Mysterious Cutout

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I was helping a Stelvio owner recently his bike started cutting out and eventually blowing fuse 5
It turned out he had pinched the speed sensor cable while mounting the back wheel.
If you look at the sensor (48) it can short out the 12 Volt supply from the main injection relay to the ECU pin 17 and also the kill switch.
If you look back further you will see it also feeds the secondary injection relay which supplies power to all the essential components.
[You must be registered and logged in to see this link.] Almost identical wiring but fuse 4 in this case
I just thought this might be of interest especially if your speedo starts playing up. The cable is quite exposed, it could really do with a small sub fuse.
I believe this cable plugs in up front somewhere.
The diagram looks complicated but it is really very simple taken one bite at a time.

Holy Crap !

This seems like an epic fail on some electrical engineers part.

Why tie a primary operationally critical part to a secondary bit? Especially fueling.

Sub harness seems more appropriate, a fuse would be a simple and helpful rework.

Now, where to put that fuse? What amperage?

ratso88 wrote:

Holy Crap !

This seems like an epic fail on some electrical engineers part.

Why tie a primary operationally critical part to a secondary bit? Especially fueling.

Sub harness seems more appropriate, a fuse would be a simple and helpful rework.

Now, where to put that fuse? What amperage?

Perhaps on the top side of the 3 pin connector, I'm sure 1 amp would be more than enough, as you say the speedo going out shouldn't be a show stopper.
One thing the Stelvio diagrams show is an Anti Theft Device (Option), not shown on the GRiSO. This interrupts the 12 Volt supply.

Months ago I was chasing a flakey turn signal error and had to remove the black shroud from the dash to get to the connectors. I found several connectors tucked in there. (some were showing slight evidence of corrosion. I cleaned all the connectors and the turn signal error went away.) I seem to remember seeing a connector that came from the speedo cable.(I was surprised because I thought the speed cable went to the ECU.) The dash housing would be a lousy location to put a fuse but I made a note that connector could be a potential trouble spot for the speedo.
Am I remembering that correctly? Maybe mine's a on-off wiring job. Feel free to chime in.

tvboy wrote:

Am I remembering that correctly? Maybe mine's a on-off wiring job. Feel free to chime in.

Chiming in.


No, you a not remembering correctly. The speed sensor is connected to the ECU, not the dash.

Good to hear. Next time I'm back under the black cover I'll trace that cable more carefully.

tvboy wrote:

Good to hear. Next time I'm back under the black cover I'll trace that cable more carefully.

I have a 2007 2 Valve, on mine the molex connector is very close to the RH bottom corner of the battery tucked under the frame rail.

I have a connector there as well. What's weird is when I wiggled the connector by the dash I saw it wiggle back down toward the lower speedo connector by the battery.
I assumed it was the same cable. I was thinking maybe the speedo runs all the way to the dash area then on to the ECU. The schematic doesn't show a second connector in the cable so it is obviously something else. I'm curious now what it is but the bike runs great with no faults so I'll leave it be until next time.

Don't assume anything is connected to anything simply by the colour. A meter or continuity tester will tell a different story. On my Sport the wire from the alternator to one of the big fuses hanging off the battery changes colour somewhere in the loom.

However, remember there is also a couple of multi-pin connectors that travel between the ECU and dash. When my bike was new, I had intermittent L/H blinkers. I found that on of the connectors on the dash did not have the pins inserted correctly. Re-inserting them solved that problem. Other funny things also happen - like when I give the old girl the berries, the L/H blinker comes on - probably an issue in behind the blinker lever - I can't see well, so I have left it alone, until I can't any more.

Remember 'talian 'lectrics are notorious for being poorly done and inconsistent in wire size and good connections. All you can do is repair each bit as you come to it. A classic example is the "startus interruptus" condition - wrong sized wire, too many connections, and a route that does several laps (seemingly) of the bike before it actually used.

Did I tell you about the time when I pressed the horn and lost all lights? Damn horn wire frayed and was touching the oil cooler mounting bolt (oil cooler is on the front on mine).

Open up either of the schematics I linked to and trace the wires from item (48) you will see where they go.
+12 Volts - this is the common wire that will shut the bike down if shorted to chassis
Signal to pin 24 of the ECU a square wave pulse, you can see this with your meter slowly turning the back wheel
Ground -12 Volts for the sensor
Perhaps the wire is running in the same loom from front to rear of bike as the one by the dash
I'm not sure if the Speed signal is used in the ECU but it gets to the dash via CANBus probably as a number not an on/off pulse as it entered the ECU