Topic: !#@% front turn signals only flash sometimes, 1980 cb900custom

[Hondawggie]

It's not the bulbs.  There must be a bad wire?  Or something because I have the wires behind the headlight exposed, I found which wires go to the turn signals and 1 out of 5 times when I unplug/re-plug those wires the turn signals will in fact flash.

But a visual shows the wires to be fine. 

The symptom:
- ignition on, headlight comes on fine, and front turn signals light up for the "running lights" mode
- turn on left turn signal on the handlebar switch:  the left turn signal light goes dark, but I did have it flashing at one point

- now turn the handlebar switch back to center position -- both signals illuminate for "running lights" mode

- put the right signal on via the handlebar switch -- the right turn signal goes dark

- back to center position on the switch, both signal lights are on again

Earlier tonight I had both flashers working fine.  As I went to button up the headlight, I tested them and no more flashing, just the symptoms above.

Could this be:
- a wire gone bad? which wire?
- the flasher unit intermittently going out?
- low battery?

[MoMo]

Are both front and rear going dark?  Make sure the wire terminals at the flasher are clean.  Tap the flasher to see if it starts to flash-should indicate a bad flasher.  Also, I had a similar problem,  switch contacts were dirty-a bit of Deep Creep and frequent turning on and off fixed it.  Larry

[Hondawggie]

Are both front and rear going dark?  Make sure the wire terminals at the flasher are clean.  Tap the flasher to see if it starts to flash-should indicate a bad flasher.  Also, I had a similar problem,  switch contacts were dirty-a bit of Deep Creep and frequent turning on and off fixed it.  Larry

Great tips, thanks.    The rear flashers light up but don't flash -- does that mean anything?  Also, the turn indicators on the dashboard light up.  With those 2 things, is it possible still yet that the switch on the handlebar could cause only the fronts to go dark?   Either way, I'm taking your advice and will pull the handlebar switch apart tomorrow and use contact cleaner on it and on the metal connector ends of the turn signal wires.

I'll also try the flasher tapping idea tomorrow. 

Do you think this could be caused by a wire issue?
In particular, since each signal has its own set of wires, yet could there be a common shared wire that would affect *both* signals the same?

[MoMo]

Another thing, are you sure orange is connected to orange not orange/white? same with the blue and blue/white?  I did not open the switch I just sprayed a bit of cleaner into the opening and flipped the switch a few times.  Larry

[medic09]

Double check and be sure that your battery is fully charged.  On my '78, the turn signals start to flash very slowly or not at all when the battery is low.  When I increase revs so the alternator is putting out more, they pick up a bit.  Easy to check, and silly to miss it.

[Hondawggie]

Double check and be sure that your battery is fully charged.  On my '78, the turn signals start to flash very slowly or not at all when the battery is low.  When I increase revs so the alternator is putting out more, they pick up a bit.  Easy to check, and silly to miss it.

Wowsa that's a biggie.  It could well be the battery.  I charged it up and put it in the bike over a week ago and haven't had the thing running that whole time, meanwhile I've been messing around testing the headlight and turn signals, draining the battery.

I'm going over right now and hook up my motorcycle jump-starter pack to the battery and check the signals.  

And thanks for that tip on the wire colors, photo, good advice. I'm going to use contact cleaner on the wires and switch just to be sure.

I did check the orange/orange-white  pair of wires (that's the left turn signal on my '80 cb900c) and blue/blue-white pair of wires (right turn signal).   I got to know those wires really well, I spent a frustrating 2 hours last night, teased on by a 'working every once in a while' intermittent correct flashing.  To troubleshoot I was swapping the right turnsignal into the left signal's connections and vice versa.  I bet its the battery getting low.

[medic09]

Let us know what you find out.

[Alan F.]

Not sure about the type of signals you've got on that bike but the ones Honda used on the sohc 4's are the same type as my 81 CM400 has... what I'm getting at is remove the lens and look for a philips head screw, remove it and the parts beneath it, you're looking for corrosion. If you find any clean it all up with fine sandpaper and swab in a mess of dielectric grease before reassembling.

You might have a poor connection in some or all of your signals causing the conditions you've described. Clean and grease every connection on the bike, you'll thank yourself in the long run for the added reliability, especially when you find a mess of crap before it finds you.
Alan

[Hondawggie]

Not sure about the type of signals you've got on that bike but the ones Honda used on the sohc 4's are the same type as my 81 CM400 has... what I'm getting at is remove the lens and look for a philips head screw, remove it and the parts beneath it, you're looking for corrosion. If you find any clean it all up with fine sandpaper and swab in a mess of dielectric grease before reassembling.

You might have a poor connection in some or all of your signals causing the conditions you've described. Clean and grease every connection on the bike, you'll thank yourself in the long run for the added reliability, especially when you find a mess of crap before it finds you.
Alan

I didn't get a chance to hook up my portable motorcycle jump-starter to my battery to check the turn signals and am hoping to do it today.  


