire is also worth checking out at the computer. I'm guessing there's voltage on there that goes to the ECM. I worries about an open on that wire.

Find a parts store that has a advanced battery tester that can check alternator, diodes and such when cranking as I haven't had a alternator tested with a bench test machine in years. Not knocking them because I don't know how advanced those are compared to a couple thousand dollar battery / alternator tester.

IF you turn the heater, lights, etc on what kind of readings to you get and does the light stay on or have you not tried that yet.

Loved the days when a alternator was just a alternator but not anymore with all the tech out there. Almost need a engineering degree to diagnose these anymore, well maybe not quite but getting close it seems.

Following along for educational purposes. I've never dug into Toyota systems with battery current sensors before.

For whatever it's worth, I'm not entirely sure that this is a true PCM controlled alternator? :silly: From what jreardon posted, RLO behaves a lot like the FR signal of older Toyota alternators. It's not a command from the PCM to the alternator, but a feedback signal from the alternator to the PCM about alternator load. If it's truly a feedback circuit, then it has no impact on charging rate.

The ALT/M circuit is new to me. The voltage specification chart wants B+, more or less, and doesn't specify any kind of pulse width control. This could be a high/low charge rate command circuit? Just speculating. :silly: Doesn't seem like a true 'command' circuit like we see on other smart charging systems.

My experience with bench testing newer alternators is... It doesn't mean anything.

After hours of reading on alternator testers and how they hook up to terminals with RLO and trying to figure out wtf RLO stands for, one manual had it defined as Regulated Load Output. Finally! I googled that in quotes and there's an article about it on THIS VERY CAR. Read the last sentence lol.

cdn.ymaws.com/apra.org/resource/resmgr/G...ine/Jan-Feb_2016.pdf

Here's your fix (?):

Any one read Russian? The waveform of RLO and M is pictured there. I don't know if it's known good or known bad. I still don't understand with Google translate on

mlab.org.ua/forum/viewtopic.php?f=10&t=4704

www.testmyalternator.com/en/news/technic...s-tma-technical.html



pmmonline.co.uk/technical/regulator-terminals-what-they-mean/

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

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?

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.