Topic: 1975 CB550K headlight wiring with 1977 right switch

[db22]

My 1975 550K project bike is coming along well enough, but the only right-hand switch I have on hand is a '76 or later model with no on/off switch for the lights. Can someone give me an idea what needs to be done to adapt the 1975 wiring to "on-all-the-time" lights? I can get the brake light to work, but I haven't managed to make the headlight and taillight light up.

There are five wires from the switch -- yellow/red and black for the starter, and black/white and black for the kill switch. That leaves a single black wire that ought to go -- somewhere. Maybe.  Is a jumper needed in the loom to get the headlight/taillight circuit to light up when the key is turned? There is a leftover brown wire with a female connector in the bucket that I can't find a use for, but the meter shows it isn't hot when the key is on.  Thanks!

[Sprocket75]

White wire and blue wire control low beam and high beam and should have their own plug which plugs into headlight.
( 3 prong) Wire them in the bucket to their respective colors. Also make sure the rest of the wires from left hand switch are wired correctly as one of them is the switch feed for the other wires. Tail light should be the brown wire that you found. Make a jumper from keyed hot to test. Also, the tail light is supposed to be fed directly from the ignition switch... but was not on my bike. There are several wiring diagrams available for download on this site too.

[bryanj]

There should be 3 wires to the starter button, one being black and something, please check and get back to us

ALSO check what the two small wires on the starter solenoid do

[db22]

Everything runs now, except the headlight and taillight -- engine starts, horn honks, turn signals work, brake light works. Blue, white and green headlight wires are hooked up, and I'll try a jumper from keyed hot to that dangling brown in the bucket. There does seem to be a nasty parasitic drain on the battery -- not when key-off, but just when using the starter. Got plenty of 15A fuses for tests...  Thanks to both of you for your advice!

[MoMo]

brown in the shell is spare, jumping to it will not help.  Do you have a red/blue wire?  I think that is the color that feeds the left switch.  r/b in and then the high/low switch feeds either the blue or white.. If you have the red/blue jump the spare black to it...Larry

[db22]

Bryan -- my wiring diagram shows only two wires from the starter button, yellow/red and green/red (which appears to be solid black on this switch). Connecting them to their respective colors on the loom gives me a live starter button. The two small wires from the solenoid are tucked tightly behind the electrical panel, and have given no trouble in the past.

Momo, do you mean a red/blue on the loom or the switch? The switch has a black/red, a yellow/red, a black/white, and two solid blacks. One of the solid blacks has continuity with the yellow/red, and connecting it to the green/red on the loom gives me a working start button. The black/white from the switch has a female bullet, and connects to a male black/white from the loom.

[Duanob]

Do you have both wiring diagrams? That would help to figure where each wire goes. Your drain might be because the headlight is on all the time even when starting with the newer bikes. The 76 had an off switch in the start button that alleviates power drain. It cuts power to the headlight only when pushing the start button. My guess is somehow this isn't transferring over from the newer switch to the older bike.

I did a complete diagnostic of my start switch a couple months back because my headlight wouldn't work anymore. I chased wires all over the bike. It came down to the start button and wiring assembly was falling apart and I needed a new RH control. Got that and all works perfect. Unfortunately my brain blocked it all out and I don't rememebr which wires go to the start/headlight off button.

[MoMo]

Bryan -- my wiring diagram shows only two wires from the starter button, yellow/red and green/red (which appears to be solid black on this switch). Connecting them to their respective colors on the loom gives me a live starter button. The two small wires from the solenoid are tucked tightly behind the electrical panel, and have given no trouble in the past.

Momo, do you mean a red/blue on the loom or the switch? The switch has a black/red, a yellow/red, a black/white, and two solid blacks. One of the solid blacks has continuity with the yellow/red, and connecting it to the green/red on the loom gives me a working start button. The black/white from the switch has a female bullet, and connects to a male black/white from the loom.

The black/red is the feed for  the headlight.  Do you have 12v there?  I don't have a diagram in front of me and was thinking it was red/blue, what color wires come from the left switch?  Should have orange, blue, light green and another color...Larr

[bryanj]

You are looking at the wrong diafram for the switch mate and you need to be VERY carefull with the starter button wires as the operating system changed a lot which is why I asked aboout the solenoid wires, don't mean to be rude but i ask the questiopns for a reason!

[db22]

Bryan: Of course, you are right -- there is a separate diagram for 1977 switches, which I have never found. In an attempt to make the switch match the diagram I have, this morning before work I tried using the lower half of the 1977 switch, ignoring the red/black wire from the starter, with a battered but still apprently good upper half of a 1975 switch. Result -- strong cranking and starting, bright turn signals, but still no lights.

Here's another perhaps related question: the PO had grounded the taillight to the frame, which doesn't appear in the diagram. My taillight has only two wires, one solid red, one solid black. One goes into the green/yellow brake light wire, the other into the brown taillight wire. The brake light works, but the taillight does not. If the taillight fixture is not properly grounded, might that condition prevent the entire lighting circuit from operating? Both of my 550s were in run-down, jerry-rigged condition when I got them. Maybe my attempt to reconnect everything according to the wiring diagram is messing up the PO's improvised solutions. Whaddaya think?

[bryanj]

OK the Black/red needs to connect to the wire that feeds the dip switch which i think is brown with a red tracer but not sure.

PLEASE check the solenoid as the early ones work by grounding the wire at the switch whilst the later ones are powered by the switch and ground at the solenoid.

Attached is a European wiring diagram which has a lights on/off switch on the RH side but everything else should be the same.

As to the rear light it sounds like you have an aftermarket unit which needs to have the casing grounded to work properly as the original bracket AND light are rubber mounted and therefore insulated but no it would not affect the rest of the lights. i seem to remember a "Jumper" wire in the headlamp that made the side light work with the headlamp but it is a long time ago, enlarge the scan and check it out

[db22]

Bryan -- Many thanks for the later wiring diagram. I have to work all day today, but tomorrow the weather is supposed to be sunny and 50F, so I'll try to get the old bike wired correctly per your good advice. Yes, all the tail lights I have on the bikes are aftermarket, only two wires each.