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Discussion Starter #1
Hi guys. Got a new speedometer for the bike ('88 Sportster) and its got the sets of wires for N, oil, turn signals, and beams, which i have the old wire sets to connect on to. However, the new one has a 5th set of wires for the backlight. Don't know where the stock speedometer got the backlight power from.

Now I'm not very good with electrical stuff, but obviously the backlight has to be constantly on, so it can't be hooked in with any of the other sets. But with wires that small (18 gauge or smaller i think) I don't think I want to try and tie them into the headlight, do I?

Much obliged for any help.
 

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The back light would get constant B+ when the ignition is on. Orange is B+ and black is ground. Orange with a white stripe can also be B+. Test the wires with a test light or multimeter to see that they're hot with the ignition on and dead with it off.
 

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Discussion Starter #3
When you say "The back light would get constant B+ when the ignition is on," do you mean if it was hooked into the headlight? If so I know the headlight is always on, but I didn't know if there would be an issue with amperage flow through the smaller backlight wires from the headlight wires.
 

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The headlight has two (low, high) so that's not the place to hook it. However, most of the headlights have a hot wire in the harness, use that. Or any wire that gets battery when the switch i on. The back light doesn't draw much current, so can be hooked up anywhere.
 

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Correct, the yellow and white headlight wires B+ alternates depending which beam is on. Any orange or orange/white wire has B+ with the ignition on.
What color wires are in the connector that plugged into your old speedo ??? One of those wires had to be for the old speedo back light.
 
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