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Discussion Starter #1
Got a service with the new(ish) Scottish MV dealer and I had them look at a non-functioning rad fan that died relatively recently.

Obviously I'd checked the fuse myself and it's not that.

They say that they can manually switch the fan on when logged into the ECU - so it works and the relays, fuses etc must work. The temp sensor is also reporting sensible values.

But the bike won't switch the fan on when it gets hot enough (I think they mentioned 102 degrees C as the set value)

They were stumped and have asked MV for guidance, but just in case it was something that anyone else has come across?
 

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If fan wiring and fan are proved ok it must be a signal problem so I would replace the sensor as first trouble shooting. Shorting out sensor wires will make fan run and prove its a sensor issue.
 

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Discussion Starter #3
Sensor is reporting sensible values to the ECU supposedly though - as they could tell me what temp they let it get to.

Unless there's a separate sensor for fan activation that differs from the dash display? I'll check the manual
 

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I was having issues with the fan/temp on the Turismo, turned out it was the sensor by the headers which was matted in rubber from the radiator cap, had both replaced and now running sweet.
Hope it's an easy fix mate.
 

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Discussion Starter #5
Yep - looked at the manual to find two sensors, one in the head as Red says and one in the rad end tank. Next job, whip off the fairings and test the sensors (resistance values are given in the workshop manuals) and short out the plugs to see if that prompts the fan to come on. One would hope the dealer had tried this, but just to be absolutely sure for myself.

Streetrider - the sensor in the head is to the right hand side of the bike, you can see the plug going into it just above the headers when you peer in the right hand air outlet in the fairing.
 

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Discussion Starter #7
Just to update, the sensors tested okay for resistance, certainly at ambient, so current thinking is wiring issue.

Bike's going back in to dealers for an extended stay so they can strip and check.

Just out of interest, from my unplugging session, it looks like the one in the head feeds the dash and the one in the rad might be what the ECU uses to determine fan activation (which makes sense)
 

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Had the same problem, changed both sensors and the fan is now working correctly after this even on realy hot day, as long as the bike was not standing still I had no issues with temp, unitl as was stuck in traffic yam in Stockholm
The sensor seamed to get the right reading in the computer, good luck
 

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Discussion Starter #9
Thanks - current thought is that one of the sensors was slightly out of calibration with the other. So awaiting that arriving for them to change it out and try. Hopefully we don't have to change both as that'll be another parts wait!
 

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Discussion Starter #10
Just to update and close this off - it was sensors. Whilst the dash was reading right, the one in the rad tested a bit out of sync with the one in the head, so both were swapped out. Problem gone.
 

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unreal..
i have the same issue.
ts fine riding.. but the fan doesnt come on at a stand still.
i only got 1000K miles on it but now that I think of it, this hasnt worked from day one, if the fan is supposed to come on
at the half way mark. My fan works.. easy check is to connect a 9V battery to it.. the connector is just behind the feiring on the left side.
 

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Discussion Starter #12 (Edited)
When you say it's fine riding, do you mean the temp is fine because of airflow, or the fan will come on when moving?

As you can test the fan is physically working, I'd suggest given the experience here that you swap out both sensors as they won't be expensive (I got mine under warranty). I tried shorting the plug for the sensor to replicate a high state, but that just threw a dash error, as clearly the ECU wasn't seeing logical values over both sensors.

Also, from memory on mine, it'll get a bar above mid-way before kicking in. But without the fan it can get pretty high pretty quick (even in Scotland) and I had to kill the engine in traffic a couple of times
 

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When you say it's fine riding, do you mean the temp is fine because of airflow, or the fan will come on when moving?

As you can test the fan is physically working, I'd suggest given the experience here that you swap out both sensors as they won't be expensive (I got mine under warranty). I tried shorting the plug for the sensor to replicate a high state, but that just threw a dash error, as clearly the ECU wasn't seeing logical values over both sensors.

Also, from memory on mine, it'll get a bar above mid-way before kicking in. But without the fan it can get pretty high pretty quick (even in Scotland) and I had to kill the engine in traffic a couple of times
yes. its fine riding because of air flow..

i was going to try jumping the sensor in the radiator .. I assumed it was an off/on switch and not a variable sensor..
not sure why MV would use to variable sensors..
if there is one in the block for the ECU/dash then they should have used an off/on thermal switch in the radiator..
that is how the automotive business has done it for years until recently..
in some cases they use 1 sensor.. it tells the ECU the temp and the ECU controls the gauge and the fan based on that.. instead of a separate circuit with a relay.
 

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Discussion Starter #14
Sensors are the same in the head and the rad. No idea why one isn't a simple temp switch as you say, but it's the way it is - for sure as I measured cold resistance myself and it's the same on both.
 

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Sensors are the same in the head and the rad. No idea why one isn't a simple temp switch as you say, but it's the way it is - for sure as I measured cold resistance myself and it's the same on both.
unbelievable..
so that means I cant jump the sensor on the radiator.

does anyone know what resistance numbers I should see on cold or normal operating temp ?
 

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ok.. sensor seemed to be normal..
I went to put antifreeze in the over flow tank and wouldnt that epic design FAIL...
the nut that is moulded into the inside of the tank is just spinning. Not sure why a simple cap or rubber plug wasnt used
like every other overflow tank in the history of over flow tanks.
so now I need a new over flow tank.

the good new is I got the fan to come on.. very temperamental system.. I took the radiaotr cap off and added some antifreeze.. maybe a cup full at best? now the fan is working fine..
im not sure I will go thru the trouble of replacing the tank.. might just take the hose off where it connects to the radiator neck and force antifreeze into the tank..
 

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Drill the hole to a bigger size ...
Drilling the brass insert will just make it spin better in the thin plastic wall of the overflow bottle!
...Not sure why a simple cap or rubber plug wasnt used
like every other overflow tank in the history of over flow tanks.
...
Look under the front of the gas tank.
second pic; a plastic cap!

...im not sure I will go thru the trouble of replacing the tank.. might just take the hose off where it connects to the radiator neck and force antifreeze into the tank..
A funnel and nimble hands.
The overflow drain that spits out the excess coolant can be used to refill the overflow tank.

Fill her up over the min mark and the excess coolant will use that very same route to spill under the bike.

From the coolant reservoir topic below I gather that a new bottle isn't that expensive AND AVAILABLE.

Radiator screw cap valve might get stuck and could be another suspect.
 
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