Headlight main beam warning light - CB400/4 F2

[flatfour]

I've been helping a friend with his very recently purchased CB400/4 F2.

Whilst with me today for carburettor balance etc; he said that he had noticed that the main beam warning light came on with the lamp on dip and then extinguished on main beam. The head light itself works properly, mirroring the switch position.

I suggested that he swapped the main/dipped beam wires over in the headlight, which he did. The headlamp then worked in the opposite sense (i.e. main beam switch position was bringing on the dipped beam and vice versa, however the warning light still came on with dipped beam and went out on main beam.

The bike has been fitted with a new wiring harness (amongst much other work carried out prior to purchase) and, with my very limited electrical skills, I have run out of ideas to help.

Could anyone on here point to the problem?

Many thanks!

[McCabe-Thiele (Ted)]

There is a wiring diagram on this site. Sounds as though instead of reversing the main & dip you should have connected the main beam lamp to the correct connector.IIRC you need to switch the wires inside the headlamp. The white wire is dip beam. The Blue is main beam. The wire from from the instrument  panel main beam warning  lamp  should be fitted to the double connector on the blue cable inside the headlamp. The double connector has probably been fitted to the white dip beam in error.

UK model wiring diagram is attached below, US import has some differences.

[Oddjob]

It’s possible the bike has been fitted with a David Silver wiring harness, these are known to not follow the same colours as the original Honda wiring harness. So even though Ted is 100% correct in saying the headlight uses blue wires it may not do so now. However the original equipment will still have the correct colours on, the wiring from the headlight bulb for instance should still have the 3 original wires of green, white and blue. The wires from the panel should also be original. So find the blue wire coming from the panel, find the blue wire coming from the headlight bulb holder and make sure they connect to whatever colour wire the new harness is using. It should work then as planned.

[Lobo]

Edit… just seen Oddjobs thoughts, but will still post this in case relevant.

It could be that the new harness has had its connectors slightly muddled? It may be that the Blue & White loom cables have been incorrectly terminated….

In the pic below you’ll notice there should only be a single WHITE (low beam) connector and a double BLUE (high beam + Idiot light) connector - these come directly from the handlebar switch.

These connect directly to the bulb holder, with the additional Blue connecting up to the idiot Hi Beam bulb.

You should never connect mis-matched colours btw - so if you’ve a white male going to a blue female … there’s something wrong. (Excepting Oddjob’s comments!)

If the loom has been incorrectly fabricated, a bodge would be to cut the bullet off the idiot Blue, strip it back 10mm and shove it down the female loom Blue before then pushing home the Blue headlamp bullet. DO NOT leave any bare wire exposed as this will be +ve live at main beam ON. (A better way would be to make a Y connector with the correct female / bullets)

[Athame57]

It’s possible the bike has been fitted with a David Silver wiring harness, these are known to not follow the same colours as the original Honda wiring harness.

This is what I have, and no, the colours do not always make sense. Is the DSS version US spec or something?

[flatfour]

Many thanks to all for your helpful advice.

I'll pass it on and let you know the outcome.

[McCabe-Thiele (Ted)]

It’s possible the bike has been fitted with a David Silver wiring harness, these are known to not follow the same colours as the original Honda wiring harness.

This is what I have, and no, the colours do not always make sense. Is the DSS version US spec or something?

Not 100% sure but I think the UK & US versions have the same loom so you are left with some spare wires.

[Bryanj]

The theory is looms are the same but switches differ between countries

[Oddjob]

It’s possible the bike has been fitted with a David Silver wiring harness, these are known to not follow the same colours as the original Honda wiring harness.

This is what I have, and no, the colours do not always make sense. Is the DSS version US spec or something?

Reports from members who have fitted a DS loom is that whilst all the connectors are correct the wire colours are not. Some are but a lot differ, for instance a red/white wire could be a red/yellow on a DS loom. If you do a search of the forum you can see members asking for advise on how to wire them up but most return the loom as it's not really good enough. Ok I suppose IF you have some electrical knowledge of the bike but otherwise it's confusing as hell.

There was a thread just a few weeks ago, which is why it was fresh in my mind.

[McCabe-Thiele (Ted)]

That why I avoided the DS unit after reading about them on this site - the one from Elextrex had identical colours to my original loom they have gone up quite a bit since 2020 when I bought mine..

https://www.electrexworld.co.uk/acatalog/WH-377.html#SID=1158