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Electrical/Tail-Brake Light Question

4K views 63 replies 10 participants last post by  Sidecar Bob 
#1 · (Edited)
Hello. I'm trying to hook up all new lights and turn signals. After taking off the front fairing, I have a birds nest so I decided to start at the back. I mounted the new brake light and tail lights and I believe I have them connect correctly.

However, my problem is the brake light is always on (as opposed to the tail light setting) and when I try the turn signals they do not blink (they just burn solid).

I checked all fuses. Electrical is not my strong point. Do you think a bad relay would cause this? Or do I need the headlight and front turn signal installed for everything to work correctly? Or something else?

[edit] These are NOT LED lights.

Thanks for the help!
D
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#34 ·
Your link is incomplete. It doesn't include the item number so it opens a search page.

Almost all of the master cylinders sold online these days are made in China (with the exception of brand name ones made in Europe). Among the ones sold on eBay some are garbage and some are good. Some are sold by US sellers who import quantities of the exact same ones that the Chinese sellers have and re-sell them at much higher prices with much higher shipping rates but at least you should get it sooner. Some of the ones sold at higher prices by "US sellers" are drop shipped from the same factory in China so you will wait just as long as if you bought from a Chinese seller for a lower price. Whoever you buy from, unless you know someone who has bought one from that seller before there is no way to know whether it is good or crap until you buy one and try it. The one I linked is good, or at least was when I bought them for my bikes a couple of years ago on Murray's recommendation. Before I bought those I bought some that were a couple of $ less. I installed one and in a year it had problems and not long after that the boot that protects the piston fell apart. Then I listened to Murray and bought the ones he said and they have been good so far.
 
#36 ·
The one I linked is good, or at least was when I bought them for my bikes a couple of years ago on Murray's recommendation. Before I bought those I bought some that were a couple of $ less. I installed one and in a year it had problems and not long after that the boot that protects the piston fell apart. Then I listened to Murray and bought the ones he said and they have been good so far.
Cool. I was concerned about it coming from overseas...taking forever to get here, not receiving the product, etc. Was this the same seller that you purchased from?


I meant to mention: There are 4 factors that determine whether a master cylinder is suitable for use on a specific bike:
1) Piston size (you need the correct ratio of master cylinder & caliper piston areas to provide the correct amount of lever movement for the amount of force applied to the disc.
2) Handlebar diameter (your bike came with 7/8" / 22mm handlebars).
3) The angle the reservoir sits relative to the handlebar should be as close to level as possible.
4) Appearance (most important if you are doing a full restoration or a full custom).
Thanks for all the info! I was not aware of the piston size to caliper ratio. Unless I've missed it, I haven't seen this info published by the sellers. I guess it's one of those things you have to just take a chance it's correct?
 
#35 ·
I meant to mention: There are 4 factors that determine whether a master cylinder is suitable for use on a specific bike:
1) Piston size (you need the correct ratio of master cylinder & caliper piston areas to provide the correct amount of lever movement for the amount of force applied to the disc.
2) Handlebar diameter (your bike came with 7/8" / 22mm handlebars).
3) The angle the reservoir sits relative to the handlebar should be as close to level as possible.
4) Appearance (most important if you are doing a full restoration or a full custom).
 
#37 ·
Some mention it but most do not. You need a bigger master cylinder piston for 2 calipers than for one (most 2 piston calipers have smaller pistons so the total area is about the same as the single larger piston). If you use a master cylinder made for 2 calipers with a single caliper the lever movement will be reduced. If you use a master made for one caliper with two the lever movement will be greater and in some cases the lever could touch the handlegrip before the brake is locked.
 
#39 ·
Those could be OK and at least they claim to have a warranty (although I would make sure I had it in writing with the product). But you will notice that they say "assembled in USA" not "made in USA" which probably means that they are the same as the Chinese ones. The price is a lot higher but at least you would be fairly sure of getting it sooner.

What do you think, Murray?
 
#40 ·
Yeah, I saw the "Assembled" part. Unfortunately I have experience dealing with bad sellers (and buyers) in the past and I feel more comfortable dealing with someone in the US. For example, if the guy doesn't deliver the product, or it's faulty, or gets lost in the mail, or whatever, I think I have more recourse dealing with a US entity than someone overseas. Thinking back to my last bad experience, it's probably easier suing/having papers served on a guy in the US than a guy in Hong Kong. :)
 
#41 ·
Update: I roughly installed the front turn signals and, as advised, now my rear turn signals blink. Yeehaw. However, as previously mentioned, the front turn signals I purchased are only 2-wire single filament. I haven't done any investigating yet but I'm wondering if it's possible to convert a 2-wire turn signal to a 3-wire signal? It would be cool if I could simply switch the single filament bulb to a dual filament and then solder a wire up somewhere.

