Eric, go to my profile page and download the 2011 wiring diagrams:

http://www.rav4world.com/forums/members/32793-junebug.html

Since you have the Limited with the auto climate control, the blower is controlled by an ECM called the A/C amplifier, instead of a simple rotary switch with resistors.

You might want to run this diagnostic procedure and see if any error codes show up:


CHECK MODE PROCEDURE
1. PANEL DIAGNOSIS (INDICATOR CHECK)
(a) Turn the ignition switch to LOCK.
(b) Turn the ignition switch ON while simultaneously
pressing the A/C control AUTO switch and the REC/
FRS switch.
(c) Check that all indicators and the display area are
turned on and off 4 times in succession at 1 second
intervals.

HINT:
After the indicator check is completed, the system
automatically enters sensor check mode.
(d) Press the OFF switch to terminate the panel
diagnosis.
2. PANEL DIAGNOSIS (SENSOR CHECK)
(a) Perform the indicator check.
HINT:
After the indicator check is completed, the system
automatically enters sensor check mode.
(b) Press the REC/FRS switch to enter actuator check
mode.
(c) After the actuator check is completed, press the
AUTO switch to enter sensor check mode.
NOTICE:
The sensor check must be performed again after
the actuator check is completed because sensor
check mode, which starts automatically after the
indicator check, cannot fully detect
malfunctions.
(d) Check the sensor check results displayed on the set
temperature display.

HINT:
• The illustration shows the display when code 21
is output.
• When 2 or more sensor check codes are
detected, the codes are displayed in ascending
numerical order.
• In cases with 2 or more codes, if they are difficult
to read, press the DEF switch to activate the step
operation and display them one by one.
• The codes are displayed in ascending numerical
order as the DEF switch is pressed.
(e) When any sensor check codes are displayed, refer
to the DTC chart (see page AC-39).
(f) Press the OFF switch to terminate the panel
diagnosis.
HINT:
Pressing the REC/FRS switch returns the system to
actuator check mode.

3. PANEL DIAGNOSIS (CLEAR SENSOR CHECK CODE)
(a) Inspect, and repair or replace the malfunctioning
parts.
(b) Clear the sensor check codes.

(1) While pressing the DEF switch during sensor
check mode, press the Rr DEF switch.
HINT:
Sensor check codes can be cleared by removing
the ECU-B2 fuse from the engine room No. 2
relay block for more than 60 seconds.
(c) Perform the sensor check and confirm that normal
code 00 is displayed.

4. PANEL DIAGNOSIS (ACTUATOR CHECK)
(a) Start the engine and warm it up.
(b) Perform the indicator check.
(c) When the sensor check is started after the indicator
check, press the REC/FRS switch to start the
actuator check.
HINT:
Perform the actuator check with the engine running.
(d) Check the temperature and blower levels by hand at
each step while the actuator check proceeds from
step 0 to 9 at 1 second intervals (continuous
operation).

HINT:
Each step number is displayed on the set
temperature display.
(e) To display step numbers one by one manually,
press the DEF switch to activate the step operation.
The step number changes each time the DEF
switch is pressed.
HINT:
• Each step number blinks at 1 second intervals
during the step operation.
• The illustration shows the display when step
number 5 is displayed.
(f) Press the OFF switch to terminate the panel
diagnosis.
HINT:
Pressing the AUTO switch returns to sensor check
mode. __________________

 

James,

Performed the diagnosis steps and Sensor check didn't come up with any codes except the normal "00".

The last step (Actuator check with car running) I might have been doing wrong...I wasn't able to adjust the blower or temp levels by hand? I could step thru the 0-9 actuators though...

Thank you for the wiring diagram but I'm still not sure which wires to check for voltage. At connector E53 (on page 5 of 9) for the blower there are three wires:

1- GND (W-B)
2- SI (Red)
3- +B (Blue)

Obviously the GND is negative...would the Blue be the positive? SI being some other signal input? The red wire is too small a gauge to carry power?

Thanks again.

Eric

 

James,

Performed the diagnosis steps and Sensor check didn't come up with any codes except the normal "00".

The last step (Actuator check with car running) I might have been doing wrong...I wasn't able to adjust the blower or temp levels by hand? I could step thru the 0-9 actuators though...

Thank you for the wiring diagram but I'm still not sure which wires to check for voltage. At connector E53 (on page 5 of 9) for the blower there are three wires:

1- GND (W-B)
2- SI (Red)
3- +B (Blue)

Obviously the GND is negative...would the Blue be the positive? SI being some other signal input? The red wire is too small a gauge to carry power?

