Author Topic: Wiring problem  (Read 375 times)

Offline sprinta

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Wiring problem
« on: June 13, 2018, 09:45:51 AM »
I have a wiring problem with my UK 73 750K2. It has the separate handlebar lights on switch and the pilot 'P' position on the RH handlebar switch.

Currently I have lost the pilot light and rear light with the ign switch in the run and park positions.

All the wiring diagrams I have only give the wiring detail without the h/b light switch and the pilot 'P' h/b switch position, so bit lost how to trace it at the moment?

Does anybody have a wiring diagram for this model or a schematic of that section of the wiring covering the separate h/b light switch, 'P' switch position and pilot/rear light?

I currently have 12v on the Brown wire at the back of the ign switch and 12v coming from the h/b light switch but 0v on the brown wire(s) which feed power to the pilot and rear light.

All other lights are working OK.

Thanks

Andy
« Last Edit: June 13, 2018, 09:47:34 AM by sprinta »

Offline Lobo

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Re: Wiring problem
« Reply #1 on: June 14, 2018, 04:27:54 AM »
Hi Andy,

From the sounds of it, you ‘simply’ have a break (loom or bullet connector) between the ignition switch BROWN (out) & Tail-Pilot light positive feed. I’m guessing that the instrument illum lights work.... this is the circuit which is energised with the lighting switch in h/b  (not P) .. and feeds back into the ignition switch (Position 1) ... thence through to the tail / parking light. Gawd...

With the ignition in Position 2; the tail / park get their supply directly from the RED perm live..

Because you have lost both tail & pilot in both P1 & P2 ignition switch positions I’d therefore reckon the break is (as mentioned) is somewhere downstream of the Ignition Brown, but before it splits into forward / aft routings to the & Tail / Pilot lamps.
Because both Tail & Pilot have failed their respective earths are less likely the culprit...

One other possible gotcha might be corroded bullets / wiring / loom (in the above area) which can carry the minute current of your voltmeter test, but ‘fail’ under the load of light bulbs. This could be easily checked by running a hot-wire directly from the brown (ign switch output) to the lamps... ie by passing the loom / bullet connectors.

Attached a wiring diagram I use - not perfect, and not an English K2... but near enough. They are indeed hard to find... (the colours are crap, the BROWN wire is point TL2 on the switch)

Good luck,
Simon
« Last Edit: June 14, 2018, 04:34:32 AM by Lobo »

Offline sprinta

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Re: Wiring problem
« Reply #2 on: June 14, 2018, 03:07:32 PM »
Thanks for the reply and advice Simon.

Yes all the 'idiot' and other lights are fully working. As you have indicated there must be some sort of break in the power feed to the brown wire, which feeds the power to the pilot and rear light.

The bike has a new wiring loom and was working perfectly OK. I have checked all the connections in the headlamp and cannot find anything not connected.

Main problem at the moment is that without a wiring  diagram for the UK model, which has the separate handlebar lights on/off switch and the parking, 'P', position on the RH handlebar switch it is difficult to check/trace  how the power is fed to the brown wires that feed the pilot/rear lights as it must go, by some route, via the handlebar lights on /off switch and the 'P' position on the handlebar switch, none of which are shown on any wiring diagram that I can see/find?

It is also slightly confusing because the power to the pilot/rear light must go through the handlebar switches with the ignition in the P1 'run' position, which you have indicated is via the red wire but runs directly from the brown wire on the ignition switch in the P2 'park' position so there has to be two independent circuits but with a common wire to both somewhere, which at the moment I have not been able to deduce?  'O' for a nice schematic of the circuits!

Will do some checks/tests directly with a wire from the ign switch as you have suggested.   

Andy
« Last Edit: June 14, 2018, 03:35:56 PM by sprinta »

Offline Lobo

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Re: Wiring problem
« Reply #3 on: June 15, 2018, 05:18:10 AM »
Hi again Andy,

Attached a modified circuit diagram as to how my K2 was wired, iaw the UK additional LH Main switch and its external wiring (ugh). I read that it was incorporated to stop you plunging yourself into total darkness as you went from HI to LO Beam... and thence inadvertently to P (= actually OFF). Aargh..
(still bloody useless as you were left with a wee park lamp ...)

So... this add-on UK switch ADDITIONALLY connects the BLACK Ignition supply to the BROWN/WHITE Inst illum lamp circuit ...  ie see the attached diagram, noting that switch terminals TL & IG are effectively connected when this UK switch is ON.

The ‘UK’ switch then controlled power to the Park / Tail lamps via the Inst Illum circuit with the IGN Switch in the P1 position.


So... with the Ignition Switch in P1

(1) UK switch OFF ... P= no lights at all, L=LO+Park+Tail+Inst, H=HI+Park+Tail+Insts
(2) UK switch ON..... P=Park lamp+Tail+Insts; L=LO+Park+Tail+Inst, H=HI+Park+Tail+Insts 


With the Ignition Switch in P2..

