Radiator Fan not switching on...leading to overheating

[DaveD]

Hi folks - My bike ('09/40k miles) started exhibiting a similar problem to the one described here: the fan just doesn't switch on at four bars. I read through this thread and it seems spot on with what I need to check - thanks to all who weighed in.

On the diag screen, I used code 51 to test the fan using the Actuator thingy. Tested this way, the fan works fine.

I have two questions about next steps:

- It looks like eliminating the possibility of an air pocket in the coolant might be the next cheapest, easiest step. Is that as simple as running the engine with the radiator cap off? If it's more involved than that, can I get some tips?

- If an air pocket is not to blame, then switching the relay with the headlamp relay to see if that's the culprit is the next step - right?

 

[RossKean]

The Gen II (2009) has more bars than the Gen I. The fans DO NOT come on at four bars. Can't remember the number but it is three quarters of full scale.

 

[MrZappo]

Gen 2. On at 7 bars. Off again at 4.

 

[DaveD]

Thanks for the replies. I used to have a Gen 1 ('04) so it appears I just haven't been paying enough attention.

So if it gets to 7 or 8 bars, that's not something to panic about?

 

[MrZappo]

If it gets to 8 and the fan isn't on, that is an issue.

If it briefly gets to 8 and the fan is on and things start to cool, all is well.

 

[Fred W]

If the fan turns on from the diag menu, that checks out all of the "power" side of the circuit (Fan motor, relay, control signal from ECU). The coolant temp display on the instrument panel is a graphical presentation of the same temp signal that the ECU uses to determine when to switch the fan on and off, so if you are seeing 8 bars on the display and the fan still doesn't come on, but it does come on and off with the diag function, about the only thing left is the software (firmware) running in the ECU that calculates the fan turn on. That would be a very unlikely failure.

 

[DaveD]

thanks, Fred. Sounds like I may have been getting my panties in a twist over nothing. I'll watch it more closely this week, going to and from work. And I plan to drain and replace the coolant this coming weekend - it's been a couple of years.

This is a great forum and resource.