09 Yaris Heater blower problem

[motoxxx3]

I have just taken a look and directly underneath the airbox/ducting there is what looks like a silver module bolted to the floor directly behind the centre console.....printed on it - 'Made in U.K.' so it is likely to be be faulty
I will be annoyed with the dealer if it turns out it is this because it looks pretty easy to change..and they could have tried one off of another Yaris.
It's driving me nuts! it is as though somebody is constantly turning the blower speed up and down as Iam driving along

[CTScott]

Originally Posted by motoxxx3

I have just taken a look and directly underneath the airbox/ducting there is what looks like a silver module bolted to the floor directly behind the centre console.....printed on it - 'Made in U.K.' so it is likely to be be faulty
I will be annoyed with the dealer if it turns out it is this because it looks pretty easy to change..and they could have tried one off of another Yaris.
It's driving me nuts! it is as though somebody is constantly turning the blower speed up and down as Iam driving along

If the silver module has yellow connectors then you are looking at the SRS ECU (for the airbags). The AC amplifier is black and has one or two (depending on the configuration) white connectors.

[motoxxx3]

I have had another look, and the only other thing I can see is a black module with 'fins' on it. It is in bolted to the firewall in the centre of the car - directly in front of the silver SRS ecu behind the centre console.. difficult to see colour of the connectors/wires though. There does not seem to be any module mounted on the firewall in the drivers or passenger side footwells.
I just discovered last night & this morning that it seems like if Iam driving with the car's lights on the heater blower runs at it's correct speed all the time and does not fluctuate with accelerator position. If I turn the lights off it starts to fluctuate again.
Iam going to try this again over a longer period just to be sure.

[CTScott]

Originally Posted by motoxxx3

I have had another look, and the only other thing I can see is a black module with 'fins' on it. It is in bolted to the firewall in the centre of the car - directly in front of the silver SRS ecu behind the centre console.. difficult to see colour of the connectors/wires though. There does not seem to be any module mounted on the firewall in the drivers or passenger side footwells.
I just discovered last night & this morning that it seems like if Iam driving with the car's lights on the heater blower runs at it's correct speed all the time and does not fluctuate with accelerator position. If I turn the lights off it starts to fluctuate again.
Iam going to try this again over a longer period just to be sure.

Here's a picture of where it is located on my LHD Yaris. I believe that it is a mirror image of this for RHD cars.

AC Amplifier Location.jpg

Looking at the European EWDs, yours definitely has one (even though it doesn't have A/C). The AC Amplifier has inputs from the headlight switch as well a from the alternator, that let it adjust the heating or cooling operation relative to those inputs. So, the problem being related to having the headlights on or off is quite plausible.

[motoxxx3]

Thank you very much for posting the photo.
You can see from the photos of my car that it is different to the U.S. spec car with aircon.
If my vehicle does indeed have a heater amplifier that is connected to the lights it is looking highly likely that this is the faulty component.