Radiator fans not starting

Hi All,

I’m having a bit of a issue with my S4R (996). The rad fans will not start when the coolant gets to 102c. I’ve tested the fans and they work perfectly fine as they start if I disconnect the plug from the rear coolant sensor.

I’ve contacted the garage that I bought the bike from as it’s still under warranty and they have been very helpful as I live so far away from them, they have sent new parts for me to fix it. I’ve replaced the rear coolant sensor as I assumed that it had failed as it was also running a little rich when it was warmed up. The bike is now running perfectly, but the fans still won’t start when the coolant gets to 102c. If I unplug the connector to the sensor the fans start straight away.

I assume I can rule out any issue with a relay as they start.

I’ve traced all the wiring back to the ecu and it’s all testing ok.

Has anyone encountered this issue before, as I’m all out of ideas?

Thanks for your help in advance.

Adam

[Mark64]

Hi Adam, I've had my s4r for 6 years now & never had the fans come on, it normally runs at around 80c but it's been over 100c in heavy traffic, I can only assume it's a very efficient cooling system.

Good choice by the way.

Cheers Mark, my only worry is that in the service manual it states that the left one comes on at 101c and the right at 102c. It’s risen up to 112 when it boiled over. The engine seems fine and hasn’t done it since, but just worried as we come in to the hopefully warmer months it will get worse.

It’s a fantastic bike to ride, even though it does scare me a little even after a month of owning it.

I’m hoping to pick up a diag lead for and see if there are any issues.

I’m fairly handy with the spanners and always like my vehicles running spot on, but just worried that it’s going to cause further damage.

Or could it be that I’m worrying over nothing?

[slob]

any help?
http://ukmonster.co.uk/monster/showpost.php?p=386681

Cheers Slob, I have tried this with the old sensor and it was way out, so have put a new sensor in and the bike is running much better as from what I understand the rear sensor also affects the fuelling and ignition too.

Just seems very odd that it’s running better but the fans don’t work.

Is there anyway of adjusting the threshold that the fans kick in on the ecu, as I understand the fans are controlled by the ecu rather than the old school was type sensor that would trigger a relay.

[slob]

that’s beyond what i know, i’d ask avanti race parts, he’s the man when it comes to M5.9 ecu stuff

[mickj]

Will tuneecu work with the bike as you will be able to test the fans and temp with the bike running, if it will work could be worth a try.

Cheers guys. I’ll see if Tuneecu works on these ecus, I’ve not used it before but I’m sure I can have a little poke around. I can’t see why anyone would want to change the threshold that the fans kick in.

On a run the temp seems to sit at about 67c which seems a little low to me, but performs perfectly fine.

[350TSS]

Maybe the gauge is reading wrong???

Good idea. I didn’t think of that. I’ll swap the sensors round and see if it changes

[DaveR]

Adam
My fans haven't come on since I unplugged them when I removed the radiator to repair it. I'll now check that sensor to see if that is an issue. I'm still learning my way around the bike electronically as never had one with an ECU & all these sensors before.
67deg is pretty normal for a running temperature this time of year. They run quite cold in the cooler weather, but do warm up quickly when it's hot

Dave

Cheers Dave. They are fantastic bikes even though it seems like a bit of handful at times ��

I’ve swapped the sensors round and still the same.

I know that these both are working as one is brand new and also using the suggestion from Slob.

I’ve realised that there is no cat on the bike or lambda sensor, which makes me think it has been remapped at some point. I wonder if the coding could have been changed or misconfigured which could be causing the fans to not start when hitting the required threshold.

[chris yeatman]

My fans both start working at 105 if thats any help

Cheers Chris. My temps went up to 107 today and no sign of fans turning on �� I’m just worried that it could be a sign of something else happening or it could just be me being worried and just the fans not working

[Darren69]

I've had the same issue with my S4 since I got it. Fans didn't come on at the prescribed temperature, in fact I don't think they have ever come on while riding the bike, despite the temp exceeding the limits. This I should add was before I fitted the oil cooler which helped massively. Shouldn't be an issue on the S4R though.

I have been assured they are set correctly by Neil at Cornerspeed who had his factory diagnostic gear on it and I had also done the same with DucDiag at home so there is not a problem. Neils diagnosis proved interesting since he said the 2nd fan driver in the ecu must be faulty. I did some digging of my own and found that the ecu fitted to my bike was in fact incorrect.

When I got the bike the fans on mine were hard wired together with some home brewed wiring bodge and because of that would not work. I split the wiring join and 1 fan would work fine.

This was because there was an issue with one of the fan drivers on mine because it is an '02 S4 Fogarty model which had the #02 S4R wiring and should have had the #02 S4R DP ECU but because of the fact they were built away from the main assembly line hey fitted the '01 S4 DP ecu in error, which did not have 2 fan driver circuits. So the other fan on mine will never work with the current ecu.

I'm not sure why it wouldn't work with them both wired together and I think the Ducati tech who bodged the wiring expected them to both work too, but for some reason they didn't. I tried all the same things as you too; disconnect the sensors etc so I feel your pain, I've been there but afail the S4R should be ok and both fans should work correctly but good luck testing them.