Cooling fan not kicking in

[chris_fz6]

Can someone shed some light at why would my radiator fan not kick in please?

Bike is FZ6 2008

I have now tested and replaced everything on the radiator fan harness side and the fan still doesn’t kick in at 100C (212 Fahrenheit).

Tried new (used) cooling fan.
New relay.
New cooling fan fuse.
New temp sensor/switch.

Still doesn’t kick in at 100C

One weird thing I’ve noticed is that while measuring the voltage at the fan plug it’s only around 9 volts(first photo). Is this expected?

Second photo is measuring the voltage at the relay plug where power comes from battery(pin 87 and 30) on the diagram and I’m getting the exact same readings of around 9 volts. (Previously tested the fan by connecting it straight to the battery and it works every time).

Any idea if 9 volts is how much should go to the cooling fan? And if that’s not normal what could be the issue?

Thanks in advance.

 

[Motogiro]

Welcome to this great forum!
If you look at the wire colors, at the fan relay, you should see 12 vdc on the brown with black tracer wire and the red with white tracer wire while the ignition key is in the on position. With the key in the off position you will see 12 vdc on the brown with black tracer wire but not on the red with white tracer.
The relay coil is operated by the ECU which provides the ground path for the relay coil. This is the green with yellow tracer wire. If you ground the green with yellow tracer wire the relay should operate but don't ground that wire while it's still connected to the ECU. You could disconnect that wire from the relay, turn the key to the on position and then ground the green with yellow tracer wire. If the fan comes on it will prove out the relay and supply voltages.

Let us know what you find.

 

[Motogiro]

Any progress?

 

[chris_fz6]

Hey Motogiro.

Thanks for your reply.

I was hoping I'm close to fixing the issue, however, when I tried again yesterday, now my Headlight doesn't work as either. No high beam, nothing.

I'm not sure what's happened. I tried to bridge both relays (took the relays out and bridged pins 87 and 30) still no fan or headlight working.

The only thing I can think of is I wiggled the harness going to both relays the day before hoping that would fix the issue with the fan(silly me). Not sure what's happened. Maybe I broke the earth/ground?

 

[Motogiro]

There is a headlight relay. The ECU controls the headlamp relay. The engine must be started first before the headlight relay will be activated by the ECU. This catches many people when they are working on the bike. If you're working on the headlight circuit and need to test it, you can start the engine so the relay becomes active and then turn the engine off by using the red kill switch to stop the engine and the headlamp will remain active until you turn the ignition key off.
As far as your relay pin call out, I would use the wire color codes to do your trouble shooting. This will help insure you're working on the circuit for the fan relay. As I've said before, you should use caution when testing the control side of the relay because of integrated control by the ECU. You don't want to damage switching transistors in the ECU.

 

[chris_fz6]

Thank you.

The control side is working as expected as I can hear the headlight relay clicking when I turn the ignition on. The issue seems to be with the load side of things as even if I try to short the control pins of the relay plug with a paper clip, there is still no power going to the fan or headlight but there is power going to the relay load pin 87. So I guess the only thing left is the earth/ground not working. Do you know where the earth for the headlight and fan are on the bike frame and how to test it?

 

[Motogiro]

There may be a few different engine/frame ground paths to check.

 

[trepetti]

Thank you.

The control side is working as expected as I can hear the headlight relay clicking when I turn the ignition on. The issue seems to be with the load side of things as even if I try to short the control pins of the relay plug with a paper clip, there is still no power going to the fan or headlight but there is power going to the relay load pin 87. So I guess the only thing left is the earth/ground not working. Do you know where the earth for the headlight and fan are on the bike frame and how to test it?

Just an FYI, the headlight relay does not click when the ignition is turned on. It only activates when the ECU thinks the engine is started. Only then does the ECU provide ground to the relay coils, causing the relays to close.

 

[TownsendsFJR1300]

Long time, no hear Tom.. You doing ok?

.

 

[chris_fz6]

Just an FYI, the headlight relay does not click when the ignition is turned on. It only activates when the ECU thinks the engine is started. Only then does the ECU provide ground to the relay coils, causing the relays to close.

So the relay side of the headlight doesn't actually play any role in the headlight coming on, it actually turns it off when the bike cranks if I understood you correctly? Does the load/power to the headlight go through the headlight relay at all or is it a different circuit?

 

[Motogiro]

The power to the headlight goes through the headlight relay. There is no power to the headlight until the relay coil activated. When the key is in the on position power is applied to the relay's positive side of the coil but the coil negative side is not grounded until the ECU grounds it. The ECU does not ground the negative side of the coil until the engine has been started. This means there is no power to the headlight when the key is in the on position or when the starter is energized. The ECU likely is coded to ground the headlight relay coil after the ECU sees an RPM threshold count from the crankshaft position sensor.

The fan relay works on the same basic principle of no operation of the relay until the ECU provides a ground path for the negative side of the relay coil.
If the ECU is damaged it may have lost the ground path internally and that is why you have no relay operation on the headlamp and fan relays.
Check the ECU plug. Inspect that all the pins are present and clean. If the engine runs the ECU has a ground. The internal ground path within the ECU may be bad but you should test your fan relay per my description in post #2.

 

[chris_fz6]

The power to the headlight goes through the headlight relay. There is no power to the headlight until the relay coil activated. When the key is in the on position power is applied to the relay's positive side of the coil but the coil negative side is not grounded until the ECU grounds it. The ECU does not ground the negative side of the coil until the engine has been started. This means there is no power to the headlight when the key is in the on position or when the starter is energized. The ECU likely is coded to ground the headlight relay coil after the ECU sees an RPM threshold count from the crankshaft position sensor.

