Advice on turn signals

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rasandler

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Sep 11, 2012
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Hello -

After nearly 40 years of wanting one, I have just purchased a 73 Commando 850. The previous owner (the original, btw) had switched out the handlebars but still had the stock ones. Before I took possession, I had the old ones put back. Now, there are some problems with the turn signals. For one thing, switching the lever down is activating the left signals. I'm pretty sure this is backwards. Switching it up does nothing (I have checked the bulbs and they are ok). The shop says that the Lucas switches are famous for being buggy and I should try to clean the contacts with WD-40. So here are my questions:

Is it likely that cleaning the contacts will have any impact or are they blowing smoke?
Am I correct that the sides seem to be reversed?
Could this have happened when the handlebars were changed?
Where would the leads have likely been switched and how can I correct?
Do both sides use the same flasher unit or are there two?
Where is the flasher unit located?
What else am I missing?

Thanks so much for any and all suggestions!
 
Last place to look for faults is the bar switches, so first check the connections under tank and just connect so the toggle signals which ever way ya like them and even can change sides of bars, with some wire re-routing. Main fault is usually the Earth path through the chrome layer on plastic parts wears off around contact inside lens. Next is the stem itself attaching to the head lamp or tail bracket. Some have to run a Earth wire to get em to wink every time. A test lamp helps trace the faults.
 
rasandler said:
Hello -

After nearly 40 years of wanting one, I have just purchased a 73 Commando 850. The previous owner (the original, btw) had switched out the handlebars but still had the stock ones. Before I took possession, I had the old ones put back. Now, there are some problems with the turn signals. For one thing, switching the lever down is activating the left signals. I'm pretty sure this is backwards. Switching it up does nothing (I have checked the bulbs and they are ok). The shop says that the Lucas switches are famous for being buggy and I should try to clean the contacts with WD-40. So here are my questions:

Is it likely that cleaning the contacts will have any impact or are they blowing smoke? Possible contact issue. Could also have some broken solder or a bad connection further down the line.
Am I correct that the sides seem to be reversed? What side of the bars is the switch on? The switches can be swapped. Mine are on the left bar and Left is UP and Right is down.
Could this have happened when the handlebars were changed? Were the switches working properly before the bar change. If so, then more than likely something happened during the change.
Where would the leads have likely been switched and how can I correct? They can be wrong in the switch, in the harness or at the bulbs themselves if someone mixed up the color codes. Get familiar with the wiring diagram. I bought one from http://colorwiringdiagrams.com/ . A nice laminated color diagram. Makes tracing wires easier.
Do both sides use the same flasher unit or are there two? Single flasher unit for both sides.
Where is the flasher unit located? Usually located on the left side above and behind the battery. If one side is flashing the unit should be fine but you can replace it with a $3 unit from the autoparts store.
What else am I missing? You can do some continuity tests from the switch along the light circuits to see if there may be a broken or shorted wire.

Thanks so much for any and all suggestions!
Click to expand...
 
As far as the up -left & down. -right thing there is no one correct way. Even the Norton manual has it printed backward of the way they came. You can switch that around to whatever works for you. Sounds like you don't have a manual so if I was you t I would buy one AND the parts book. You really need both.
 
in my experience it's a crap shoot to try and troubleshoot electrical problems in the middle of the path. Start at one end and work your way to the other checking everything as you go. Unless your norton is OBDII :lol:
 
Thanks guys! all good advice! i can almost see where things come together under the tank. it looks impossible to get at without removing the tank. is that true?
 
rasandler said:
Thanks guys! all good advice! i can almost see where things come together under the tank. it looks impossible to get at without removing the tank. is that true?
Click to expand...

Learn quickly how to remove seat and tank. Necessary to properly troubleshoot electrical. If you have the "10" block of wires in the harness under the tank replace it with some smaller units or different connectors altogether. Lots of issues with those blocks. They tend to fall apart. Get connector kit to redo the electrical that needs it. I always recommend disconnecting every connector on the bike, inspecting it, brass brush cleaning it and then assembling with dielectric grease. It will save you some heartache later on.

Blinker unit (Rectangular) Rectifier is the Black finned thing. Mine disintegrated.
Advice on turn signals


Mondo "10" block
Advice on turn signals
 
ok, taking the seat off is easy. the tank? do i need to disconnect the fuel lines or drain the tank? i guess i really need to get a shop manual. i have the rider's manual but i doubt this stuff is covered there.

again, thanks for the great pics and explanation!
 
Just make sure the petcocks are closed. Then unhook the supply tubes from them. Get yourself a manual from Old Britts, they have good exploded diagrams.
 
Manual below. It covers the 750 and 850 models. 16mb file.

http://britmoto.com/manuals/Manuals/750_man.pdf

Take a look through the sticky on the top of the forum for tech info. Lots of stuff there. And yes you will need a manual. I printed mine out and put it in a large 3 ring binder. The diagrams at OldBritts.com are invaluable.
 
drones76 said:
Manual below. It covers the 750 and 850 models. 16mb file.

http://britmoto.com/manuals/Manuals/750_man.pdf

Take a look through the sticky on the top of the forum for tech info. Lots of stuff there. And yes you will need a manual. I printed mine out and put it in a large 3 ring binder. The diagrams at OldBritts.com are invaluable.
Click to expand...
+1 to that. I downloaded the manual from britmoto onto my ipad and take that out in the garage with me, and can also look at the exploded parts diagrams on oldbritts on there as well
 
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