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I have a friend that has a 1998 VN750 that is having an issue that I am unfamiliar with and maybe y'all can help.

He says his water coolant fan isn't coming on. He said he had a short in his fuse block and had to swap it out now his fan won't turn on at all and is causing the bike to overheat.

I know there is a possibility that the fan turns on via one of those relays and I told him that may be the issue but I wasn't sure. Can someone shed some light on this and/or point me in the direction where to look. Any info would be great.

Grace and Peace to you!
Richard
 

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I know the fan runs off a blue wire at the JB, but don't recall which plug it's on. One blue wire is for the headlight, so it's the other blue wire. Look up the blue wire mod for the headlight, then check the other plug for the blue fan wire.

The fan wire was loose in the JB plug on mine, had to tighten it up to get the fan back. To find the problem, I grounded the wire for the fan switch, then jiggled the blue wire at the JB plug and the fan kicked on.
 

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I had this issue with my 98..the actual sensor that plugs into the radiator went bad -it broke at the connection - The sensor would cost roughly 145.00 said the dealer - but he also said it can be by passed using a standard toggle switch - I went that route - auto zone 3 bucks- just hard wired the fan to the toggle - placed the toggle close to reach - works beautiful I can flip it on and off whenever I feel the need.
 

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Spockster is correct.

The fan is powered by the blue wire in the 10-pin connector. I think it is pin 5. Pin 5 is powered by pin 4. Pin 4 is always hot, powered from pin 1, from the battery, through the main 30amp fuse. (confused yet?). when the fan switch (lower left corner of the radiator) gets hot enough, it completes the circuit to ground, which triggers the fan relay to complete the pin 5 circuit. when the pin 5 circuit is complete it is also being feed from the main 30amp fuse.

So your friend should start by grounding out the fan switch. If the fan kicks on, then either the fan switch or the connection to the fan switch was bad. Either way, the positive power to the fan and the fan relay are fine. But if you connect the fan switch wire to ground and the fan still doesn't come on, start tracking down the blue wire in the 10-pin connector and the black/yellow wire (also 10-pin connector) to the fan relay. With the fan switch still grounded check to see if there is power on the blue wire at the 10-pin connector. if there is, then you have a short somewhere on that blue wire. if not, your relay is bad. if that is the case, i would follow the black/yellow wire on pin 4 just to make sure it wasnt cut or something and not allowing the circuit to complete. if the wire is cut or something, then maybe your relay is still good. the relay wire being cut is unlikely, but its always good to check before going through all the crap to replace/work-around the relay.

Best of all this can all be done with the bike off. none of this is powered through the ignition, so no need to have it running.


I will also add, this is to the best of my knowledge and I have never claimed to know everything about everything. Just a little about a lot! :wink2:
 

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I had this issue with my 98..the actual sensor that plugs into the radiator went bad -it broke at the connection - The sensor would cost roughly 145.00 said the dealer - but he also said it can be by passed using a standard toggle switch - I went that route - auto zone 3 bucks- just hard wired the fan to the toggle - placed the toggle close to reach - works beautiful I can flip it on and off whenever I feel the need.

I had the same problem. I was shocked to find out those damn little switches cost so much! I did, however, realize that you can buy a used radiator for like 20$ and they normally have the fan switch with them. So, I bought a used radiator on ebay and now I have a working fan switch.
 

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i did similar Drew..i though maybe it be best to have a parts bike..adding up all the components gets frightening to the bank roll...i picked up a bike just for parts hopefull to save some change down the road.
 
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