Fixing Unreadable Instruments at Dusk

Rationale

The light level of the instrument lighting is weak - but the real problem is it is not adjustable. No matter what the light level, there is a period of time at dusk (and dawn) where the ambient skylight reflecting off the instrument bezel exactly matches the light emitted through the instrument numerals - and they disappear.  You can improve the situation by upgrading to 5 watt lights - shortens the unreadable time - but they are still unreadable for some period.

             This mod allows you to vary the light coming through the numerals by providing a switch to shut off the light. Now they have LOTS of contrast as they appear black. Then when it's dark enough, you turn them on - thereby eliminating the unreadable problem. I leave mine off always except at night - so my bulbs should last longer.

Cost

About $5

Time

About 2 hours

Materials

• spdt micro toggle switch from Radio Shack
• 4 ft 18GA wire
• heat shrink tubing
• electrical tape
• solder, flux

Tools

• drill
• phillips screwdriver
• jeweler's phillips screwdriver
• pliers
• wire stripper
• side cutters
• soldering iron
• silicon spray
• 2 ft bell wire
• heat gun (hair dryer)

Process

Because the instruments are mounted in plastic/rubber, they have both hot and ground wires in their looms. We must switch the hot wire to the lights as the tach has other lights, so we can't interrupt ground.  Looking at the wiring diagram, it appears one wire can be found to interrupt the circuit - however, the point where the circuits are joined is buried in the loom and difficult to access. It is easier to replace the source for one, with the source for the other, after running it through a switch.  I chose to mount the switch in the bottom of the speedometer instrument cover. This puts it up on the instrument, and seems more natural.   (Another location could be either plastic gusset in front of the tank.)  This necessitated running two wires through the loom to the speedometer, up to the switch and back. Wherever you put the switch, the circuits are the same. It's a little harder to put it in the instrument than elsewhere, due to fit and stuffing the loom.   Remove the speedometer cover by unscrewing the phillips screw at the bottom, and unscrewing the very small phillips inside the knob, and removing the knob. Slit the loom at the back of the speedometer.  Remove the wires from the loom to the speedometer by cutting them in the headlight, pulling out the loom from the back of the headlight, and pulling the wires through the slit in the loom. Add two wires to the other two, wrapping their ends together with the single strand bell wire, spray the loom inside with silicon, then pull the 4 wires back through the loom with the bell wire. Solder the two new wires to the switch. Drill an appropriate hole for the switch in the cover - being sure it will clear the back of the instrument. You may want to upgrade the light bulbs while you have it apart. Reassemble the instrument.  For all of the following connections - put heat shrink tube in place on the wires before connecting them, make all connections by twisting, test the circuits work as expected before soldering and sealing the connections. Solder connections are absolutely reliable - all others are not.

Feed the free end of the loom back through the back of the headlight. Solder one of the new wires to the brown/white wire you cut before.  Cut the brown/white wire at the plug of the loom to the other instrument and insulate the power side of the broken circuit with elect tape.  Identify the end that goes to the instrument, and strip and twist it to the other new wire (from the speedometer), and the brown/white wire to the speedometer, so you have both brown/white wires to the instruments soldered to the new wire that comes down from the switch. Lastly, reconnect the green ground wire to the speedometer, you cut before.  Button everything back up, and you're done.

That's it - not too hard, and now you'll be able to see your instruments!

All technical mods described here are merely reports of what I've done.  You may attempt to replicate them at your own discretion and risk if you choose.  Horseapple Ranch, LLC and Mark Tobias will in no way be responsible for the results of your attempting to perform these mods on any motorcycle, regardless of the outcome.

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