Headlight issue on my '97

[AutomotoMatt]

First post on the forum as this is the first issue I've had with the bike! I was doing a pre-MOT check and found that neither dip beam was working, tried new bulbs and still nothing. After some more investigation I found the relay wasn't working. The relay had already been changed to a non-standard one at some point before I owned the bike so I took the old one to my local shop who found it in their big catalogue and ordered one in for me. It's a generic starter relay rather than being specifically for lights but it worked before so I didn't have any doubts that a new one would be fine. I fitted it and checked I was getting power where I should before putting bulbs in - still nothing! After some more advice I checked the ground (am I correct there is just one point on the right hand side of the bike near the battery?) and the switch but I couldn't see how to get that apart so it has had contact cleaner sprayed in but still nothing

 

Is this a common issue and whats the solution?

 

Thanks,

Matt

 

 

[Grum]

Hi Matt.

Welcome to the forum.

Firstly do your Hi Beams work? And with Lo Beam Selected have you measured 12v at the Lo Beam Relay White wire? (assuming I have the right circuit diagram!). The relay Ground is the same for the Hi Beam Relay, Headlights themselves and the front Turn Indicators. So if your front turn indicators are working there is a good chance nothing is wrong with the ground side.

Also if both Hi and Lo are not working then that could point to your Starter Switch being faulty. The Starter Switch has additional contacts which remove the Headlight Relay power when you press the starter button. Sometimes this can get gummed up and the contacts don't re-make when you release the starter switch.

 

I'm assuming your headlight fuse is O.K.!

 

If you have any doubts about your Lo Beam Relay, for testing you can just swap it with the Hi Beam relay.

 

Do you have a circuit diagram of your bike? Get back to us with what you find.

[AutomotoMatt]

Thanks for the reply. I should have mentioned that the high beams work fine and the fuse is fine. I have measured 12v at the bulb connector but once the bulb is connected I get nothing

 

What you've said suggests I don't have an issue with ground or the starter switch but does that rule out the headlight switch?

 

I will try swapping the relays when I'm with the bike next (not till Tuesday unfortunately). I don't have a circuit diagram as I havent' got a manual

 

Matt

 

[DannoXYZ]

Hi Matt and welcome!

 

Stop wasting time and money swapping perfectly-working parts with brand-new perfectly-working parts! Nothing will change until you test and find problem component. Most likely it's not even bad part, but a corroded connector somewhere.

 

For example, to TEST if a bulb is good or bad.

1. remove unknown bulbs

2. hook up jumper cables to battery

3. hold ground terminal of bulb with jumper cable

4. touch terminal at tail of bulb with other jumper cable

5. touch other terminal on bulb

 

Does both bulb filaments light up?

 

Now you know for sure THAT bulb is good or bad. Quality of 3rd-party parts from auto-parts stores are notoriously bad. Many of them are bad right out of box and needs to be tested as well.

 

At moment, you have 2-sets of unknown bulbs that needs to be tested. Can't look at switches or wiring if you don't know if bulbs are any good.

 

 

[jefferson]

If you had 12 volts at the plug, but the bulb won't light, then I would say you have corrosion somewhere that won't flow enough when put under a load.

[DannoXYZ]

12 hours ago, AutomotoMatt said:

I have measured 12v at the bulb connector but once the bulb is connected I get nothing

 

This also implies that bulb is bad. Did you have +12 on BOTH bulb's dip-beam terminals? And they BOTH won't light any bulb?

 

Need to test all bulbs old & new to determine if they are indeed good or bad. This test is done by applying power directly to each bulb filament to see if they light up.

 

 

 

measuring each filament's resistance also works.

 

[AutomotoMatt]

I have a multimeter and have tested the four bulbs I now have and both filaments work in all bulbs. I've had power from the high beam circuit to the dip beam filament and that works, vice versa doesn't. The only part that has been replaced that I don't know works for sure is the new relay but since I'm getting power at the connector I had ruled that out. I suspected there was an issue when a load was applied to that circuit but I'm not sure what the common culprits would be after checking the earth so maybe it is the relay that's a duff? Once I've checked with the other relay I will know for sure, I hadn't thought of trying that

 

Thanks,

Matt

[Grum]

Here's a drawing of what I think is your bike wiring???