Right you are, Eric, Blue is positive. The red wire, SI, is a signal wire from the A/C amplifier that tells the blower what speed to run. Measure between +B and GND and you should see a constant 12 volts. Between SI and GND you should see a varying voltage as you adjust the fan speed manually. It may not even be DC on that SI wire, so if you don't read anything, change to AC on your meter. There's got to be some kind of module in the blower to regulate speed since there is no resistor pack as used in the manual system.

 

James,

I do have a constant voltage from the ac amplifier, even when it is off. (it's around 13.3 dc). Couldn't make sense of the signal wire on ac or dc volts. It might be too small for my cheap meter to pick up but it does change (spike for a second) when the speed is adjusted.

There are some components inside the blower that involves a couple capacitors, an inductor, a resistor and some kind of 5 leg bridge or regulator that is mounted to a heat sink. Took a picture of it and can attach if that would help.

The bare motor will turn for a second when I apply 12 volts from a pc power supply but probably draws too much current because the power supply shuts itself down.

So...something in the electronics that is messed up and need to just buy a new blower assembly or do you have any other things I can try?

What do you think of this one if I need a new unit (sorry about the long link)

Replacement Blower Motor Assembly 06-10 2006-2010 Toyota RAV4 Limited 8710342101 | eBay

Thanks again,
Eric

 

I do have a constant voltage from the ac amplifier, even when it is off. (it's around 13.3 dc). Couldn't make sense of the signal wire on ac or dc volts. It might be too small for my cheap meter to pick up but it does change (spike for a second) when the speed is adjusted.

Eric; You can download the repair manual for the AC system at the same location you found the electrical diagrams. The manuals contain a trouble shooting chart, and you seem very capable of following it.

One other simple test is to measure that the ground wire on the blower connector really does have a good connection to chassis ground.

The signal from the AC amplifier is a pulsating DC voltage, with a varying duty cycle. This can only really be observed with an oscilloscope, but an old analog voltmeter should at least let you see the voltage change as the duty cycle changes. A digital voltmeter is almost useless for this type of reading.

Do you see the speed ramping up on the LCD display when you try to adjust it?.

 

Rick,

I'll look for and follow the troubleshooting chart as well as verify the ground.

The LCD for the fan does ramp up when I call for ac or heat...just no blower. I can hear the ac come on (compressor?) and if I have the windows open, and vent is not on recirculate, I can feel the cold air!

Eric

 

Ok James/Rick, thanks for sticking with me...I think we're getting close.

Any chance it's the AC amplifier? I'd like to make sure it's the blower controller before buying a blower assembly.

I connected voltage from my pc power supply directly to the motor (by-passing the controller). I used the 5V instead of the 12V since it had a higher amperage rating (15A vs 4A). That blower motor is good. Spins like a top.

Am going to jump connect the motor directly to connector E-53 and make sure we're good there. I did measure 13.3 vdc so no reason that shouldn't spin the blower motor too.

Guess I should perform the E-37 amplifier connector testing (procedures AC-96 and AC-97)? Haven't located the amplifier yet- is E-37 easy to reach? Only thing for the final diagnostic I can't check the wave form...

Or am I over analyzing, just buy a blower assembly from the junkyard?

Eric

 

Any chance it's the AC amplifier? I'd like to make sure it's the blower controller before buying a blower assembly.

Logical trouble shooting, I love it.

My theory is that the electronics inside the blower assembly act like a simple Triac controlled lamp dimmer, or speed controller. By varying the voltage on the gate (or more specifically the time that the gate is opened) we control the voltage getting to the device.

In this case it looks like the varying gate voltage is the SI signal from the amplifier, and the power for the motor comes on the B+ lead. Which may just stand for battery, or many older engineers still make reference to the B+ plate voltage used on vacuum tubes.

So you know that you have full battery voltage on the B+ line (Pin #3), and I assume you checked for a good ground on Pin #1, so you only need to see if the duty cycle of the 1v square wave on the SI line (pin #2) changes as you adjust the fan speed.

If you have a scope, then that's the way to go. Otherwise try using an old analog voltmeter ( with a mechanical meter and pointer) on the DC scale. Analog meters have the magic ability of displaying the "average" value of a varying DC voltage. When the duty cycle is near 1% on- 99% off, the meter will read near zero. at a 50-50 duty cycle the meter should read ~.5 volts, and at a 99-1 duty cycle it should read ~1v. Be aware though that depending on the meter, it may be difficult seeing a voltage this low.

