Topic: 1975 550F Electrical Gremlin - Need some guidance!!!

[dagersh]

Hi Guys,

I am having some problems with my 550F.  Simply put, I cannot get my Tail Lamp to function in the RUN position.  It will function in the PARK or PA on the ignition.

Now, using the wiring diagram, i know that the Taillamp function is handled throughout the bike with the Brown/White (Br/W) wire.  I have traced out the path of the Br/W from the Tailight all the way through the ignition switch, and there are no shorts.  Obviously, the bulb is fine as it works in PARK, and the brake light functions perfectly.  The front blinkers work, but do not light up as running lights - I am not sure if they are supposed to do this.

Which comes to the question - at least I think its the question...

How can I test the left hand handle bar switches?  its the last place that there could be a fault on the wire.  I did attempt to hook up a GL1000 (Goldwing) switch unit to test, but i could not get the tail light to come on with it either.  I also checked the ignition unit with one off of a '77 550 F, but no joy there either.

Is there a way to test for continuity through the switch unit?  Any other place I should be looking?

Thanks!

Dagersh

[CoachDoc]

Check the wiring diagram to see if there is a pertinent connection in the headlight bucket. If so clean both ends of the connector and see what you've got.

[dagersh]

Thanks Coach,

I have already been in there.  Connections are tight and and clean.  I can jump power to the tail through them using a spare wire on the + Battery feed.

I still think it must be in the switch housing itself, but I have no idea how to test for it.

Thanks for the input, it is much appreciated.

Gersh

[KingCustomCycles.com]

"I can jump power to the tail through them using a spare wire on the + Battery feed."   There you have it, done.

[dagersh]

Thanks KingCustom,

Won't that leave the tailight on all the time?  I am totally willing to use a splice to get the tail on....

Thanks!

Gersh

[TwoTired]

The tail light receives power on the BR wire.
It is routed to the Ignition switch and connects to both the PA (Park) and TL1 terminals.

When the key is put in the run position, the TL1 and TL2 terminals are bridged.  Since the TL2 terminal has BR/W connected to it, Br gets power from the BR/W wire.  The BR/W wire is powered from the tail light fuse.
The tail light fuse is powered by the BR/B wire which is jumpered to the Black wire in either the Headlight bucket, or the junction box under the left side of the tank. (I forget which).  Anyway the Black wire is powered from the key switch when in the run position from the red wire coming from the main fuse.

Helps to have a genuine Honda wire diagram, rather than being misled by Clymer's feeble attempts.

Cheers,

[dagersh]

Hi TT,

Glad I caught your estimable attention!

I am working with the Diagram from my Owner's Manual.  It is labled "CB550F-A".  I notice that the Br/W wires run through both the Tach and Speedo.  If I bulb is out on them, would that affect the continuity through the entire RUN circuit?

My harness is in very good condition, right now I have everything in the Headlight bucket disconnected, and I will be reconnecting everything.  When I got the bike, the starter button was shot, so I replaced the switch unit, and while I was in there I cleaned all the terminals and used Dielectric grease on them.  Everything else works just fine.

Looking into the bucket, there is an unconnected Brown wire, which corresponds to to the wiring digram.

In the junction under the tank, I do have a Brown/Blue wire coming from the handlebar Switch which is for the TS buzzer.  There are corresponding wires attaching to the buzzer in the headlight bucket.

Also in the Junction Box, there is another Brown/Blue wire which has a Black tube on it which plugs into a Y-Tube with 2 Black wires coming out of it.  It looks like they go inot the Right handlebar Switch with the Kill/Starter.  There is another unused Y-Tube with black wires, as well as another unused Y-Tube which goes to ground.

Where am I going wrong here?

Thanks!

Gersh

There is another Br/B

[TwoTired]

I am working with the Diagram from my Owner's Manual.  It is labled "CB550F-A".  I notice that the Br/W wires run through both the Tach and Speedo.  If I bulb is out on them, would that affect the continuity through the entire RUN circuit?

You are using the same diagram I am.  Kinda surprised you are still having an issue.  It all seems straightforward to me. 
The bulbs are wired in parallel, so there is no interdependancy as there would be with series wired bulbs.

Looking into the bucket, there is an unconnected Brown wire, which corresponds to to the wiring digram.

Yes. It is connected in some euro models that have a front "parking" light too.

In the junction under the tank, I do have a Brown/Blue wire coming from the handlebar Switch which is for the TS buzzer.  There are corresponding wires attaching to the buzzer in the headlight bucket.

[Waves hand] That is not the BR/B you are looking for...     

Also in the Junction Box, there is another Brown/Blue wire which has a Black tube on it which plugs into a Y-Tube with 2 Black wires coming out of it.  It looks like they go inot the Right handlebar Switch with the Kill/Starter. 

Black is +12V distribution.  Not surprising that it has a routing to the bar controls.  But, the black wires coming out of the main harness should be hot when the key is on.  That is the the source of power.  That Br/B jumper should take the power from the black main harness wire and route it to the tail fuse.  Then on to Br/wht. and the BR/wht routes back to the key switch terminal TL2  Which is connected to TL1 when placed in run position.  And, TL1 should have a brown wire connection which is tail light power.

Does your tail fuse ever get power?

There is another unused Y-Tube with black wires, as well as another unused Y-Tube which goes to ground.

Black should never go to ground.