(1) The above BLACK feed / Inst BROWN/WHITE circuits not energised, and the tail / park lamps now get their power from the perm live RED.

Personally, I hate the crappy UK Switch and it’s external wiring, and so have deleted it. The choice was to return to the ‘standard’ Honda wiring & occasionally plunge yourself into complete darkness... or instead, splice the BLACK directly into the BROWN / WHITE.
I’ve gone for the latter... the downside being that the lights come ON immediately with ignition P1, ie behave as in (2) above.

Just a final comment on the typical wiring diagrams... such as I’ve attached. The diagram show 4 different RH light switch selections, ie P (OFF), H (HI Beam), Neutral (switch some mid position) and L (Low Beam). You have to read them in isolation... ie one switch position at a time.
SINCERE apologies if I’m teaching you to suck eggs here... 😳!

(1) the LIGHTING DIMMER SWITCH OFF box shows the switch in the P position, no connections are made, everything is actually OFF. Dead. Nada.
(2) the next box down, ‘HIGH’ illustrates the switch internal connections with H selected, ie the IG (ignition) is connected to TL (tail light) and also HB (High Beam)
(3) the next box down, ‘NEUTRAL’ shows the switch in some neutral / mid position, and shows all connnections are made / lighting is safe. (Ie IG connected to TL, and HB, and LB (Low Beam)
(4) the lowermost box ‘LOW’ shows the switch internal connections with L selected. (Ie IG connected to TL and LB)

Read the COMBINATION Switch in the same way... (to you & me it’s the Ignition Switch with its 3 positions, OFF, P1 (Ignition ON) .... & P2 (Park)

Hope this helps.. in my modified wiring diagram I’ve shown the front Park / pilot lamp wiring in blue.. (should be BROWN)...limitations of my iPad alas.

Cheers and good luck, again, accept my apologies if boring you with the obvious.
Simon

PS - Andy, I’m not saying this is how a 1973 K2 was out the Dealership.... I’m rather saying how mine was wired when I became its ‘next minder’ it in 2012.
« Last Edit: June 15, 2018, 06:46:48 AM by Lobo »

Offline K2-K6

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Re: Wiring problem
« Reply #4 on: June 15, 2018, 09:03:37 AM »
Have you verified that the ignition switch making all of the contacts it should do?

http://www.sohc.co.uk/index.php/topic,16187.0.html

We were talking about it on the above thread recently and could assist if you meter the switch through,  especially as you're using a new loom.

Offline sprinta

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Re: Wiring problem
« Reply #5 on: June 15, 2018, 09:38:53 AM »
Hi again Andy,

Attached a modified circuit diagram as to how my K2 was wired, iaw the UK additional LH Main switch and its external wiring (ugh). I read that it was incorporated to stop you plunging yourself into total darkness as you went from HI to LO Beam... and thence inadvertently to P (= actually OFF). Aargh..
(still bloody useless as you were left with a wee park lamp ...)

So... this add-on UK switch ADDITIONALLY connects the BLACK Ignition supply to the BROWN/WHITE Inst illum lamp circuit ...  ie see the attached diagram, noting that switch terminals TL & IG are effectively connected when this UK switch is ON.

The ‘UK’ switch then controlled power to the Park / Tail lamps via the Inst Illum circuit with the IGN Switch in the P1 position.


So... with the Ignition Switch in P1

(1) UK switch OFF ... P= no lights at all, L=LO+Park+Tail+Inst, H=HI+Park+Tail+Insts
(2) UK switch ON..... P=Park lamp+Tail+Insts; L=LO+Park+Tail+Inst, H=HI+Park+Tail+Insts 


With the Ignition Switch in P2..

(1) The above BLACK feed / Inst BROWN/WHITE circuits not energised, and the tail / park lamps now get their power from the perm live RED.

Personally, I hate the crappy UK Switch and it’s external wiring, and so have deleted it. The choice was to return to the ‘standard’ Honda wiring & occasionally plunge yourself into complete darkness... or instead, splice the BLACK directly into the BROWN / WHITE.
I’ve gone for the latter... the downside being that the lights come ON immediately with ignition P1, ie behave as in (2) above.

Just a final comment on the typical wiring diagrams... such as I’ve attached. The diagram show 4 different RH light switch selections, ie P (OFF), H (HI Beam), Neutral (switch some mid position) and L (Low Beam). You have to read them in isolation... ie one switch position at a time.
SINCERE apologies if I’m teaching you to suck eggs here... 😳!

