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1981 GS450 Electrical Issues - Dead Bike

  • Thread starter Thread starter jmaresca
  • Start date Start date
J

jmaresca

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I just picked up a beat down 81 GS450S with the intention of fixing it up. It died on the previous owner. He rode it around for a month and one day it wouldn't start. He tried fixing it and gave up. He screwed up the ignition switch and the rear left turn signal. The gauges aren't in the best shape. He replaced the battery and starting motor to no avail. I tested the battery and got 12.4V from it. I ordered a new ignition and it's in the mail. In the meantime, can I connect the cut wires from the original ignition switch to continue diagnosing? If so, which ones? I'm just trying to get the accessory lights working right now. Any gotchas I could be missing? What is the absolute minimum I need to test and what do I need to do to get the lights working? I'm planning on upgrading the r/r to a SH775 and replace the stator if necessary.

I uploaded a few pics here if they could be helpful.

Now wheres that sweet welcoming party I keep reading about? :)
 
Ok. So I found this awesome color wiring diagram here. I hooked up my red/orange wires and brown/gray wires, which should simulate my ignition on. After testing my red in the headlight with a multimeter, I wasn't getting anything. So I tested all the way back to the fuse. Turns out the previous owner put the fuse in backwards. Now I get 12 volts to my red in my headlight. I'm not sure that the new starter relay the PO put in is the right one. It's shaped a little differently. I know because he gave me the original. The wire diagram is showing a 4th connection, ground, that isn't there. Unless that means ground to the frame through the screws. Still not getting any response from anything though. On this wiring diagram I'm seeing a starter disconnect switch, but I can't quite find it.
 
That relay is fine. It is grounded through the mounting bolts/screws. I like to run a wire from one of the mounting bolts to the frame ground bolt, just to insure a good quality ground.
 
You will need to trace the Green/White stripe wire to verify, but that appears to be the clutch disconnect switch. You have to pull in the clutch for the starter to engage. A popular mod is to remove it from the circuit by connecting the Green/White stripe wires together, bypassing the switch.
 
I saw a pic somewhere where the green/whites connect in the clutch. I went to remove the plate covering it and removed every one but the last one...which I stripped. So now there's that to fix hah.

Assuming the harness is solid, which is a risky assumption, which components if broken would absolutely stop everything on the bike from working? Or is it like a Christmas light set where one broken light will ruin Christmas eve dinner? I think my next step is to remove the tank and check everything, but even then, who knows if the previous owner reconnected everything correctly.
 
The switch is normally on the clutch perch on your handlebars.
 
OK, so I skipped the clutch disconnect switch and wired those wires together. I am able to get a 12.4V all throughout my red wire. When I tested my orange wire to ground, I don't get anything. Wouldn't that be the next logical step? I'm considering picking up a new wiring harness, but I'd really like to rebuild a harness without gauges. Are there any wiring diagrams around for pulling something like that off? If I were to pick up a new harness, what years would work in an 81?
 
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The next step would be to check the ignition switch. There are 4 wires going into it, via a connector, probably in the headlight shell.
Red - 12V
Orange - 12V when switch is ON
If you are getting 12V on the red wire but not on the orange wire, I would investigate the switch.
 
If you could speak with previous owner and ask, "when it quit running- what did bike do?"

for me- rectifyer blew and it cause a heap o trouble electrical.
maybe this might help. not that I am a bike wiz.
 
koolaid_kid said:
The next step would be to check the ignition switch. There are 4 wires going into it, via a connector, probably in the headlight shell.
Red - 12V
Orange - 12V when switch is ON
If you are getting 12V on the red wire but not on the orange wire, I would investigate the switch.
Click to expand...

The PO tried to do exactly that, but he lost a bunch of the internal parts to it. I ordered a new one that should arrive in a couple of days. In the mean time, I'm hooking the red and orange wires together and the gray and brown wires together. That should be what's connected when the ignition is on. I tested orange to ground at the accessory lights and get nothing, so I suspect my orange wire is fried. It runs from the headlight back to the seat, and then forward again. So I'm going to have to cut open the harness to investigate.

I also sprayed de-oxidizer on the connectors because they were in bad shape. I'm considering rebuilding a new harness from scratch. What gauge wire would that take? 16? 18? Anyone know where I can get a combo pack of different colored wires for doing something like this?
 
18-20 gauge was factory. Not sure on the multi-colored wires. NAPA carries lots of colors, and there are not that many on a 450 wiring harness.
What about replacing the orange wire, but outside the harness just for test purposes?
 
koolaid_kid said:
18-20 gauge was factory. Not sure on the multi-colored wires. NAPA carries lots of colors, and there are not that many on a 450 wiring harness.
What about replacing the orange wire, but outside the harness just for test purposes?
Click to expand...

That's what I'm going to do tonight. I would like to rebuild the harness at some point because I don't like all of those connectors. But first I'm going to find what's wrong.
 
Got her up and running! Thanks for the help guys! I did the mod to skip the clutch. I disconnected and de-oxidized every connector. I replaced the fuse. My wiring diagram only shows one black lead running to the battery, but apparently I have two. I'm going to go through all of the necessary steps to get her road worthy, put a few hundred miles on her, then rebuild her.

When I do that, I'll definitely build a harness from scratch. Too many connectors that could go wrong. I'm planning LEDs and getting rid of the gauges. The direct connect from the stator to RR also sounds like a good idea.

Thanks again guys. :D
 
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