Radiator fan out

[Westone]

I just found that after a cold start and idling for 10 minutes in 60* temps, the radiator fan on my K75 is not coming on. It seemed warm enough that it probably should have. I have had this bike for about 400 miles and have never noticed any noise from it running, and in fact would never have even though about it except for reading a thread on balancing the TBs which mentioned warming it up until the fan comes on.

The fan seems to spin freely when I reached in there with a screw driver and pushed it. However it is not very accessible and all I really know is that it is not frozen in place.

Any suggestions on troubleshooting it, easiest items first?

Thanks

[johnny]

it may take longer than 10 minutes for your fan to kick on...  did the red temp idiot light on your dash come on...

ibmwr...

j o

[TimTyler]

Choke-up the throttle to high and let it run a little longer.

[Westone]

No, other than the red Brake Light bulb test light, the one with the ! that comes on at start until the hand and foot brake are activated and both bulbs test good, no red light has ever come on.

Does the fan typically make enough noise to be heard over the engine? And will it run after shutdown as it will on some cars? I've never heard it do so.

@TimTyler: Will do, thanks.

[mac]

You can hear the fan, but you have to be listening for it. Not surprised it didn't come on idling in 60deg weather. Mine rarely comes on. I'll hear it sometimes when I'm stuck in traffic in warmer weather.

As for troubleshooting, nothing is super accessible. You can take your pick of pulling the tank to get into the relay box and try to apply power from there, or trying to get at the connector near the fan motor to apply power there.

You've said it's not seized. That rules out one common failure point. When mine stopped working, it spun freely too. It ended up being that one of the brushes on the motor somehow fell out of place. I was keyed into the problem when the idiot light came on in traffic.

If it were me, based on what you've said, I'd wait for more evidence of a problem before tearing into things.

[Westone]

Okay, I'll just stay aware of it and watch for it to be running at some point when it's hot later this year. I thought if it was not moving that the fan should come on once it warmed up, like my car does.

Thanks for the help folks.

[Jeff Sichoe]

Does the Horn work?

The Fan and the Horn are on the same fuse - might help you pinpoint the failure?

Otherwise the Temp light comes on at ... 110c I think? and the fan is meant to kick in after engine temp hits 102c (?? I could be slightly out on the correct temps), so if the light comes on and the fan still isn't running then you got a minor problem.

Edit

Meh: I was close enough, here are the correct specs tho -

Code: [Select]

System Parameters:
Clarence Dold summarized the following for us, according to the 93 K75S Owners' Manual:
Thermostat starts to open at 85 C                (185 F)
Fan Cut-in at 103 C                              (217 F)
Overheat Warning Light at 111 C                  (232 F)
Pressure relief valve opens at 120 C/1.1 bar     (248 F/16 psi)
Vacuum relief (return valve) opens at -0.1 bar   (-1.45 psi)

[Westone]

No, the horn does not work. However, I tested the fuse and it has continuity. When the horn button is pressed, with the ignition on and the engine off, I can here a click from the relay box under the tank, which also indicates the fuse is good.

If the relay clicks audibly when the horn is activated, is that an generally taken as an indication that the relay is functioning properly, or malfunctioned?

And does this mean that the radiator fan and the horn failure are not related?

[JamesInCA]

No, the horn does not work. However, I tested the fuse and it has continuity. When the horn button is pressed, with the ignition on and the engine off, I can here a click from the relay box under the tank, which also indicates the fuse is good.

It doesn't indicate that the fuse (or related wiring) is good. The relay's coil is not powered through the fuse; it's the power switched by the relay that comes through the fuse. The relay clicking tells you that the circuit from the horn button to the relay has continuity. It doesn't tell you if the wire the relay is switching has power on it. The lack of a horn sound, however, strongly suggests it does not.

If the relay clicks audibly when the horn is activated, is that an generally taken as an indication that the relay is functioning properly, or malfunctioned?

It means the relay is likely functioning correctly, although not definitively. It means it is more likely that there is no power on the wire the relay is switching. On my wiring diagram, that appears to be fuse #7. So check for voltage on fuse #7, not just continuity on the fuse.

And does this mean that the radiator fan and the horn failure are not related?

No, it means they likely are related. Both are on the wire that's behaving like it has no power.

[JamesInCA]

Of course it is also possible you have independent failures of the horn and the fan themselves.

The horn is easily tested by wiring direct to a battery. Just be prepared for it not to be broken.  :yow

[Westone]

The relay's coil is not powered through the fuse; it's the power switched by the relay that comes through the fuse.

Ahh. I had it backwards.

No, it means they likely are related. Both are on the wire that's behaving like it has no power.

I'll check for power at the fuse.

[Westone]

Okay, I checked for power at the fuse. Looking at the fuse block, the right side of the Horn fuse connection has ~11 volts (ignition on, engine off), the left side 0.

With my tester jumping across both sides of the Horn fuse connection, ~10 volts flows across, and when I hit the horn button it jumps up to 12 volts.

What does that mean, is that normal? The horn itself is the obvious thing to check, but requires removing pieces of the fairing and I won't have time for that today. I'm not able to get to it even to check for current at it's connection.

Thanks for the help!

Oh, and based on what other people have shared regarding the operation of their radiator fan, there may not be a problem there.

[JamesInCA]

If there's voltage on one side of the fuse but not the other, the fuse is blown.