The fan relay works on the same basic principle of no operation of the relay until the ECU provides a ground path for the negative side of the relay coil.
If the ECU is damaged it may have lost the ground path internally and that is why you have no relay operation on the headlamp and fan relays.
Check the ECU plug. Inspect that all the pins are present and clean. If the engine runs the ECU has a ground. The internal ground path within the ECU may be bad but you should test your fan relay per my description in post #2.

Thanks Motogiro.

Everything on the bike runs as expected apart from the cooling fan (and now the headlight). I even rode 30 miles today without an issue. Hence I don't think it's the ECU (Also, don't think it's the ecu as I can hear the fan relay clicking when the temp goes to 100c).

From what I'm reading, the ECU just energises the relay on two of the pins (85 and 86) which through magnetism bridges the path of pins 30 (the power from the battery) and pin 87(the cable going to the fan that provides the voltage). The fan has its own ground (I guess the headlight does too) which I suspect they have lost. So I'm going to try and find where the grounding points of the fan and headlight are.

For a test tomorrow, I'm going to run a ground from the battery to the fan plug, if the fan spins, I guess I've proven that lost ground is the issue.

Is my thinking correct?

 

[chris_fz6]

Does any of you knowledgable lot live around West London/Berkshire area? I'd rather let someone more knowledgable than me have a look as well. Of course I'll pay

 

[Motogiro]

Thanks Motogiro.

Everything on the bike runs as expected apart from the cooling fan (and now the headlight). I even rode 30 miles today without an issue. Hence I don't think it's the ECU (Also, don't think it's the ecu as I can hear the fan relay clicking when the temp goes to 100c).

From what I'm reading, the ECU just energises the relay on two of the pins (85 and 86) which through magnetism bridges the path of pins 30 (the power from the battery) and pin 87(the cable going to the fan that provides the voltage). The fan has its own ground (I guess the headlight does too) which I suspect they have lost. So I'm going to try and find where the grounding points of the fan and headlight are.

For a test tomorrow, I'm going to run a ground from the battery to the fan plug, if the fan spins, I guess I've proven that lost ground is the issue.

Is my thinking correct?

If you run negative to the relay it must only be on the negative side of the relay coil. I would also disconnect that negative wire on the ECU control side. If you ground that wire but the potential at the ECU is held positive you could damage the ECU. So to explain, the ECU may not be an open circuit on the ground path for those relay coils and may in fact be a positive voltage. This means if you physically ground the control wire while it is attached to the ECU you could cause damage.
So I would confirm you have the correct relay by the wire color codes. Detach the negative wire so the ECU is not attached. Ground the negative side of the relay coil. You should hear the relay click and the fan should come on. Try this first.
I would also check your headlamp circuit fuse.

 

[chris_fz6]

If you run negative to the relay it must only be on the negative side of the relay coil. I would also disconnect that negative wire on the ECU control side. If you ground that wire but the potential at the ECU is held positive you could damage the ECU. So to explain, the ECU may not be an open circuit on the ground path for those relay coils and may in fact be a positive voltage. This means if you physically ground the control wire while it is attached to the ECU you could cause damage.
So I would confirm you have the correct relay by the wire color codes. Detach the negative wire so the ECU is not attached. Ground the negative side of the relay coil. You should hear the relay click and the fan should come on. Try this first.
I would also check your headlamp circuit fuse.

Apologies, my explenation wasn't very good. I'm not going to run a ground wire to the relay plug/contact, I'm going to run a ground wire form the battery negative terminal to the cooling fan plug/contact (they are next to each other). It's after the cooling fan relay, located on the left hand side of the battery. Where the cooling fan plugs, there is the blue load 12v wire coming from relay and there is a black ground wire. My suspicion is that the black/ground wire has lost earth, hence the fan not spinning. I suspect the same earth goes to the headlight, which earth wire is now bad too.

Does that make sense?

 

[Motogiro]

Apologies, my explenation wasn't very good. I'm not going to run a ground wire to the relay plug/contact, I'm going to run a ground wire form the battery negative terminal to the cooling fan plug/contact (they are next to each other). It's after the cooling fan relay, located on the left hand side of the battery. Where the cooling fan plugs, there is the blue load 12v wire coming from relay and there is a black ground wire. My suspicion is that the black/ground wire has lost earth, hence the fan not spinning. I suspect the same earth goes to the headlight, which earth wire is now bad too.

Does that make sense?

Yes that makes sense. If that ground is related to the headlight ground you'll see it as soon as you start the engine and the headlight circuit becomes active. You could jump the black wire at the headlight to negative at the battery. Make sure it's not the black with yellow or green tracers.

 

[chris_fz6]

Yes that makes sense. If that ground is related to the headlight ground you'll see it as soon as you start the engine and the headlight circuit becomes active. You could jump the black wire at the headlight to negative at the battery. Make sure it's not the black with yellow or green tracers.

That makes sense. I couldn't connect the wire to the fan connector(I'm a novice in vehicle electrics). It kept popping out of the connector. What I did though is check for continuity at the black ground wire of the fan connector with one of the probes of the multimeter and the other one on the negative battery terminal while the bike was running and there was no continuity (the multimeter didn't beep) so I guess that proves that the fan connector has lost its earth. Isn't it?

 

[Motogiro]

Sound like you're on the right path. You've likely lost a chassis connection. That loss could be through a plug. There is at least one frame connection that I remember when I have the FZ6. You'll find. Take your time. As soon as you relax and take a deep breath you'll find it! Lol!