I do not have enough knowledge to be able to say:  "If the battery is strong, and the bulbs and bulb sockets are clean, yet the signals still do not flash -- no connection problem would allow the signals to come on in their 'running lights' mode either."   I wish I could conclusively say "okay, battery is strong, bulb socket etc. are clean, still no flashing, so therefore the running lights can't possibly come on either."  If I knew enough to be able to say that -- it would indicate the flashing unit as going out since my running lights are coming on.  

I'm gonna check behind the lenses -- if there is corrosion, would the 'running lights' mode of the turn signals be fine but the flashing mode not work?  On the '80 cb900c, as soon as I turn on the ignition, the front turn signals come on in a 'less-brighter-than-when-flashing'  amount of illumination, for 'running lights'.  (Strangely the rear signals do *not* come on like that -- they stay dark.  And that is identical to what my 1976 cb400f does, the front signals are running lights, the rear signals are dark.)

This bike has some surface oxidation here and there because it was stored outside for a time.  I won't be surprised to find oxidation in the connects for the signals.  I just bought some dielectric grease at Kragen, the clerk there told me to get some when I went in to buy rear stop light bulbs for my 1998 Jeep Cherokee.  I did not even know dielectric grease existed before that.  

I hadn't thought to check the bulb socket and internal connects -- thanks for the tip.  I'm really hoping battery and/or connections will solve this.

The reason I spent the last week testing the headlight and turn signals is -- I had to re-connect the turn signals and re-install the front headlight ears and the headlight because the prior owner removed them, he had a big touring fairing on the bike.  Lucky for me he saved the stock signals and headlight bucket.  He had spliced into the stock cb900c harness and connected a bunch of wires for this fairing.

So when I removed the fairing, I found all these little blue plastic splicer connectors that are hinged to open up, you insert the wires then snap them shut and presto new splices into existing wires.  Luckily, when I removed (and sold) the fairing, I found that he had left the stock turn signal and headlight connections on the old harness, although those are now routed through those blue plastic splicers.

My fear is, because there's lots of the blue splicer connectors he added -- there might be an open somewhere that somehow allows the turn signals to come on for their 'running lights' mode but not for the 'flashing' mode.

[Alan F.]

...He had spliced into the stock cb900c harness and connected a bunch of wires for this fairing.

So when I removed the fairing, I found all these little blue plastic splicer connectors that are hinged to open up, you insert the wires then snap them shut and presto new splices into existing wires.  Luckily, when I removed (and sold) the fairing, I found that he had left the stock turn signal and headlight connections on the old harness, although those are now routed through those blue plastic splicers.

My fear is, because there's lots of the blue splicer connectors he added -- there might be an open somewhere that somehow allows the turn signals to come on for their 'running lights' mode but not for the 'flashing' mode.

Those are called 'scotch-locks' they're a way to tap into existing wiring in a quick and easy way and lots of people have used them. The down side to using them is that they 'bite' through the insulation to make contact to the wire strands inside, in doing this they usually cut a few strands inadvertantly. Combine a few cut strands with a bike being stored outdoors and electrical gremlins begin to colonize your bike.

To negate the effects of scotch locks on your harness you may have to locate each one and cut it out, then splice the wire back together with a soldered connection, then cover that with a layer or two of heat-shrinkable tubing. You may want to systematically do this as a preventive measure. And try a spare turn signal flasher if a strong battery doesn't help.

[wardenerd]

sounds like the ground problem i had on my 650c.  Check the ground

[Hondawggie]

I just put my portable jump starter on the bike.  The bike's starter motor spins fine, plenty of gusto.  And the headlight is bright, so is the high beam.
So there's power in the harness but no signals, still just the running lights.  Next will be a hopefully easy troubleshooting of the wiring, and the bulb sockets behind the lens and ground.  I have a feeling it will be a wire that over time, including me moving all the wires around to fit them in the headlight bucket -- one of the wires got broken clean through at one of those blue 'scotch lock' splicers.

[Hondawggie]

I've studied the wiring diagram for the turn signals and flasher.  The wiring diagram shows that the turn signal housing is supposed to supply its own ground -- but there are only 2 wires going to the turn signals:

- one wire in a turn signal connects the flasher relay to the turn signal by way of the turn signal switch (for the 'flashing turn signal' mode)

- the other wire connects the battery 12volts (through a fuse) to the turn signal (for the 'running lights' mode)

No ground wire!  When I've tested the turn signals they're sitting on the front fender (not mounted on the fork down tubes).

Does anyone know where to find a 1980 cb900c Parts List?  I want to see the detail of the turn signal assembly internals.   I already downloaded from this site the 900c shop manual but did not find a parts list for this bike.

Anyone know where to get a parts list for the 1980 cb900c ?
 

[medic09]

http://www.bikebandit.com/houseofmotorcycles/1980-honda-motorcycle-cb900c/o/m2011   See if what you want is in there.

Just to be thorough - try mounting those lights and then testing them.

[medic09]

This might be more to the point.

http://www.bikebandit.com/houseofmotorcycles/1980-honda-motorcycle-cb900c/o/m2011#sch4735

[Hondawggie]

Thanks Medic, I looked at the parts list for the front turn signal -- no ground wire I can see.   The electrical schematic shows the ground being provided directly at the lense housing.  It must be picking up the ground from the mounting brackets, which get the ground from a green ground wire connected to the triple tree from the headlight bucket and headlight ears.  That wire is fine.

