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Discussion Starter · #1 ·
Hi guys,

I´m working on a friend´s B4 989R and the problem started a few days ago when coolant came out the "trop plein" pipe as temperature sky rocketed till 120ºC.
It only happened on a stand still or riding in traffic.
I rode it a few kms before I could diagnostic the problem. The fans works at a stand still, starting at 96ºC, I would say twice, and then they just won´t work when it reaches 96ºC again.
What can cause this random error from the fans?
Could it be the fans relay that "sticks"?
I thought of the temperature sensor but it reads temperature just fine...
 

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Discussion Starter · #2 ·
So...I just checked the circuit line from the fans to the relay and reached the conclusion that there´s no relay. It appears to go straight to the black fuse box (SPU?) on the right side of the bike. Is it possible that this SPU is some way damaged?
 

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Um, yes... there are many, many threads on SPU failures due to heat build-up.

 

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There are 2 temp sensors...one is for the meter, the second for the ECU, which then controls the fans.

I have seen several examples with the 910 (same basic system) where one side of the sensor was faulty. In these cases it was the meter side and the meter would read very high temps even though the bike was not actually overheating.

So you can still have a faulty sensor. There is a test procedure detailed in the manual.
The later model SPUs are not as failure prone as the early ones.
 

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@Gilles - What year is your 989R? Help us help you.
 

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Discussion Starter · #6 ·
There are 2 temp sensors...one is for the meter, the second for the ECU, which then controls the fans.
Nop. The 989 does not have a temp sensor on the radiator as the other 4L MV´s. Don´t ask me why...
 

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Discussion Starter · #8 ·
Guys, just found this connector on the left side of the bike, with sliced wires (from rubbing against the fan). The wires come from the lower section of the engine...
487625
487626
 

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It´s a 2009 unit.
What is the tenth digit of your VIN?

What was that connector plugged into?

The 989R is by all information a MY 2008 machine.

The 989R has two fans and two temperature sensors...one for ECU(CPU) input and one for Instrument (Dash) input. It is hard to tell the wire colors from the wiring diagram for the 989R, but in this respect, the wiring diagram from the 05/06 910 is the same and has a clearer picture of wire colors.

487631


487629


487632
 

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Discussion Starter · #10 ·
VIN -> ZCGF412AA9V013279

Where is that #22 water temp sensor on the bike?!

Anyway, thanks for your help!!!
 

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Nop. The 989 does not have a temp sensor on the radiator as the other 4L MV´s. Don´t ask me why...
It is a single sensor mounted in the cylinder head with 2 separate circuits. One for the dash and one for the ECU....
One side can fail while the other is fine. The 910 has the same set-up as the 989 1078 etc...

But it appears the case is solved it is always something simple.
 
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The wire colors do not match that connector.....
 

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Discussion Starter · #13 ·
I only see this temp sensor...
And it makes sense because it has 4 wires!
I think I will start with a New water temp sensor!
487635
 

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Discussion Starter · #14 ·
The wire colors do not match that connector.....
Just found out that these wires are from an aftermarket gear indicator... that´s why I didn´t find it anywhere on the schematics! :rolleyes:
 
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Old Wing Nut
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I only see this temp sensor...
And it makes sense because it has 4 wires!
I think I will start with a New water temp sensor!
That's the one !! You can test it. Just need a pot of water on a hot plate with a thermometer and an ohmmeter. Check the manual for details.
 

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Hey, you can go read my latest post and it’s a similar issue if it might help at all.
 
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