cooling fan ?

[Dan505]

I've noticed I can't hear my fan turn on in traffic on hot days. No warning light comes on but I always heard the fan in the past. I'm trying to test the fan as in the clymer, at the point to take the plug off the switch. I don't want to snap anything. Should I use a screwdriver or channel lock pliers to pry off the connection. Thanks

[GregFeeler]

I've noticed I can't hear my fan turn on in traffic on hot days. No warning light comes on but I always heard the fan in the past. I'm trying to test the fan as in the clymer, at the point to take the plug off the switch. I don't want to snap anything. Should I use a screwdriver or channel lock pliers to pry off the connection. Thanks

If it's the connection I'm thinking of, they are rectangular and have a wire snap ring that holds them on. Look at the short sides of the plug and you should see the wire in a channel and then see a tab the ring is locked to. There is an open side to the snap ring on one of the long sides of the connector, and sometimes you can get you finger in there and press against first one and then the other end of the snap ring and work it loose. Other times you might need a very small screwdriver or hook to catch it. The trick is to get both sides loose at a time. :banghead DON'T pry it off or you'll break something.

[Dan505]

Yes the book also says to remove a clip, I can't feel or see a clip in there.

[GregFeeler]

Yes the book also says to remove a clip, I can't feel or see a clip in there.

Which connector are you trying to remove - located where?

[Dan505]

The connector is at the cooling fan switch by the coolant pipe in front of air box on an 88K100 !40K miles

[GregFeeler]

The connector is at the cooling fan switch by the coolant pipe in front of air box on an 88K100 !40K miles

That's the one I thought you were after, and it does have the wire clip. :nod

[BuddingGeezer]

I've noticed I can't hear my fan turn on in traffic on hot days. No warning light comes on but I always heard the fan in the past. I'm trying to test the fan as in the clymer, at the point to take the plug off the switch. I don't want to snap anything. Should I use a screwdriver or channel lock pliers to pry off the connection. Thanks

You did not say what bike you have.

If you have the L Jetronic fuel injection system you will find the Clymer manual has made a mistake. Clymer says to remove the temp probe connection, ground the connector, turn on the ignition and if good the fan will run. Clymer is WRONG. The fan gets its power from the fuel injection relay fuse # 7. You must also press the starter button to energize the fuel injection. If the fan and fan switch is good then the fan will run. It will not run just grounding and turning on the ignition. If you have the Motronic ?????????????/ I have repaired 3 L Jetronic fans, no Motronic.

If your temp probe is good and the fan and temp warning light will not come on, the fan switch is bad.
Most of the time the plastic brush holders are melted in the motor.

I have given detailed fan diagnostic instructions on this forum multiple times. You can find the posts with a search.

Ralph Sims

[Dan505]

got the connecter off and jumped it with ing. on fan did not run. Is their an easy way to get 12V to the fan motor or dose the radiator have to come out.

[GregFeeler]

got the connecter off and jumped it with ing. on fan did not run. Is their an easy way to get 12V to the fan motor or dose the radiator have to come out.

Did you also hit the starter as per Ralph's post?

You might try reaching up behind the fan with a long screwdriver (be careful) to see if the fan blade will move when you gently push on it. K-bike fans are prone to getting dirty and binding up because they don't run very often. Many times you can remove the fan, dissemble and clean it really well to get it working again.

[Dan505]

I have an 88K100RS the fan does not seem to be binding when spinning by hand. I don't know if I have a K or J tronic fuel system, but I did try jumping the connecter & pushing the starter button this time & fan or warning light did not come on.

[Dan505]

Got the radiator out (bit of a pain in butt 1st time) jumpd the fan and it turned on. What would you guys suggest I do next.

[BuddingGeezer]

Got the radiator out (bit of a pain in butt 1st time) jumpd the fan and it turned on. What would you guys suggest I do next.

The 88 model has the L Jetronic. Since your fan works I bet the fan switch is bad, located in the relay box under the tank. For some reason BMW did not have the high temp warning light light with the ignition on like the low oil pressure light does. If you have gotten the bike hot and the warning light did not light and the fan did not run after grounding the temp probe and hitting the starter button it is most likely the switch.

However take a resistance reading on the probe cold then apply heat (hair dryer will work) and see that the resistance lowers. If it does not, temp probe is bad. Usually when the temp probe is bad the bike will run rich when warm.

Ralph Sims

[Dan505]

thanks I'l give that a try. I read another web page that suggested disconnecting the fan switch & jumping some wires at the plug. I'l also give that a try & see what happens.

[Dan505]

Kudos to Jeff Dunkle. Thanks to his fan test page on IBMW, I know my temp light works, fan works, & I don't have a wiring problem. I will do the temp. probe test when I get a chance, if it checks out ok I'll replace the switch. I'll post the end result.

[BuddingGeezer]

Kudos to Jeff Dunkle. Thanks to his fan test page on IBMW, I know my temp light works, fan works, & I don't have a wiring problem. I will do the temp. probe test when I get a chance, if it checks out ok I'll replace the switch. I'll post the end result.

I bet it's the switch. Around $60.

Ralph Sims