You should be looking for black wire connections that come from the main harness as a power source.  You have to get that power to the BR/B that drives the fuse.

Easy peasy...

[Danno]

listen to two tired bud he is right but some times the ignition switch is actually the cause they can be taken apart cleaned and reassembled but before you do that look for a cruddy connection in the headlight bucket  and look for the wires he is telling you

[dagersh]

Thanks TT

Danno - I always listen to TT!

I will get back to work o it this PM!

Gersh

[dagersh]

Guys,

Here is where I am in my investigation.

TT - I have full power coming into the fuse on the Brown/Blue and out on the Brown/White. 

The ignition switch works 100%.  I tested it on my '77 CB550F and I get the Tail, gauges and turn signal running lights.

In the connections located under the tank, the Brown/White wire coming out of the main harness is only carrying a bit more than 3 volts.  Every other connection is getting 13+ Volts (I have the battery on a charger)

Is the Brown/White wire going bad inside the wrapped part of the wiring loom?

Also, the Brown wire leading to the taillight is also only getting 3+ volts.  When I switch to PA, there is 13+ volts going to the tail.

Again, thanks to everyone for the advice and guidance.

Gersh

[TwoTired]

Is the Brown/White wire going bad inside the wrapped part of the wiring loom?

Sure sounds like it.  Somewhere between the fuse output and under tank junction.
Didi you check out the wire connections in the fuse box.  Id' take the back of the box off and examine before unwrapping the harness.

Also, the Brown wire leading to the taillight is also only getting 3+ volts.  When I switch to PA, there is 13+ volts going to the tail.

Seems you just proved that the Brown IS getting connected to Br/W by the key switch.
When you fix the Br/W distribution issue, your tail light should work.  Note there is a tie point within the harness that connects four Br/W wires.  You'll have to unwrap the harness to find that junction.  (I suspect it is near the front) 
A tip to help put the harness back together as before disassembly.   As you unwrap, put twist-ties wherever a wire exits or joins the main bundle.  Later, when you wrap it back up (removing ties as you go), the harness will have the same shape as before the dissection.  You can use ordinary string, too.

Cheers,

[dagersh]

Thank TT,

I did pull the back cover off to check the continuity and condition of the wires and connections.   All clean, and full power.

Thanks for the tip on reassembly.  I will post my progress.

Cheers to you, sir!

Gersh

[dagersh]

Hi Guys,

So I think I have it figured out.  I pulled off the covering from the wiring harness to check the condition of the wires.  As it turns out, the Brown/White wires were fried at what looks like a factory 4-way splice.  I spliced in new 2 new wires after cutting back the deteriorated wire in order to see what my results would be.  I am left with 2 separate runs of Brown/White.  One run leads from the fuse block and the other leads from the ignition into the harness under the tank, and then up to the handlebar switch.  I know what you are thinking, and you are correct, one of these runs is not getting any power....

Now, I am assuming the original wires failed at a factory "crimp".  As it stands right now, I have full power to the Brown/White from the Fuse box all the way up into the headlight bucket where it makes a 4-way connection.  Right now, only the gauge leads are are plugged into the connector, and they light up just fine.  The other run which leads from the ignition switch through the harness under the tank and into the handlebar switch has little to no power.

This brings me back to my belief that my now repaired sections were once "crimped" together.  Think of the letter "X".  If I jump a wire from the powered leads to the gauges into the Brown/White on the ignition switch, all is well, and I have a taillight.

So, I am going to vampire the two runs inside the headlight bucket so that I can keep an eye on the connections.  I will post some pics to maybe make it clearer.

Anyone see a problem with my logic?

Thanks, as always, for the excellent advice!

Gersh

[TwoTired]

The wire diagram shows a 4 way splice in the harness,which, if I understand your post, you found to be faulty.
Why is it that you don't want to fix it there? (Restoring what was in place originally?)

I don't know why yours failed there, perhaps some abuse in the bike's 35 year history.  But, it is not a common failure, imo.

Cheers,

[dagersh]

TT,

The actual splice was no longer in existance.  It broke apart leaving two unattached ends and one frayed, but still connected run.  I found what I believe is a like splice on the Brown wires coming off the Ignition Switch.  The only way I can describe the splice, is it looks like 4 wires coming together, wrapped and then some sort of pressure and heat attached them with what is maybe solder...  When I saw this on the Brown wires, your comment regarding that the 4 Brown/White wires had a junction somewhere in the harness became clear.  My splice had been faulty and came apart.  There was a lot of oxidation on the wires and the sheathing was completely worn away.  I can only assume, there was a lot of resistance and the splce slowly burned away.

This was a major PITA, but what a great lesson!

Thanks you all, especially TT!

Gersh 

[TwoTired]

Wires wound together, soldered, and wrapped with green tape at the splice is what I remember seeing.

Glad you found the issue.   Congratulations on expanding your knowledge base.  Don't forget to share it with others!

Cheers,

[dagersh]

Hi TT,

That is exactly what I was talking about. 

Got the harness ack together, reassebled the bike and everything works fantastic.  The Front signals work as running lights, and well.. the bike is just flawless!  Took her for a flight on my local twisties with a big grin on my face!

Thanks again for your patience and knowledge.  I promise you I will help whoever I can.  Check out Ataylor's thread and see if I got him going in the right direction.

http://forums.sohc4.net/index.php?topic=96585.0

Gersh