Am going to jump connect the motor directly to connector E-53 and make sure we're good there. I did measure 13.3 vdc so no reason that shouldn't spin the blower motor too.

I assume you want to do this test to determine if the B+ pin on E-53 can deliver the proper current. As long as you're using jumper leads from the motor to the B+ lead, and not plugging E-53 onto the assembly it should be OK. I think if you were to short out the internal circuitry with E-53 connected then you could risk damaging the amplifier via the SI lead (Pin #2).

Or am I over analyzing, just buy a blower assembly from the junkyard?

You don't seem to be having any problem following the diagnostic procedures, so why not continue and make sure you are replacing the proper item.

EDIT: The location of the AC amplifier is shown on page AC-7 of the manual.

 

Rick,

I don't have a scope or analog meter. Ill try to borrow one. Or could I use a logic probe? I have one of those but never used it. There's always a first time.

On jumping the voltage on E-53- yes on not plugging it in also...don't want to make things worse.

 

I don't have a scope or analog meter. Ill try to borrow one. Or could I use a logic probe? I have one of those but never used it. There's always a first time.

The logic probe is designed to light when there is a logical "1" and be dark when there is a logical "0". In the world of logic, everything is based on 5 volts. A logical "0" is any voltage less than 2.5 volts, and a logical "1" is any voltage above 2.5 volts. Since the RAV4 amplifier is swinging from 0 to 1 volts, the logic probe will always show a "0".

Even if the voltage was a 0-5 volt signal, it is changing two full cycles per second. You could probably see that rate on a logic probe, but not if it was much faster.

It may be hard to locate an analog meter anymore. I have seen cheap ones sold at the automotive store, but they only had a 12v and 100v DC scale. I don't think you could see the voltage changing from the amplifier unless your meter had a 1v scale.

Since you have already pulled the blower assembly out, maybe you can find a friend who will let you plug it into his RAV4.

 

I haven't been following this thread but it seems like it's about to conclude.

I agree with Rick swapping it into another RAV4 Limited would be the best test at this point. Or get one from a yard but I doubt you'll save much over the eBay price. Problem is you probably can't return either.

You're probably not going the get anywhere with a the logic probe and take a chance of blowing the control module.

An analog meter would give a good indication on the pulse width modulated drive signal but although you could see it rise with the bars on the display you still wouldn't know if the readings are correct.

BTW, I had a favorite old Radio Shack analog multimeter that had seen a little too much wear & abuse over probably 30 years so I had to toss it. But before I did, I bought two more of the same model from eBay sellers. I'm a happy tester again!

 

Appreciate the added input to this thread. I measured continuity of the negative supply to body ground and there was no resistance to speak of. I jumped E-53 when unplugged directly to the blower motor and it runs full speed ahead.

I could not locate the ac amplifier to disconnect E-37 and perform those tests. In the diagram it looks like its on the driver side between the center console and the steering wheel. Not a lot of visibility there. Is it high up or do I need to remove something to get at it?

I'm leaning toward a busted blower control module (at least I hope so).

I have a buddy with a RAV4 but its not a Limited so no luck there. Maybe test drive a new RAV4 Limited and hook up my blower while I have it out for a spin. j/k

Eric

 

Rick,

Here's a picture of the topside with the 2 capacitors, 1 resistor, inductor and diode.

Unfortunately the 5 leg component is folded underneath and I buttoned everything up to do the last bit of in car testing. The part number is hard to get at without straightening the legs out and I didn't want to bust it off.

I will open it back up at my next opportunity, probably Thursday night. I like the way you were thinking about the erratic readings from the amplifier on the SI wire pointing to it not being the root cause.

Eric

 

I will open it back up at my next opportunity, probably Thursday night. I like the way you were thinking about the erratic readings from the amplifier on the SI wire pointing to it not being the root cause.Eric

Well I wouldn't worry about taking it apart again if it's a lot of work because the chances are slim that any visible part numbers are anything more than a Toyota part number and not a standard electronic component number. I guess you can at least test the diode,inductor, and make sure the caps aren't shorted.

If you can't prove the SI voltage is pulsating, then it looks like replacing the blower assembly would be the easiest step, but since the amplifier circuit is much more complicated, it is more likely to have failed. Tough decision. The fact that you saw pulses on the SI signal is a little reassuring though.

You really need to determine if the SI voltage coming out of the amplifier is changing. Since you don't have a scope or analog meter (with a low volts scale), you could try a low voltage light bulb. If I think of anything else I will post a message.