Just to be certain we're talking about the same thing:

- Set your meter to measure voltage
- Put the black probe against the ground attachment point on the transmission
- Leaving the fuse in place, put the red probe on the left and right sides of the fuse. (Most, if not all, fuses leave a small portion of conductor exposed on each side so you can take this measurement with the fuse in place.)

[Westone]

No, that was with the fuse out. I didn't realize it was possible to check it with the fuse in place. Give me a few minutes, I'll check it again with it in.

ETA: Okay, the fuse is good. It measures ~10 volts on either side of the fuse. So the horn is the next suspect, correct?

[JamesInCA]

No, that was with the fuse out. I didn't realize it was possible to check it with the fuse in place. Give me a few minutes, I'll check it again with it in.

ETA: Okay, the fuse is good. It measures ~10 volts on either side of the fuse. So the horn is the next suspect, correct?

Seems like it. There's power on the wire, so the next likely suspect is the horn itself, the wiring to it (maybe the lead is just detached), or the relay.

Also - 10V is low. I don't know if it's low enough to not actuate the horn, but it's not what it should be (>12V). Maybe someone else can chime in with what minimum voltage the horn requires.

When you have a moment, take these two measurements immediately after each other, without changing anything on the bike/battery/charger:
- Voltage at the fuse, as you did before
- Voltage as measured between the battery + terminal (with the red probe) and the ground on the transmission (black probe). If your bike is set up in the normal way, the + terminal will be right there above the transmission ground.

What you're looking for is the difference between the two measurements. If your battery is 12-13V, but you're only reading 10V at the fuse, you have a significant voltage drop somewhere along the way. (i.e. increased resistance from dirty connectors, dirty grounds, wimpy OEM ground cable, etc., all of which impedes the flow of current from the battery to wherever you want it.)

[mac]

When you have a moment, take these two measurements immediately after each other, without changing anything on the bike/battery/charger:
- Voltage at the fuse, as you did before
- Voltage as measured between the battery + terminal (with the red probe) and the ground on the transmission (black probe). If your bike is set up in the normal way, the + terminal will be right there above the transmission ground.

What you're looking for is the difference between the two measurements. If your battery is 12-13V, but you're only reading 10V at the fuse, you have a significant voltage drop somewhere along the way. (i.e. increased resistance from dirty connectors, dirty grounds, wimpy OEM ground cable, etc., all of which impedes the flow of current from the battery to wherever you want it.)

You're right about corrosion/bad connections impeding the flow of current, but any resistance can only cause a voltage drop if current is flowing through the circuit. To test the voltage drop on the circuit, you need some load.

If we're talking about the fan/horn circuit, and you're not hitting the horn button, and the bike is cold (no fan), there should be no current flowing through the circuit--the circuit is open. You have to complete the circuit with the voltmeter to get a voltage reading, of course, but the volt meter has a very high internal resistance. Therefore, you shouldn't see any voltage drop at the fuse when you're not blowing the horn or running the fan.

Add some load to the circuit (blow the horn or run the fan), and now you can measure the voltage drop under load on the wiring between the fuse and the battery.

[JamesInCA]

If not voltage drop, what do you call it when the voltage at a peripheral point (e.g. the fuse) is lower than the voltage found across the battery terminals?

Is this diminished voltage not due to resistance in the wiring between the positive battery terminal and that peripheral point?  (Setting aside, for the moment, resistance in the bike's ground cable. The measurements are probably better done with one probe attached directly to the negative battery terminal; it just isn't very conveniently located.)

In any case, my point is that if he's reading 10V at the fuse, there's either something wrong with the battery, or something going on in the wiring. If the voltage across the battery terminals is substantially higher than 10V, it's in the wiring.

[Westone]

Add some load to the circuit (blow the horn or run the fan), and now you can measure the voltage drop under load on the wiring between the fuse and the battery.

Well, unfortunately neither of those items work. The horn is broken, and the fan is either broken, or with the cooler weather we are having here is just not getting hot enough to turn on when it is idling in the carport for 10 or 15 minutes.

With the red lead of the tester on the positive terminal of the battery, and the black lead grounded, it reads 13.5 volts.

[johnny]

if it was me... i would pull the tank... from the fan motor follow the wires back to the under tank connector... unplug and use jumpers to apply power to the fan... this way you will know if the fan works...

j o

[JamesInCA]

if it was me... i would pull the tank... from the fan motor follow the wires back to the under tank connector... unplug and use jumpers to apply power to the fan... this way you will know if the fan works...

j o

It sure seems like that's what is next. Along with the same for the horn, and testing the horn relay.

Also, check Johnny's link from earlier: http://www.ibmwr.org/ktech/fan-diagnosis.shtml. Lots of good fan assessment info there.

You can get a quick check of the temperature sensor's reading by checking resistance across pins 10 and 5 of the fuel injection computer connector (on the cable, not on the aluminum box) at ambient temperature, and again after running the bike long enough to warm it up to where the fan should about be coming on. Checking it there doesn't require getting into the relay box. It's a separate sensor from the one that controls the fan on/off, but the two are housed together. Values you should expect are discussed at the link.

[Westone]

Well after all of this, the fan came on while idling after about 25 minutes. And I finally got time to pull the fairing and replaced the horn after finding 12 volts at the leads when the button was pressed. Sorry for all the digression, it seemed something else was wrong. Thanks for the help.