Regarding the rear brake light/master cylinder issue, I got a new master cylinder ordered and hope to get it something this week. Will advise.

D
 
#43 ·
That might work if you had LED signals. Yours have bulbs so...

As for putting 2 filament bulbs in lights designed for 1 filament bulbs, I did that once. When you're poor you do a lot of stuff like that to try to save a buck or 2. I had to replace the sockets and drill out the holes in the posts big enough to let me stuff the new sockets' wires through them. It wasn't complicated but it was more trouble than it was worth..... These days I would probably add a set of little LED running lights instead.... Come to think of it, that's what I did.....
 
#45 ·
The reason why I'm investigating this is because I want the front turn signals to match the rear turn signals...but they don't make the same design signals with 3 wires. I'd have to purchase different front signals or replace all 4 signals with a matching design.

D
 
#49 ·
If you were to use LED bulb replacements there wouldn't be enough current to make the flasher work so you would have to replace that too.

Those sockets are a little expensive for what they are but if they will fit in place of the ones in that are in the signals now and the holes in the shafts of the signals are big enough for the wires on the sockets to pass through they might be able to be made to work. As I said before, I did that once, but knew better the next time.

I can confirm that USDOT & Transport Canada regulations (which are harmonized - one of the few sensible things either of our governments do) do not allow amber running lights on the rear but I cannot confirm whether they actually require running lights on the front other than the headlight. The CX500 had running lights in the front signals from the start of production in '78 and that the GL1000 had them as early as '75 but Suzuki was building bikes without them until at least '87 & probably later.

At any rate, whether required or not, running lights are a good idea.

I'm sure you could hide a pair of these in some unobtrusive place where they wouldn't be noticed until they light up
2 PCS 3W LED Working Assist Light Round Daytime Running Lights Inspection Lamp | eBay

These are really turn signals but they could be used as running lights and they are only 2.5" long
2x 16 LED Motorcycle Brake Stop Running Lamps Turn Signals Indicators Lights | eBay

And there are lots of similar but different items available too....
 
#51 ·
Guys,

With the key turned on, I used a multi-meter between the front running light wires and the ground and I don't get any volts. The turn signal wire looks good..just can't get anything from the running light wire. I would think I should see 12 volts between the green ground and the orange/white or green ground and blue/white anytime the key is turned on?

Thanks,
D
 
#52 ·
The only time you shouldn't have voltage between the orange/white and green or between the light blue/white and ground is when the corresponding turn signal is switched on.

Is the main fuse OK? How about the one for the running lights, tail light & instrument lights (the one in the box on the handlebars with the brown/white wire)? Is the cable from the left switch assembly plugged in all the way? Is the battery connected?

If all that stuff is OK try measuring directly across the battery to confirm that the meter is set correctly, then measure from the battery negative to one of the running light wires and again from the green to the running light wire.
If you don't have voltage between the battery negative and the running light wire you have a problem somewhere between the battery positive and the running light wire.
If you have voltage between battery negative and the running light wire but not between the running light wire and the green wire there is a problem in the ground circuit.
 
#53 ·
Thanks. I had already tried some of what you say below...went back out, tried the rest. Nothing. The bike had a fairing on it when I bought it...I removed it. There is a set of plugs (similar to the flat connectors you see on the handle bar switches) that use to plug into the fairing. I used the multimeter on them and I read 12 volts with the power on and nothing with it off. I'm wondering if those were used for the fairing running lights instead? It also appears someone (could have been whoever installed the fairing) had previously messed around with the wiring. I'll keep looking for the disconnect...however, isn't the running lights just a hot and ground running through the power switch? In other words, why can't I just use the two wires I found and forget about the factory running light wires?

D
 
#54 ·
The original running light wires are supposed to be powered through the turn signal switch so that they are not on while the signal is flashing. That way that the signals are BRIGHT-off-BRIGHT-off which is much easier for other drivers to figure out of BRIGHT-DIM-BRIGHT-DIM.

Besides, if the PO messed around with those wires what else did he change and how is it going to come back and bite you later. It is far better to find out why those wires are not live when they should be and figure out what else isn't working now while it is apart in your garage than to have to do it later on by the side of the road at night.

If the fairing was installed properly it should have had a sub-harness that plugged into the bike's original wiring in the same places where the original headlight and turn signals plugged in, usually with a bulkhead connector on the other end that plugged into the fairing. Sometimes if you look at where the wiring to the fairing was connected you can figure out what is going on. At any rate you should remove the sub-harness now that you no longer need it.