Good luck, and please let us know what you find out.

 

Wish I had time to check my Limited for you but I expect the signal on the speed control wire goes to very near 100% duty cycle at max blower speed. Might be able to read it as either 5V or 12V with a digital meter.

 

I should have time to look at it and hopefully make some more progress tomorrow (Thursday). Will try the bulb trick or borrow an analog meter...

Fred- I thought 1V was max on the SI wire and the B+ wire brings the 12V.

Anyone have any input to this question - I could not locate the ac amplifier to disconnect E-37 and perform those tests. In the diagram it looks like its on the driver side between the center console and the steering wheel. Not a lot of visibility there. Is it high up or do I need to remove something to get at it?

According to the decision tree- if I can unplug E-37 and check for 5V on the SI wire it will rule out the blower control module as the bad guy.

Thanks,

Eric

 

According to the service manual, the a/c amplifier is mounted in the area above the accelerator pedal.

 

Eric,
I haven't reviewed the schematics. That's just how I'd have designed it since 5V & 12V are the most common levels in logic and automotive applications.

I'd try the analog meter. Not sure the bulb is a "bright" idea. Altho it will integrate a pulsed signal I'd be afraid it's load on a control signal might fry something.
Fred

 

A friend has a Fluke 83V meter that looking in the operating manual can measure frequency and duty cycle. I'll get a chance to borrow it on Saturday.

Further looking in some of the exploded diagrams of the section AC-188 shows that AC Amplifier is accessible after removal of the dashboard brace and a couple air ducts. Anyone ever worked on this? Is it really buried in there that deep?

 

A friend has a Fluke 83V meter that looking in the operating manual can measure frequency and duty cycle. I'll get a chance to borrow it on Saturday.

I had a look at the Fluke manual and it sounds like this meter will be able to let you know if the AC amplifier is putting out the correct waveform. This certainly isn't your Father's multimeter. If you are interested you can download the manual here, and prepare yourself for Saturday.

Further looking in some of the exploded diagrams of the section AC-188 shows that AC Amplifier is accessible after removal of the dashboard brace and a couple air ducts. Anyone ever worked on this? Is it really buried in there that deep?

I just found those diagrams last night as well. It looks like 13 steps before you get to the AC Amplifier. Some of those steps involve removing the refrigerant, disconnecting the water lines, and removing the steering column and upper instrument panel. This is probably beyond my capabilities both mechanically and financially.

Hopefully the Fluke meter will tell you that you don't need to remove the amplifier.

 

Getting a little too complex here. Measuring frequency & duty cycle is interesting but how useful would it be in actually solving the problem? :shrug:

To me the drive signal is either there or it isn't. If not, it's the AC amp. Is, and it's the 5 pin module on the blower since the passive components are unlikely to fail, at least w/o being obvious . . . altho if they're marked you could check them. That DVM probably measures capacitance too. Also check the circuit board for obvious issues. You might even try re-soldering it.

If you can get an analog meter, I'll take the time to measure mine for comparison.

 

Thanks Rick. The Fluke manual is where I saw it's capabilities. That meter is pretty powerful.

Yes, the ac amp looks buried in there. I couldn't even see the thing. If it's broken it'll be one heck of a labor charge.

Fred- measuring the drive signal is what I'm after...guess duty cycle etc. were the wrong choice of words.

Stay tuned.

Eric

 

Fixed!

Thank you Rick, Fred, James for your suggestions. Turned out to be simple...

Got access to an oscilloscope and saw that pulse was there from the ac amp. Plugged in blower and while I was pushing the scope's probe into the connector the blower started up. The connector pin for the signal wire lost it's grip on the blade sticking out of the blower. Twisted the blade some and connection re-established.

Lesson- look at the easy stuff before digging too deep.

Found this great site so wasn't all for nothing.

Eric

 

Eric, I'm glad that you found the problem, and thanks for letting us know what you found. It will probably help some others in the future.

You were lucky to find a scope. My company used to have all kinds of test equipment, but as things went digital and modular, we started to depend on built in diagnostics and card replacements. I don't think I could easily locate a scope any more.

Rick

 

Congratulations, Eric! Sometimes the simplest things can get overlooked--like a bad plug contact. Good thing you stuck with it. Can't imagine what the dealer would have charged to fix it!

 

Yep, the old twist-the-pin trick. Like Junebug says what would a dealer charge ... $1000 diagnostics to find it, no charge to twist the pin.