Please help gs850 1979

[Guest]

Hello, I've got a 79 gs850 problem #1 no turn signals, problems #2 no brake light. okay so I turn the key and I've got my instrument cluster lights oil, neutral , and headlight high beam. The headlight and taillight work. And the horn and push start works. But no turn signals, on the back of the frame there's a white wire, its always constant power and I'm guessing license plate light? Anyway any help would be appreciated thanks , Jeff
Additional info the fuse box has 3 fuses, the 4th slot has been ripped out. Then about where the gas tank tail is on the frame, the wiring harness has 2 female plugs " factory" a yellow/black I think and a black/white. Then beind the headlight is the largest headache of all there a green and black female for turn signals., and a double black ground with one female slot empty. I know it's alot to decipher without pictures but any help.or tips would help I'll have photos tomorrow

[Brendan W]

have a look at this

http://members.dslextreme.com/users/bikecliff/images/1979_GS850GN_wiring.gif

[fastbysuzuki]

The two wires at the rear of the fuel tank look like the feed/ return to the fuel tank sender. The only white wire I see on diagram going to the rear is to the tail/stop lamp. If someone has ripped out a fuse and presumably the connections you need to find out what that fuse was feeding. The diagram is fairly easy to follow so it's multimeter time to test where the problem is.

[Nessism]

The 1979 850 had a problematic turn signal control unit (TSCU) which often failed. Suzuki must have recognized the problem because the system was totally redesigned for 1980. There is no easy way to upgrade to the new system so that leaves trying to find a good TSCU or converting to a fully manual system instead (there are instructions in the archives here on the conversion.)

Regarding the brake light, be sure to differentiate whether you have a brake light issue period or just a problem with one of the switches. The front brake light switch in particular is fiddly and should be occasionally cleaned and greased. It's adjustable too by loosening the two screws that attach the switch to the brake lever pivot and sliding the switch housing. Lots of info on the front switch in the archives too, with warnings about small parts so take heed in this regard before you wind up losing the small pieces.

Good luck

[Jeffygonewilld]

Thank you I have a 78 gs550 ive taken the tscu off and placed it on my 850 still nothing. The 550 lights work fine by the way. And I've tried to switch out the handlebar control switch still nothing. Im going out in few hrs to take photos because I'm terribly lost

[Jeffygonewilld]

Video of wiring problem

Please go to this link, it's a video explaining my current problems I'm.okay at wiring but someone has gutted this harness and I cannot figure anything out please lend me your wisdom thanks, jeff

https://youtu.be/8GIhnKNFJ84

[Nessism]

Thank you I have a 78 gs550 ive taken the tscu off and placed it on my 850 still nothing. The 550 lights work fine by the way. And I've tried to switch out the handlebar control switch still nothing. Im going out in few hrs to take photos because I'm terribly lost

The 550 does not use a TSCU. I suspect you swapped the signal relay which is a totally different part.

[Jeffygonewilld]

The 550 does not use a TSCU. I suspect you swapped the signal relay which is a totally different part.

Well that explains alot, thank you for letting me know that. So should I put a meter on the old make sure I'm getting power? How would I even check that. I honestly have no clue where to start

[Nessism]

The factory service manual has some info about the turn signal circuit. http://members.dslextreme.com/users/bikecliff/

[Jeffygonewilld]

Would I be able to buy a 80's tscu and it work ? There's no conversion or bypass ?

[Nessism]

Would I be able to buy a 80's tscu and it work ? There's no conversion or bypass ?

The later TSCU won't fit on the earlier bikes. There is a mod to convert your signals to full manual though. Think you may need new hand controls. Can't remember. There is info in the archives which you should be able to dig up using the search function.

[Brendan W]

That thing in your hand at 4:45 in the video is a voltage rectifier/regulator.
I took the tscu off and fitted a two prong flasher unit and ditched the dark third wire to the tscu and that was it.

[Nessism]

That thing in your hand at 4:45 in the video is a voltage rectifier/regulator.
I took the tscu off and fitted a two prong flasher unit and ditched the dark third wire to the tscu and that was it.

With the 2nd gen TSCU you can remove it completely and the signals will flash normally, only they won't turn off automatically. It's a far more fault tolerant design. On bikes with the 1st gen system you won't get any flashing at all on one side or the other when the TSCU fails. I 'm not an expert on how the system works but I've read a number of posts here in older threads on the subject.

[Brendan W]

With the 2nd gen TSCU you can remove it completely and the signals will flash normally, only they won't turn off automatically. It's a far more fault tolerant design. On bikes with the 1st gen system you won't get any flashing at all on one side or the other when the TSCU fails. I 'm not an expert on how the system works but I've read a number of posts here in older threads on the subject.

Now that you mention it. I had completely forgotten this complication.

[Jeffygonewilld]

what kind of flasher unit ? like the 12v 2 prong cube ? could I use the one off my 550 parts bike? also what wires did you hook into the 2 prong flasher? and ditched the third wire? just cut it off? or taped it up? sorry for all the questions just don't want to mess anything up oh also does the tscu have 4 wires and under the battery box. I have red, red/white, white/blue and yellow coming out of it unless this is the wrong module.