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Discussion Starter · #1 · (Edited)
I got a pre-owned 2015 duke last year. Couldn't ride much due to covid-lockdowns. But when I started riding it in peak traffic, sometimes the fan didn't kick in at all (at around 8-9 bars when it should be kicking in) and sometimes the fan did kick in. It was such a random issue that whenever I went to KTM svc, the fan worked perfectly, and they'd hand me the bike after a day of testing, saying that there are no issues. So I gave it to a local mechanic friend. He did the testing and found that the wiring harness had weakened due to the previous guy storing it in sun for longer periods of time. Wires were deteriorating. So I changed the wiring harness new 2016 duke's. Still, the issue was there, everything (fan, thermostat, coolant temperature sensor) were fine according to him. We also changed fan relays and coolant temperature sensor just to be sure. The problem is still there.

Although in this trial and error process, I found how the problem exactly comes up. Whenever I'm riding at the 8 or more bars of temperature and the fan is running, if I turn off the bike and turn it on multiple times, (typical scenario at each traffic signals in b2b traffic), the fan won't kick in after few restarts of the bike. The previous owner must have had the same issue and that's why he sold it maybe. Cause the bike is running the improved 2016 shrouded fan.

Even though I know how to replicate the issue, I don't know what is causing it. Any help would be appreciated. I was also looking for SPAL fan in india. But its not available in domestic market. Any good sites to import it?
 

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If the fan works, it probably is a ground issue.
If you have replaced the temp. sensor have you also checked the connector (was an issue on my 200).
The wiring loom won't deteriorate due to sunlight in such a short time, my 200 is from 2012 and has been riding the tropics ever since.

Have you tried the reset procedure for the ECU?

Another thing could be that the bars on your dash are not correct and the actual coolant temperature is well below switch-on while the bars are indicating more.
On none of my 2 Dukes the fan ever runs while riding (over 40 km/h) the wind is sufficient in this situation.
 

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Discussion Starter · #3 ·
If the fan works, it probably is a ground issue.
If you have replaced the temp. sensor have you also checked the connector (was an issue on my 200).
The wiring loom won't deteriorate due to sunlight in such a short time, my 200 is from 2012 and has been riding the tropics ever since.

Have you tried the reset procedure for the ECU?

Another thing could be that the bars on your dash are not correct and the actual coolant temperature is well below switch-on while the bars are indicating more.
On none of my 2 Dukes the fan ever runs while riding (over 40 km/h) the wind is sufficient in this situation.
Since I've replaced the whole wiring harness, I think the connector to temperature sensor must have been replaced right? (since it must be a part of the harness).

About the wiring, the previous owner was in Navy and used to be on ships for 6 months straight. his dad just started the bike occasionally to keep it running. Even the wiring to the speedometer console was disconnecting at certain degree of turn of the handlebar.

I haven't tried the ECU reset procedure since I don't know the 15 minute procedure is applicable to previous gen dukes as well. Also, the bike is at garage right now, My friend is getting the KTM diagnostics tool to reset and update the firmware (if the update is available).

About the temp bars, I'm pretty sure it's accurate since we have changed the temperature sensor. and at times it has even squirted coolant due to overheat. and when the fan doesn't start, bars do start creeping up into overheating section. I've even faced a limp mode in city traffic once.
 
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