B1497 - Communication Malfunction (Bus IC) - need help

Each servo is really simple. You can see it diagrammed up in post #2. It is nothing but a motor and two switches. Five pins: two for the motor, one common to both switches, one for each switch.

If you apply 12 volts to the two motor terminals and the motor turns, and turns the other way with the polarity reversed, and the two switches toggle between open-circuit and closed while it is turning, it's doing everything it's supposed to.

 

I have removed the air mix servo and put it aside. I am now adjusting temp from the cog manually. Pretty easy to get to while sat on drivers seat on rhd.

I removed dash and noticed the air direction flap is broke in the heater box. I can tell the dash has been off before as it had a bolt missing. So even if the servo was working this flap will not move. I left a 3mm gap on the centre flap and then screwed a screw in acting as a stopper. So the majority of the air is directed to the windscreen and a little coming from the front vents. I couldn't work out how the air is directed to the geet vents.

Top 2 servos look impossible to get to even with dash removed on rhd. I noticed when I boxed everything back up that I can get to to them quite easily if I remove the park brake lever out the way. (Smacky forehead moment right at the end! Lol) glad I removed the dash though as otherwise I would have never known about the cracked flap.

Thank u, I will try powering up the servos in next few days. The amp is being sent back and another with matching part numbers is being delivered.

Dash removal wasnt too bad of a job. But I'm not looking forward to replace the whole heater box, as it looks like alot more has to be removed just to get at it

 

I found this online.

Is it possible to check pulse with a digital multimeter?

 

What you found there doesn't pertain to testing the servos, but to the interface between the amplifier and the bus ICs built into the wire harness. That's a serial communication link, a fast stream of bits. You might be able to use a multimeter to see that something was happening, but you'd need an oscilloscope or logic analyzer to see the bits go by.

 

I think we would have a fault code for a bad servo rather than a communication fault, if a servo upto was the fault. I will try testing my motor tonight. Currently happy that I can use the car again so will update u guys once I do get the right amp. If new amp dont work then I will test as in the method I found. And find someone with oscilloscope to check pulse.

 

Hello everyone!

I stumbled across this forum since I had the same issue with a B1497 DTC on my 2007 Toyota Camry with automatic climate controls. I had tried replacing both the servo harness and the ac amplifier, but the DTC still wouldn’t go away. After bringing the car to an automotive electrical repair shop, it turns out that my problem was a blown fuse and a short somewhere on my harness (not the servo harness but the other harness since my car originally didn’t come with automatic climate controls). Long story short, the OP probably has a blown fuse. I hope this helps!

 

Do you remember what fuse it was ? I’m currently having this same problem

 

Sorry to join in but I’ve half way fixed my problem using what’s been said so far.

I had the same code b1497, I reasoned that to fault find properly I needed another amply and the three actuators and found a whole set on eBay for £70.

I also got a copy of techstream and have started to play. I found a reset on the aircon amplifier but it didn’t seem to do anything, swapped to the replacement and it did the reset ok but nothing moved, not even a flutter. The test screen lead me. Wild goose chase looking for a “servo motor ECU” and spend serval days trying to find it and where it was fused, gave up on the and went fuse hunting starting under the bonnet, one fuse at a time, found a fuse in the wrong place 14 should have been in 15, so someone has tried all this before explains so much.
So far most things are working but looks like I’ve mucked up one set of blending flaps so that tomorrows job so taking the top of the dash off.

thank you for all the input so far