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Motorcycle Repair/Cooling Fan Not Running


I have a 1997 VZ800 Marauder. Excellent Bike! The fan that cools the radiator is not running. What are a couple of quick checks that I can do before taking it to the shop? I would like to have an idea of what is wrong before it goes into the shop, as they are not always up front about things. Thank you for your time.

VZ800 Radiator
VZ800 Radiator  
Hello Shannon,

Most probably the problem is the cooling fan thermo-switch.

There are two sensors/switches on the radiator. The lower one, is the fan's thermo-switch.
Follow the wires coming out of it, to locate the connector (see picture), disconnect it, and using a piece of wire or cable, make a short between the terminals (on the harness side).

At this point, if you turn the main switch on, the fan should start, confirming that the thermo-switch is out of order.

On the other hand, if it doesn't start, the ground on the connector and the power (+12V) at the fan must be checked.
If you think you can perform more advanced measurements and tests and you have a basic multimeter, get back to me and I'll guide you through.

Best Regards,

Motorcycle Repair

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Lazaros Ampatzidis


I can help you on EVERY issue involving POST-1980 Japanese Motorcycles plus KTM and Husaberg. My field of expertise includes Engine, Transmission, Fuel system (carburation & EFI),Electrics and Electronics. Maintenance, repair and tuning. Road and off-road suspension tuning. Please don't ask me about non-Japanese Motorcycle, especially American built on which I have low to zero experience.


I'm a rider and hobbyist since childhood. 25 years motorcycle workshop mechanic.15 years motorcycle racing mechanic. In order of experience high to low:Kawasaki,Suzuki,Honda,Yamaha,KTM,Husaberg.

Hellenic (Greek) Technical School.Internal Combustion Engines Engineer. Automotive Electronics.

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