Charging/Electrical Issues

dustin gary

XS400 New Member
Reaction score
South Dakota
Hey all I recently purchased a 1979 Yamaha XS400 FB that runs but the battery isn't charging with the aftermarket 8 wire rec/reg(shindengen sh236-12) the previous owner wired in. I tested the 5 stator wires for continuity and they all read good but I haven't been able to do a dynamic test for voltage. I'm not sure if the rec/reg should even have 8 wires since all I've found for those is Honda information and most for these bikes look like 7 wire units. Previous owner also replaced/mangled a handful of wires that don't match up with wiring diagrams and there's some plugs that I can't find what they're for. I don't know where else to look on this bike and if I should just replace or fabricate my own harness. Any help with wiring in this rec/reg would be appreciated and identifying what the plugs are for. I also need a gas tank so I'd take advice for that too.


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Welcome to the forum!

I am not sure I am going to be much help here, but at least with the connectors, you usually can ID them by:
1. were they are on the bike.
2. how many pins are in the plug
3. the color of the wires at the plug

Based on your pictures, the one shown in file ...53046.jpg looks like the connector for the auto cancelling unit. The one in ...09073.jpg looks like it might be fore the voltage regulator. And the one in ...32548 looks like it is for the signal flasher relay. However, there are a bunch of abnormal wire colors in those shots and a lot of splices covered with electrical tape that are confusing. Rarely is it better to just start over with building a new harness from scratch, but you need to look at the splices and figure out things using the actual OEM wire color codes and the wiring diagram.
Thanks boss, I just decided to take the harness off and start labeling and testing wires. Still don't have a clue how the rec/reg is supposed to wire in.