 Do you have 4 independent bulbs or 2 dual filament bulbs?

 

If your hi beams are working then that confirms grounds are good.

Also the main power for the lights is common for hi and lo beams. 

So its just a case of the lo beam relay sending power to both low beam contacts on the White/Black wire.

 

Does the relay you've replaced look and operate exactly as the hi beam one? Again, any doubts just place your known good working hi beam relay into the lo beam position and check the lo beam lights

 

It would be strange, though not impossible that you would have corrosion or bad connection for both lo beams and yet no issue with hi beam.

Note - the upper relay in the drawing is your lo beam.

 

You can download the Service Manual for your bike from this forum

 

[DannoXYZ]

8 hours ago, AutomotoMatt said:

...I've had power from the high beam circuit to the dip beam filament and that works, vice versa doesn't. The only part that has been replaced that I don't know works for sure is the new relay but since I'm getting power at the connector I had ruled that out. I suspected there was an issue when a load was applied to that circuit but I'm not sure what the common culprits would be after checking the earth so maybe it is the relay that's a duff? Once I've checked with the other relay I will know for sure, I hadn't thought of trying that

 

Thanks,

Matt

How did you divert power from high-beam circuit to dip-beam filament?

 

Since high-beam circuit works, you can use it to test your 2 dip-beam relays. Put one and other into high-beam circuit and see if they light high-beams. If yes, then issue is wiring to bulbs or wiring to relays or dimmer-switch itself. I find it easiest and fastest to just test harness points with multimeter rather than yanking and swapping parts. See tests below.

 

I could only find ONE wiring-diagram for 4th-gen. Are there different models for NA vs. Europe with different headlight behaviors? It's DOT regulation in U.S. that headlights have to be on full-time. Is it different in ECE countries where you're able to turn OFF headlights? So dimmer-switch would be 3-way with OFF-DIP-HIGH ???

[DannoXYZ]

Ok, here's diagram that's just headlight-related. Note after fusebox, power-circuits splits off into two independent circuits. One to power headlight-bulbs and one to control relays. 

 

TEST ALL EARTHS - even though they all join at some point, they each have independent wires up to that junction

 

1. measure resistance between high-beam bulb-connector's earth-terminal (G) and chassis ground. Ohms = ?

2. measure resistance between dip-beam bulb-connector's earth-terminal (G) and chassis ground. Ohms = ?

3. measure resistance between high-beam relay-socket's earth-terminal (G) and chassis ground. Ohms = ?

4. measure resistance between dip-beam relay-socket's earth-terminal (G) and chassis ground. Ohms = ?

 

TEST POWER CIRCUIT (key ON) - this one is easy.

1. measure voltage on Bl/R going into dip-beam relay. Voltage = ?

2. measure voltage on Bl/R going into high-beam relay. Voltage = ?

 

TEST DIMMER SWITCH (key ON) - backprobe switch's connector

1. measure voltage going into switch's Bu/W wire. Voltage = ?

2. measure voltage going out switch's W wire. Voltage = ?

3. switch dimmer to HIGH. Measure voltage going out switch's Bu wire. Voltage = ?

 

TEST WIRING BETWEEN HEADLIGHT SWITCH AND RELAYS (key on)

1. measure voltage going into W terminal on dip-beam relay socket. Voltage = ?

2. switch dimmer to HIGH. Measure voltage going into Bu terminal on high-beam relay socket. Voltage = ?

 

TEST WIRING BETWEEN RELAYS and BULBS (key on)

1. at each bulb connector, measure voltage at W/Bl connector. Voltage = ?

2. switch dimmer to HIGH. At each bulb connector, measure voltage at Bu/Bl connector. Voltage = ?

