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[HVMoto]

I started working on my 2nd 2013 DS and I'm troubleshooting some electrical issues.

Is any part of the low voltage (13.5vdc) wiring (beyond the DCDC converter) connected to the frame?

[staples]

My understanding was that it should be entirely isolated from the frame.

[HVMoto]

Thanks, that's what I thought.

I think I have a fault in the low voltage loop. I've disconnected the battery, removed the MBB, CCU, and DCDC so I don't damage anything. Connected a metered DC power source to mimic the DCDC 13.5 volts out and I get a significant voltage drop. There were lot's of accessories (since removed) on this bike, so there could be several points of fault. I'm digging in.

[NEW2elec]

Mine had a small wire grounded to the frame.  Facing the bike on the right side.  Behind the tank plastics on the front of the bike.

[HVMoto]

Ok, making progress, I have a mileage reading.

I removed all 4 low voltage fuses and plugged a 5a DC power source at the out pins to mimic the DCDC. Voltage at the fuse harness was good. Added fuse 2 (front accy) and voltage measured good. Added fuse 3 - flashers, horn and brake lights worked. Added fuse 4 and koso display comes on, voltage good. Added fuse 1 (HDLT - Front Cluster) and voltage pulls to near zero with everything ceasing to function. 5 amps DC source may not be enough for testing headlight but it's what I had available. Focusing in on the front cluster wiring.

Mine had a small wire grounded to the frame.  Facing the bike on the right side.  Behind the tank plastics on the front of the bike.

I'll look for that, thanks!

[Auriga]

Those wires are for reducing rf emissions, no wiring on non FST bikes is grounded to the frame.

[ESokoloff]

Mine had a small wire grounded to the frame.  Facing the bike on the right side.  Behind the tank plastics on the front of the bike.

Could that be to protect the bearings from current flowing through the balls and pitting?
Steering head & swing arm bearings I believe are protected via dedicated grounding wires attached to those components & the frame.

[HVMoto]

I found the ground wire, it's labeled GND LINK TCLAMP MY13, connects front forks to the frame.

Those wires are for reducing rf emissions, no wiring on non FST bikes is grounded to the frame.

Thanks for confirming. Low voltage beyond DCDC appears isolated and functional (using external source). I've tested 2 DCDC converters, no outgoing voltage, but incoming pack voltage within range (when plugged in). Have not located the 4a fuse to the DCDC, even though I've pulled all the orange loom and electrical tape. Will bench test both converters to confirm function.

Keying on bike has no effect. Plugging in has no effect (other than voltage measured through harness). No voltage at OBD2 so can't yet get logs. Pack voltage within range ~103v. Checking pin voltages on MBB today.

[HVMoto]

Thanks for all the input so far! I moved from low voltage to measuring high voltage and getting unexpected results. Very similar to a post from Feb (that had no apparent resolution).

https://www.electricmotorcycleforum.com/boards/index.php?topic=11623.0

I left the MBB, CCU, and DCDC disconnected and plugged the harness back into the battery. Bike keyed off and using a DMM, I measure 103.8v (pack voltage) at the DCDC + in pin using DCDC - as return. I believe that is normal. Moving my negative lead around I also measure pack voltage at M1, M2, M3, the + or - in (to controller) or the + or - at the Anderson connector. Not expected but possibly normal.

I pulled the Low Power B+ fuse and still get voltage (drops to 102.5v but still present). Not expected.

Plugged the MBB back in and measured near pack voltage at the enable in for DCDC converter. Not expected since bike is still keyed off and there doesn't appear to be anything to keep power from going to the low voltage circuits if enable was always on.

Removed MBB and again pulled harness. Confirmed there is no 4A fuse to either the MBB or the DCDC Converter on the harness. Seems there should be but I get this was a modification after 2013 battery recall.

Pulled cover off the doghouse, no additional fuses tucked inside.

What to check next?