Did you check the fuses on the handlebars? Are the brake light and the instrument lights working? I will be surprised if the problem isn't a bad fuse. Glass cartridge fuses can fail without warning after many years of normal vibration. Sometimes they look OK but the link has let go inside the end cap so the only way to tell for sure is to remove the fuse and test it with an ohm meter (you can't always tell by checking voltages and you have to remove them to check for continuity). After almost being stranded once I make it a practice to throw the old ones out and install new ones whenever I get a "new" bike.

When I got my GL500 everything worked but when I looked at the wiring while changing from the Vetter fairing that came with it to the Honda fairing that already had all my stuff in it I discovered that the fuse for that circuit had failed but still looked OK and the PO had cross connected a wire in that circuit to another circuit to make the lights work. That could have lead to everything on both circuits being dead if the other fuse failed, easily avoided if they had pulled the fuses and checked them properly.
 
#55 ·
Yeah, I had the same thoughts...what else is messed up. In light of the info that the running lights turning off while the turn signal is going, I'll keep troubleshooting the wires. I believe you said this before but it just now made sense.

I sold the fairing and the sub wiring harness last year when I took it off. I remember just unplugging the wires, etc....but I still have those two extra wires that I'm not sure what they are for. If OK with you, when I get back home this evening I'd like to take a picture and see what you think.

Regarding the fuses...yes, I replaced all the fuses when I started working on the bike. However, I did go back and recheck them last night to make sure one hadn't blown.

Yes, the brake light and instrument lights work.

I'm going to look at that left hand switch and see if there's something going on there. I'll also check the wiring diagram again and figure out which color wires are running out of the switch and see if there's any issues there.

One thing worth noting is that it is both the left and right running light wires that are acting up and at this time those are the only two wires that appear to be acting up. I'm betting there is something goofy in the left hand switch.

D
 
#56 ·
Pictures are good.

The extra wires could have been to power a stereo or something like that in the fairing but without seeing it the way it was we can only guess. If I was wiring it to power the running lights without the original wires I would have only run 1 extra wire and connected both of them to it. But I have a saying "I have a hard enough time figuring out what I was thinking let alone why someone else did something."

And I have another saying that applies to the likelihood of something going wrong in the switch "35+ years is a long time". What is really surprising is that so few of the switches on these bikes have failed.

When you open the switch housing you are looking for the part of the switch that has the brown/white, orange/white and light blue/white wires (note that the blue/white is power to the high/low beam switch and light blue/white is right running light).
- There should be power on the brown/white wire whenever the key is turned on so check that first. If it is live and the orange/white and light blue/white are not live when the switch is in the centre (off) position the problem is in the switch.
- If the brown/white is not live that is the problem and you need to look at the other end of the cable from the switch assembly to make sure the brown/white is connected properly. According to the schematic I have it should be in one of the multi wire connectors and the corresponding wire on the other half of the connector should be another brown/white. If the brown/white at the connector is live and not the one at the switch the problem is in the wire.
- If the brown/white at the other half of the connector is not live check for voltage at the brown/white at the switch box.

Let me know what you find.
 
#57 ·
Update:

I got the new master cylinder and lever installed. The rear brake light now goes off.

I also figured out my turn signal issues. I gave up on the incandescent lights and got some LED signals. They also were two wire. So to make the front LED wires work as turn signals and running lights, I added a 3rd wire with a diode per instructions I previously posted. I had to also change out the LED flasher. The first LED flasher I got didn't work...the turn signal was barely lit and wouldn't flash. So I went back to Autozone and bought a different LED flasher. The first flasher I bought only had two prongs like the original flasher..it's the one that didn't work. The second flasher had 3 prongs. I added an extra wire and ran it to a ground per instructions I read in another thread. It worked.

The only other electrical thing left is...my Red Oil Light is on all the time. I don't know if I have an actual oil pressure issue or if it's an electrical issue. Guess I'll start with trying to locate wire and see if I find any issues. I also need to read up on how to manually check to see if I have oil pressure. Anyway....

Thanks for all the help...especially thanks to Sidecar Bob!
 
#58 ·
I figured out why the red oil light was on. Turns out it was the stupid module under the seat that lights up the red oil light if the rear brake light is burned out. In my case it wasn't burned out, but I did change it to an LED. Unplugged and removed it. No more red light when running. Good to go.

D
 
#59 ·
Just to rule out one more thing, you might want to test the oil pressure sending unit and ensure it functions as it should with the idiot light. I think there are posts about that either in the forum or the WIKI, or JC's site (motofaction.com)
 
#61 ·
Good to hear you got it sorted out.

You should not have needed to run a wire to ground for the flasher. Unless the harness has been modified there should already be a green wire with the ones for the flasher.
 
#63 ·
As does my 79 Custom.
I would have to add a green wire if I were to switch to a three prong flasher unit.
 
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