(1) the LIGHTING DIMMER SWITCH OFF box shows the switch in the P position, no connections are made, everything is actually OFF. Dead. Nada.
(2) the next box down, ‘HIGH’ illustrates the switch internal connections with H selected, ie the IG (ignition) is connected to TL (tail light) and also HB (High Beam)
(3) the next box down, ‘NEUTRAL’ shows the switch in some neutral / mid position, and shows all connnections are made / lighting is safe. (Ie IG connected to TL, and HB, and LB (Low Beam)
(4) the lowermost box ‘LOW’ shows the switch internal connections with L selected. (Ie IG connected to TL and LB)

Read the COMBINATION Switch in the same way... (to you & me it’s the Ignition Switch with its 3 positions, OFF, P1 (Ignition ON) .... & P2 (Park)

Hope this helps.. in my modified wiring diagram I’ve shown the front Park / pilot lamp wiring in blue.. (should be BROWN)...limitations of my iPad alas.

Cheers and good luck, again, accept my apologies if boring you with the obvious.
Simon

PS - Andy, I’m not saying this is how a 1973 K2 was out the Dealership.... I’m rather saying how mine was wired when I became its ‘next minder’ it in 2012.


Thanks Simon

Will digest and have a good go over the weekend to see if I can try and better understand the circuits and sort the problem?

However, I do note that I have also encountered the Neutral light becoming intermittent so there may well be a link there?

Andy   

Offline sprinta

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Re: Wiring problem
« Reply #6 on: June 15, 2018, 09:44:50 AM »
Have you verified that the ignition switch making all of the contacts it should do?

http://www.sohc.co.uk/index.php/topic,16187.0.html

We were talking about it on the above thread recently and could assist if you meter the switch through,  especially as you're using a new loom.

Thanks for the reply and link.

Since when I got the bike it came with seperate ign and seat keys and no key for the steering lock I replaced them all with a new Honda lock set. The ign has the earlier round connector and I don't believe that as new should have any contact problems and as indicated the lights had been fully working but for some reason the pilot and rear light have ceased working  in both the P1 and P2 ign positions.

Andy

Online hairygit

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Re: Wiring problem
« Reply #7 on: June 15, 2018, 11:34:56 AM »
I assume you've checked the sidelight and tail light bulbs are actually okay and not blown, and the bulb holders are clean and corrosion free? (stranger things have happened)
If it's got tits or wheels, it's hassle, if it's got both, RUN!!!

Offline Lobo

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Re: Wiring problem
« Reply #8 on: June 15, 2018, 04:18:46 PM »
Ha! hairygit - good point. Eggs on faces all ‘round if you’re right. Sprinta, for gawds sake don’t admit to it if bulbs blown etc!

Offline mickwinf

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Re: Wiring problem
« Reply #9 on: June 15, 2018, 06:14:54 PM »
I had a similar problem on my 550, turned out to be the ignition switch, also do you have a separate fuse for the side lights?
Love the 500/4 and 550 own 2 at the moment.

Offline sprinta

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Re: Wiring problem
« Reply #10 on: June 15, 2018, 08:34:07 PM »
First thing I did was the check the bulbs, both OK. As indicated 0V on the Brown wire to the bulbs but 12V on the Brown wire on the back of the ign switch. So will do some further tests/check over weekend to see why?

It only have the single fuse, so if that had gone nothing would work.

Offline Underdog1

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Re: Wiring problem
« Reply #11 on: June 15, 2018, 09:10:53 PM »
I’ve got s little bit of wiring to do this weekend on the fuse box. Got some 1mm thinall wire rates to 16a, seems very thin. Anyone know what wire size we should be using on these bikes?

Offline Lobo

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Re: Wiring problem
« Reply #12 on: June 16, 2018, 01:21:30 AM »
Hi Underdog. Given the fuse is rated at 15A, anything over this should be fine. Belt’n’braces wise I personally might have gone up a notch (1.5mm?); esp as you say, it’s such a small dia and so loom thickness is not an issue.
« Last Edit: June 16, 2018, 01:23:06 AM by Lobo »

Offline Lobo

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Re: Wiring problem
« Reply #13 on: June 16, 2018, 02:12:15 AM »
Sprinta... these of any use?

Offline BigAl

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Re: Wiring problem
« Reply #14 on: June 16, 2018, 10:27:21 AM »
I’ve got s little bit of wiring to do this weekend on the fuse box. Got some 1mm thinall wire rates to 16a, seems very thin. Anyone know what wire size we should be using on these bikes?
Try the 2mm thin-wall cable. The combined diameter (copper & insulation) of the original 1mm low temperature rated pvc cable is 2.3mm, as the 2mm thin-wall cable is 2.7mm. Very little difference with the overall harness thickness...current rating of 2mm cable is much higher, reduced volt drop issues and crimped connectors, particularly the insulation 'cord grip' are more secure when fitted to 2mm thin-wall cable than 1mm thin-wall cable (as image)

Alan
Current bikes:-
Honda CB750 K4 (1974) USA
Honda XL500S (1980) UK
Honda CD175 sloper (1968) UK
Honda CB1100A (2013) UK
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