sent this, which corresponds to Erdeniz Umman's wiring diagram:
GL1500 ECM Wiring (1992 - 2000)
1. Yellow/red (Connects to an ignition coil)
2. Yellow/blue (Connects to an ignition coil)
3. Yellow/white (Connects to an ignition coil)
4. Black/white (Voltage from the Kill switch) Note: Also goes to all three ignition coils.
5. Green/black (Connects to the “intake air temperature sensor” and the “engine coolant
temperature sensor”) Ground wire...!
6. Green/white (Ground from the side stand switch)
7. White/blue (Connects to the ignition pulse generator) <<--
8..White/yellow (Connects to the ignition pulse generator) <<--
9. Pink/white (Connects to the engine coolant temperature sensor) Signal wire....!
10. Green/orange (Signal from the gear position sensor, 5th "OD” gear)
11. Light green/red (Signal from the gear position sensor, neutral position)
12. White/red (Signal from the gear position sensor, 3rd gear)
13. Red/white (Signal from the gear position sensor, 4th gear)
14. Green (Ground from the frame) <<--
15. Black/yellow (Signal from the gear position sensor, 2nd gear)
16. Red/white (Connects to the Carb air jet 2)
17 Red (Connects to the Carb air jet 3)
18. Gray (Connects to the intake air temperature sensor) Signal wire...!
19. Yellow/blue (Signal to the tachometer)
20. Black/red (Connects to the par solenoid valve)
21. Blue/black (Power “voltage” to the fuel pump)
22. White/black (Connects to the cruise control unit)
What I ended up doing with the information I had at the time, was proceed with the Pulse Generator Check (pic below)
I got open circuit (infinity) between both pulse gen wire pairs:
BLU & WHT/BLU (#7)
YEL & WHT/YEL (#8)
Following that wire leads to approximately where those pulse generators are, behind the front engine cover. My next challenge is getting that off without unnecessarily disconnecting too much stuff.
I was really hoping that simply removing that round, 3-bolt cover would give access to the pulse generators, but there's a disc that looks to have to do with crankshaft or belt timing, so I thought I'd better not loosen that until I find out more...