I'm leaning towards the signal flasher relay has died.  

Here's why.  

If the ground for the turn signal was bad, since the exact same electrical ground is used by the (1) flasher relay wire, and (2) the wire for the 'running lights' mode, 12volts from the battery --

if the ground was bad then I shouldn't be seeing running lights.  The wire from the flasher relay and the wire from the battery provide 2 different operating modes of the front turn signal: 'flashing' and 'running light' -- but both wires use the same electrical ground.  So if the ground was the problem I wouldn't see any running lights, yet those work fine.

I think the flasher relay might have gone south.  I'm going to re-check the orange wire (the wire from the flasher relay for the left turn signal)  and check the light blue wire (flasher wire for right signal).  If I'm not seeing an alternating 12volts/0 volts/12volts between that wire and ground, and the same holds for both turn signals -- it's probably the flasher unit gone south.

If you think about it, the chance that both this orange flasher wire AND the light blue flasher wire both went bad is remote.  The one thing they have in common is the flasher relay unit.

I will also swap out the flasher bulbs to eliminate that as a possible source of the problem.  Hopefully will find out tomorrow if it's the flasher relay.

[wardenerd]

my bike had the same symptoms and had one ground wire running from the frame to the bolt holding the light stem on the left.  I put another ground wire from the frame to the opposite stem and the problem was solved instantly.  I am no mechanic but someone on the forum suggested it and since I had tried everything ekse I could I tried that and it worked. I had running lights but when I tried signals the lights dimmed and flashed sometimes and sometimes they didn't.

[bryanj]

If these are the semi rectangular, black plastic stem type they ground via the 8mm headed bolt that holds them on and its crap.
If you can, run a seperate green wire into the bulb housing and under one of the retaining screws,other end to green connector in bucket.
To test just get a long piece of wire and with the flasher lens off put the wire from a good ground to the metal bulb casing

[Hondawggie]

If these are the semi rectangular, black plastic stem type they ground via the 8mm headed bolt that holds them on and its crap.
If you can, run a seperate green wire into the bulb housing and under one of the retaining screws,other end to green connector in bucket.
To test just get a long piece of wire and with the flasher lens off put the wire from a good ground to the metal bulb casing

If these are the semi rectangular, black plastic stem type they ground via the 8mm headed bolt that holds them on and its crap.
If you can, run a seperate green wire into the bulb housing and under one of the retaining screws,other end to green connector in bucket.
To test just get a long piece of wire and with the flasher lens off put the wire from a good ground to the metal bulb casing

Okay to both you guys thanks, I will do that -- my symptoms are exactly that: running lights are fine, turn on the left turn signal  and the bulb goes dark, same on the right side. 

This bike (1980 cb900c) has rounded chrome turn signals, and Honda designed the headlight ears with a small nipple on the bottom outside of the turn signal ear that the round turn signal slides onto.  There is no ground wire leading up to a turn signal stem, and actually there is no turn signal stem of the kind I've seen on so many other metric bikes.

Here's the wiring schematic part showing that the turn signal housing itself is grounded:



There is a ground symbol you will see dropping just beneath each turn signal housing on the schematic, which on electrical schematics implies the ground needed by the bulb comes from the metal turn signal case itself.  And yet there is no ground wire (you won't find one in the schematic either).

The turn signal housing slides onto the small nipple at the bottom of the headlight ear.  There is a green ground wire attaching to a screw on the bottom of the triple tree and goes up into the harness.   Maybe that's the headlight and turn signal ground. 

I will take the advice and use a wire to forcibly ground the turn signal housing to the triple tree's ground point and see if that solves it and if yes, I'm going to run a couple of extra ground wires one per turn signal.  Thanks for the advice.

[Hondawggie]

Okay, I fixed the turn signals not flashing problem.  

Thanks to you folks who sent me off looking for a ground!  That was, in fact, the problem.

I now know why the flashers were working earlier in the week -- I had accidentally laid them on an already-grounded part of the frame.

So after your advice, I connected a jump wire from the turn signal casing to the chassis and voila, flash-city.

So I really got digging around in the jumble of wires that included the extra auxilliary harness of wiring to the prior owner's touring fairing, and the jumble of wires in the headlight shell that normally are there.  I found a lone green wire not plugged in.  But strangely it was not a round 'bullet-type' connector like all the other wires in the headlight bucket -- the green wire had at its end a 'blade-style' connector.  The connector was a female gender and so I had to figure out where the male part of this was, knowing it had to be in the turn signal/headlight area, and presto -- there was a small blade, a piece of metal of the headlight bucket itself, sticking out a bit in the back of the headlight shell.

I connected up the loose green wire to that and it's working now.

Thanks to all you guys for the help, I spent a lot of hours tracking this one down.  I have seen several different ways that the ground goes to the turn signals -- usually it's a 'washer-style' connector on the end of a ground wire that bolts directly to the turn signal stem.  I have never seen the headlight bucket plugged into ground like this. 

I will not waste time on this type of issue in the future -- first time in my life I had to fix an electrical problem with turn signals.

Thanks!