Low speed fan not working on 120 VTI radiator fan

[paulbl]

Hi,

It seems my low speed fan on my 120 VTI 2012 doesn't come on, as I read the OBD coolant temp at around 97c, I even got to 102c (I think the high speed is working, but haven't seen it in action,
just that I never overheat, and the temp drops at around 105c in the OBD sensor reading).

To test the fan, I removed the 2 pin plug from the resistor/relay unit pictured above, and shorted the 2 pins, the fan started, so it is ok
I tested the resistor/relay unit on another friends car, and his low speed continued to work so this unit seems ok.

So what else can I check?
Is the ECU only one controlling this? Is the ecu directly wired to the 4 pins?
Is there another temp sensor but the one on the thermostat housing? If so, which one is reported on the OBD?

And about this relay:
Is this unit just a relay that connects the resistor in series to the 2 pins? What are the 4 pins?
Can it short it as well - high speed mode or is that another relay? If so where's the high speed relay?

Thanks ahead,
Paul.

[Chris_Blue]

what does the temperature gauge read?

My fan pretty much never comes on

[paulbl]

I don't have a temp gauge. Just a warning light (blue led for cold and I it can also light up red for too hot, but then probably other lights will turn on).

I've got the schematic! attached.

It's actually a Citroen C3 vTI 120 1.6 16v... but I understand that under the hood they are the same.

1529 is the unit I pictured in the main post, so it seems to control both speeds via 2 relays,1510 is the radiator fan, 1320 is the ECU, 12A6 is the coolant temp sensor (thermistor) and what I was told is
thermal switch to control the actuation of the coolant pump.

Credit to GiveMeABreak from https://frenchcarforum.co.uk/forum/v...902b849a8a8e16