strange dash issue

sand300

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hi all I'm a new member with a rc390. love the bike (handling reminds me of my old 2 stroke!) but I'm having a few electrical gremlins.

the bike was stored for a week. went to go use it and the speedo wouldn't light up. it's like the kill switch is in the off position. high beam flash and indicator function works but other than that it's dead.

thinking it would be the speedo itself failed I borrowed a friends bike to try his. sure enough his dash is dead on my bike too. my dash works on his bike though so at least I know that's good.

bike starts and runs fine, fuses are all good and I've checked relays under the front tank and they are fine.

I'm guessing theres a broken wire to run the live feed to light up the speedo. can anyone tell me which wire it is? also does it trace back to the ecu?

any help is much appreciated:)
thanks
 

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sand300

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well I've managed to get hold of the ktm repair manual. wow the loom is bizarre.

it's not clear like a Haynes manual on the schematics. I'm working my way through it but its pot luck finding the damaged wire as it's not clear what wire does what.
 

sand300

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been going through the loom from the dash multiplug.

the continuity checks out on all the wires from the ECU. I've tried another ECU to no avail.

theres a few wires I currently cant check as the I'm not sure where they go. in the manual its called P60 vehicle control unit?

what is this part? what does it do? I cant seem to locate it.

think theres 3 wires from the dash.

theres another wire Pin 1 on the dash multiplug. according to the manual it goes to fuse 2.
theres power at that wire into the fuse but no continuity to the dash plug.

the manual states fuse 2 is start auxiliary relay. I'm not sure that's really related to what is going on.

I'm tempted to run a wire from fuse 2 to pin 1 however I'm very worried about damaging the speedo putting too many volts through it.

any thoughts?
 

Fasteddy

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pin 1, white wire should have B+ on it at the combo instrument plug, I would not jumper power to it but trace / check its path with a meter starting at fuse 2, It goes through the plug on the right side by the voltage regulator so that would be first place to check.
 

sand300

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thanks fasteddy, yeah the explanation of the wiring diagrams was invaluable and has certainly helped me get this far.

according to ktms wiring diagram the white wire goes directly to the multiplug on the right side (no power on pin 1 or continuity)

I'll trace the wire back to fuse 2 but according to the loom diagram theres nothing else along the way.
 

sand300

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and we're back in business.

thanks fasteddy for assistance:)


you wouldn't believe how many bits the bike is currently in now lol

I'm pretty reasonable at wiring but getting used to the ktm wiring diagram, working out the mistakes In the loom colours compared to the manual (theres quite a few where the pins match but colours are wrong compared to the manual) made this a bloody challenge.

so for anyone who needs this help in future PIN 1 white wire is the little bugger that fires the dash into life.
 

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Fasteddy

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Ah, high I2R strikes again! the corroded / damaged wire was providing high resistance and low current to the combo instrument...
Was the harness being pinched or crushed? what caused damage?
 

sand300

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I didnt know it was a common problem. I did search.... a lot lol

I'm not sure. I'm going to guess it's been pinched behind the fairing panels as that part of the loom wasnt clipped or ty-wrapped to anything. it was entirely chopped in half.
rest of the wires are undamaged strangely enough.

I'm just happy it's fixed. it almost broke me :)
 
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