Radiator fan not engaging at high temperature | GTAMotorcycle.com

Radiator fan not engaging at high temperature

matthew

matthew

Well-known member
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1997 CBR 1100
120,000 km.


My fan did not kick in on a recent ride. The temperature gauge almost hit the red mark.

The fuse is good. There is coolant in the reservoir. The fan is not physically stuck.

I tried to ground the fan, bypassing the thermo switch on the rad. No effect.

I've followed this video, even though it's for a CBR F3, and still no effect;



I'm not seeing 12v on my multimeter. I'm seeing somewhere between 1 and 3 volts

Is there anything else I can try or can I conclude my fan is pooched?
 
need a schematic to see how the fan motor is powered up
it's probably though a relay controlled by the temp switch
providing ground to the motor may do nothing if the relay supplies 12 V
 
My money is on bad wire or bad relay. Work on getting 12V (and ground) to fan motor first, then track down any additional problems.
 
J_F said:
need a schematic to see how the fan motor is powered up
it's probably though a relay controlled by the temp switch
providing ground to the motor may do nothing if the relay supplies 12 V
Click to expand...

The service manual should be available through my Dropbox

Dropbox - File Deleted - Simplify your life

www.dropbox.com www.dropbox.com

The wiring is page 445 of the PDF. 19-24

From what I can see, there's no relay for the fan.

I know I had issues with tie ignition wires a few months ago and I needed to solder them back onto the barrel. I can't help but think that may be the cause of my issue, based on what I saw in the manual

1593140998495.png
 
matthew said:
The service manual should be available through my Dropbox

Dropbox - File Deleted - Simplify your life

www.dropbox.com www.dropbox.com

The wiring is page 445 of the PDF. 19-24

From what I can see, there's no relay for the fan.

I know I had issues with tie ignition wires a few months ago and I needed to solder them back onto the barrel. I can't help but think that may be the cause of my issue, based on what I saw in the manual

View attachment 43766
Click to expand...
That's a solid lead. Power coming from a place where you had an issue and fiddled with it. Depending on how tired that cylinder is, it may be simpler to power the fan through a relay that picks up power from a more accessible location.
 
from your PDF
sounds like the last paragraph covers your problem

RM7VHrU.png
 
If it was a Beta I would say your rectifier is shot, but it's not so I would start by putting 12 volts through the fan and see if it spins ;) now you know the fan is good so it has to be wiring.
... come to think of it that is the first thing we tested on the Beta too.


... and I'm betting on the fan being good, because I doubt that bike outputs sufficient power to cook that fan to begin with.
 
Last edited:
The blackbird is a marvel of engineering. I also doubt it's the fan. I'll muck around with it this weekend
 
fwiw: I always start with the source, once you have the meter in hand and the bike even runs, why not begin at the alternator output and work down stream.
 
Trials said:
fwiw: I always start with the source, once you have the meter in hand and the even bike runs, why not begin at the alternator output and work down stream.
Click to expand...
In this particular case, he knows he has 12V at the switch as the bike runs. That appears to be the supply for the fan and he was soldering in there recently. If you have 12V there, you don't need to look upstream yet.
 
Is it a 3-phase alternator?
How does everyone else test if one coil out of three in a three phase alternator, is putting out the correct voltage :unsure:
12 volts DC is measuring the voltage to and from the battery.
 
Trials said:
Is it a 3-phase alternator?
How does everyone else test if one coil out of three in a three phase alternator, is putting out the correct voltage :unsure:
12 volts DC is measuring the voltage to and from the battery.
Click to expand...

Most, but not all, modern bikes have a 3 phase alternator. if you have three wires coming off the stator, you have three phases.
In your manual you will find procedures to test for stator impedance and ground faults.
The "quick and dirty" test: Just measure AC voltage at the stator output. You should get three readings VERY close to the same, across the three different combinations of the three wires. You WANT about 70 volts AC at 4500 RPM.
In a 3 phase system, one phase can have enough AC power to show 12 volts AFTER the reg/rec, but it will be lacking amperage... which you are not equipped to measure. So if you have a stator problem, you can have 12 volts DC after the reg/rec BUT it won't have enough amperage to charge the battery.
 
This is a easy problem to rectify. You must start with the end and work your way back.

Fan - does it work with 12V input - Yes / NO
Trigger - what triggers the fan - Thermal switch - Is it within range - yes/no

If both components are working, you must look at what else is in the circuit to complete it.
 
SOLVED (sort of)

another broken ignition wire. Blue / Orange wire from the ignition barrel leads into the 10a fan fuse which leads to the fan.

Thank you for your help everyone.

Now it's time to take apart the front end and get to the ignition, again.
 
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