As mentioned in my previous post, my radiator fan did not work after installing the Link (same with A/C). After doing some googling, I suspected the fans could’ve been locked out due to no A/C gas.
Looking at the wiring diagram for the fan setup on an earlier model Swift Sport (ZC31S) I decided this was unlikely. I had the A/C gas reinstated and there was no change. Notably, the A/C compressor requires jumping to trigger.
Reviewing the diagram, I believe there is something internally inside the ECU that is unhappy with the “IGN ON” state. Refusing to trigger (pull down) the outputs to the radiator fan and A/C compressor relays. – refer green “fucked?” circles. I discuss more about it in this post I made on the Link Forum.
Above image is how I ended up wiring the fans via the Link, it works perfectly! On low speed, at idle the fan was able to drop the temp nicely. As we enter the depths of Summer it will be good to see how high speed goes. My logic for fan control is below. Note, the image of the laptop below doesn’t show current settings.
LOW: Coolant temperature > 93C (3C hysteresis)
HIGH: Coolant temperature > 100C (4C hysteresis)
Unfortunately, I am now out of aux outputs and will require one to get A/C working via the Link (if I choose to do so).
I have a few options for triggering the A/C compressor. The factory ECU appears to trigger the compressor relay output when receiving a CAN message from the press of the A/C button in the car.
From my research, I believe the car (and most late model Suzuki’s) runs the bus on 500Kbp/s. As I have the CAN lambda installed on 1Mbp/s, I would need to drop the bus to 500 Kbp/s and sniff out the A/C request in order to get the Link to control the compressor output. If I go with this option, I will make the Link fan output be single speed, HIGH (Aux 4) and the LOW speed would become the A/C compressor (Aux 5).
The alternative is run a secondary CAN device, such as the Canny C7 which could control the compressor relay output as a standalone device. This could be preferable as the Link CAN bus would be completely separate to the OEM ECU.
Updated wiring table is below.
