No lights on my 1974 TC100, workshop manual available?

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KDRK1
Still in the Driveway
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Joined: Tue Aug 11, 2020 4:15 pm
Country: United States
Suzuki 2-Strokes: 1974 TC100

No lights on my 1974 TC100, workshop manual available?

Post by KDRK1 »

New member here. Reliving my youth as I just Just bought a nice 1974 TC100 that I had as a kid. It fires right up but I'm trying to get all the lights working. I have nothing at any of the bulbs and I'm looking for advice on how to test the Lighting coils to see if thats the issue. I'm know electrical genius but thinking its either the coils or the handlebar switch. Bike has only 1200 miles on it. Also cant find a service manual online for this bike, any thoughts on where I can find one? Thanks everyone.
karl pa
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Suzuki 2-Strokes: GT
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Re: No lights on my 1974 TC100, workshop manual available?

Post by karl pa »

Welcome
I think a TC100 has magneto ignition, magneto ignition wiring is totally separated from lighting wiring,so it can run fine but not have lights.
Do you have a good charged battery installed? first I would check fuse is good and making connection,the fuse holder have been known to loose connection,then I would remove headlight, (I am assuming that is where all the wiring plugs together to all switches)check you have 6 volt on red wire from fuse to ignition switch(I am also assuming it is a 6 volt system) then check you have 6 volt on orange wire coming from ignition switch with key turned on. This should get power to neutral light and brake light from battery.
I think the headlight is fed AC power straight from lighting coil through headlight switch, check if you have power on the yellow/white wire going to headlight switch, this should show if lighting coil is putting out.Engine needs to be running to check this.
Last edited by karl pa on Tue Aug 11, 2020 6:44 pm, edited 2 times in total.
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jabcb
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Suzuki 2-Strokes: 69 T350 thru 75 GT750
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Re: No lights on my 1974 TC100, workshop manual available?

Post by jabcb »

Welcome to the forum.

Everyone wants to see a pic of your bike. You can’t post pics here. Post the pic on a photo sharing site like Flickr.com & provide an image link here.


Online parts manual is here: https://www.partzilla.com/catalog/suzuk ... azer-tc100

A reprinted Suzuki shop manual & Haynes Chilton manual are available on eBay:
https://www.ebay.com/itm/SUZUKI-Worksho ... 3057072413
https://www.ebay.com/itm/SUZUKI-SHOP-MA ... 1213411781" onclick="window.open(this.href);return false;

A Google image search for “suzuki tc100 wiring diagram” provides some wiring diagrams. Don’t know if any apply to your bike.

Does your bike have a battery? Is it good & charged up?

Many TS/TC models have a mixed AC/DC wiring system, where some components use AC & others use DC.
The DC powered components should work without the motor running.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 project & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
KDRK1
Still in the Driveway
Posts: 2
Joined: Tue Aug 11, 2020 4:15 pm
Country: United States
Suzuki 2-Strokes: 1974 TC100

Re: No lights on my 1974 TC100, workshop manual available?

Post by KDRK1 »

Thank you for the help. I conducted a bunch of tests and low and behold: brand new battery kept discharging without the key in the ignition overnight. Turned out the rectifier was cracked and quite warm doing nothing. I replaced the rectifier and all is good. Lights work as they should and battery remains charged. Little did I know these rectifiers can actually go bad and completely discharge the battery and allow much too high a voltage to these components. $20 part and 4 hrs of testing! Isn’t that the way it always goes!!!
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