Join Date: Aug 2009
Location: Silver Spring, Maryland, USA
Model: '99 Gold Wing SE
On your 1988 Wing..................
There are three wires on your tachometer.
1. Green wire = Ground.
2. Black/brown wire = Back Light.
3. Yellow/Blue wire = Signal from the ignition coil (cylinder 1 and 2)
The signal wire can be accessed at a White 6-pin connector on the right side of the bike (just forward from the battery).
You will see the following "vertical row" of 4 connectors:
1) Black 9-pin, 2) Blue 2-pin, 3) Red 4-pin, 4) White 6 pin.
It will be the yellow/white wire at the White 6-pin connector....!!