T20 wiring issues

doug rooney · Post by **doug rooney** » Mon Jun 01, 2009 4:14 am

Bike is running now. Someone did some odd things with this wiring before I got it. Brake light only works when lights are off. Turn the switch to headlight position and bike kills.
Inside the light housing there are 2 red wires coming out of the switch, one has a fabric sheath on it with dual female connector. Connected everything as per wire color and was left with that wire and 2 gray males that come from the instrument lights. Plugged those into the red sheathed dual as that was all that was left. (Concern about the color difference however)
Back near the battery area, have a red and black/white stripe wires coming out of the rectifier. Diagram does not show this black.white wire. They go to some kind of connector that is all taped up and all that comes out the other side is the red that goes to the battery positve??? Any thoughts?? Thanks

H2RICK · Post by **H2RICK** » Mon Jun 01, 2009 6:34 pm

The black/white out of the rectifier is probably a ground.....or maybe the input from the alternator stator....depending on if the rectifier is grounded
through its body or not.
A quick check with your VOM set on the diode checking position will show you which way to wire the rectifier.
Those old girls use a very simple charging system with a zener diode to bleed off the excess voltage to ground....just like the 60's and 70's Brit bikes do.

I can't help with the key wiring because I don't have any info on those older bikes....

.....but check the key positions for continuity with your VOM.....with the battery disconnected, of course.

If you have (or can get) a wiring diagram, the key switch continuity pattern is always shown in that diagram so you can check the diagram against what your VOM is telling you.

Odin · Post by **Odin** » Mon Jun 01, 2009 8:55 pm

You put the gray ones in the right spot, why yours is sheathed in red is beyond me all three of mine have the same connections as you described except the sheathing is gray as well.
as for the rectifier connections if you are saying one wire is black with white and another wire is red then those wires connect to the battery, the black and white to the ground and the red to the positive
maybe this will help

tz375 · Post by **tz375** » Mon Jun 01, 2009 10:48 pm

Doug, which switch are you describing the two red wires from?

I'm not familiar with your bike, but the kill switch usually has orange in from the main switch and orange out to the ignition system.

The instrument lights are usually connected to power out of the headlight switch. The tail light is usually connected to the same output.

Orange is usually switched 12v on old Suzukis.

In the wiring diagram that Odin posted it looks like the main switch has 4 positions - off - run - (run +lights) - park

In the run with lights position it looks like there's 12v going to the Headlight, tail, ignition and horn. and it looks like it may also connect in another set of generator coils too. Try matching your wiring to the diagram first and see what looks wrong.

doug rooney · Post by **doug rooney** » Tue Jun 02, 2009 6:46 am

Thanks guys. I'll get er figured out with this info. The sheath IS gray but the wire underneath is red in the headlight Odin. I have the same diagram as you posted so just got to follow all the lines.
TZ, was speaking of the 2 reds in the headlight but being that one has GRAY sheath, it makes sense that it is hooked up correctly. I know there are 2 reds out of the rectifier, one for the bat and one for the fuse. That black/white stripe wire needs to go somewhere and will putz with it.

Post by **Suzsmokeyallan** » Tue Jun 02, 2009 8:56 am

FWIW On the T500 the black and white tracer was a part of the ground circuit in the battery section of the harness. The T20 hopefully will follow the same pattern...

Odin · Post by **Odin** » Tue Jun 02, 2009 3:48 pm

Its the same on the T20 Allan, I thought I was clear on that, oh well.

Post by **Suzsmokeyallan** » Tue Jun 02, 2009 4:02 pm

Oh yes Keith, you did say that and i said it too now i read back your post,, oh well a senior moment on my part.

doug rooney · Post by **doug rooney** » Tue Jun 02, 2009 5:41 pm

I hooked it to the rectifier ground but made no difference. Found out it DEFINITELY doesn't go to the pos side. Do you suppose it should go to the neg bat terminal???
I'm no electricain as you can see.

Post by **Suzsmokeyallan** » Tue Jun 02, 2009 8:37 pm

Oh i hope you didnt blow up the diodes in the rectifier now. Send a pic of what youre trying to do with the wires there to make the visual aspect of it easy for us all to see.

doug rooney · Post by **doug rooney** » Wed Jun 03, 2009 7:37 am

bear with me folks. I'm dumb at posting pics too. Still trying.

http://s7.photobucket.com/albums/y289/a ... nt=091.jpg

OK, can't seem to bring the pic to the site but at least have a hot link now. The bike ran after I fooled with touching the black/white wire to the pos so doesn't that mean the rectifier is ok? So, from that connector where the red goes to the bat, where should the black/white go? Had it hooked to the frame ground nut at the rectifier but didn't help.

Post by **Suzsmokeyallan** » Wed Jun 03, 2009 8:08 am

Ok,,, so the red wire comes out the + battery terminal and goes to the red of the rectifier and then from the same red wire on the rectifier to the red wire in the main harness.
The black and white from the - battery ground terminal goes to the black and white in the main harness.
The pics not look too good in this regard, wheres the negative wire from the battery???
You can still buy the little sub harness that goes from the battery that will plug into the other half of that black two pin plug you have there on the bike.

Heres one on ebay with free shipping and a BIN:

http://cgi.ebay.com/ebaymotors/Suzuki-T ... ccessories

doug rooney · Post by **doug rooney** » Wed Jun 03, 2009 10:26 am

I have the red main harness wire going to the fuse line and onto the rectifier. I have nothing going to the neg battery. Only the ground strap to the frame. There is no blk/white wire in the main harness. Only that short piece coming from the recti. There is a blk/white on the new brake lt switch and saw nowhere for that to go so it is hooked to the tail light solid white???

tz375 · Post by **tz375** » Wed Jun 03, 2009 1:35 pm

Doug,

Allan is right that black/white is the ground lead from any light etc. In most cases, Suzuki did not tie the battery directly to that ground lead. What they tend to do is to ground teh negative terminal of the battery to the frame and then attach all the gounds to the loom and then take one black/white wire and ground it somewhere. For example on a GT750 the ground is attached under the tank to a screw on a small bracket, so they rely on a good contact through the frame. There's a ground strap from the rubber mounted (GT750) motor to the frame. Then they had a ground lead from the rectifier and from teh regulator which connected into the loom.

The long and short of it is that ALL the grounds need really clean connections including the headlamp shell into the loom etc.

The rear lamp switch usually has power in one side (orange) and white out to the lamp. If it's a generic switch, connect one side to power and the other to White.

Post by **Suzsmokeyallan** » Wed Jun 03, 2009 2:51 pm

The black and white wire on the short piece coming from the rectifier goes to the negative terminal on the battery.
There should also be an earth wire on the main harness that grounds to the frame as well. Usually found under the tank area or by the airbox.
As Richard says,the brake lamp has its own two wires by the switch, an orange and a white, when these are bridged together the brake lamp should illuminate.