 

[Grum]

54 minutes ago, DannoXYZ said:

Ok, here's diagram that's just headlight-related. Note after fusebox, power-circuits splits off into two independent circuits. One to power headlight-bulbs and one to control relays. 

Very nicely done Danno. Simplifying the drawing like that should be of great assistance to the OP.

 

But not convinced yet that we have the right drawing of the OP's bike. But surely it would be very similar.

[DannoXYZ]

3 hours ago, Grum said:

Very nicely done Danno. Simplifying the drawing like that should be of great assistance to the OP.

 

But not convinced yet that we have the right drawing of the OP's bike. But surely it would be very similar.

Why thank you! 🙂

I've always heard that European bikes have ability to turn off headlight. I suppose that's easily done with 3-way dimmer-switch having dead neutral position where it doesn't power dip or high-beam relays at all. Rest of wiring can be exactly same.

 

How are headlights wired on bikes down unda?

[Grum]

39 minutes ago, DannoXYZ said:

 

How are headlights wired on bikes down unda?

I guess that depends on which gen you are referring to.

3 and 4 gens not sure of.

6 gen runs 2ea H4's for lo beam permanently on (except during cranking) and two H7's hi beam. All four beams are on when hi beam selected.

 5 gen for Australia not too sure of the headlight config however it only has the 2 bulb dual filament arrangement again lo beam on continuously(except when cranking).

8 gen the lo beam led's are never off even when cranking. 

7 gen 1200 not sure of.

[DannoXYZ]

Ah good to know, thanks! I was mainly interested in 4th-gen in question. Good to know how rest operates. So Oz headlights are similar to U.S. 

[AutomotoMatt]

Thanks for all the information, and the wiring diagram - although I'm not sure if it is right for my bike because of the differences with UK lighting. I think this one might be the right one 

 

 

To clarify a few things:

 

- I only have four bulbs as I have the 2 originally fitted p]lus two I purchased

- I took one of the bulb connectors apart to be able to try the different circuits on the different filaments

- When you turn the ignition on, no lights come on. There is a three position switch on the right handlebar with a fully off position, side light in the centre (a small single bulb within the headlight) then dip to the left. Right handlebar has the main beam switch along with the little trigger that flashes the main beam. EVerything works except dip beam

 

So I think my first step is going to be trying the high beam relay as that will tell me if the new one is working. Then checking connections as detailed by Danno if the relay is good and I've still got nothing

 

Matt

[Grum]

Matt. The drawing is very different to what we thought.

- You only have one lighting Relay and that is purely for Hi Beams. If your hi beams are working you don't have a relay issue. You have a hi beam filament in both bulbs.

- You only have one low beam filament of one globe NOT two. The other lo beam filament of the other globe is not wired. And the power for this is directly from your lighting switch when low beam is selected. This is via the White wire to the bulb.

Locate the bulb plug that has the 3 wires and measure for 12v on the White wire with Ignition ON, lo beam selected and headlight switch to ON.

 

Lets know if you have voltage on the White wire?

 

 

[DannoXYZ]

1. does high-beam work on BOTH bulbs when activated? 

That would give us clue to break in circuit.

 

2. Are they both H4 bulbs? With dip-beam filament ignored on one?

 

3. Have you restored your wiring back to full stock condition?

 

4. when you turn key on, do have any other lights on? Taillight? side-marker lights? liftle side light on main housing?

 

Forget all those tests I listed earlier, your circuits are simpler. Let's start with Grum's test for 12v on dip-beam filament on 3-wire connector.

[AutomotoMatt]

Sorry, that diagram is also wrong! I definitely have two relays so that must be another different version, is it possible the UK bikes are different again?

 

1 High beam works on both bulbs

2 Both H4 bulbs both wired to work on high and low but neither working on low. Power at both connectors for low when switched to low

3 Wiring is stock apart from the relay being non standard. It already had a non standard one when I got the bike and I can't fine the standard one available to replace it so it has a new non-standard one fitted

4 Everything else works as it should - dash lights come on when ignition is on but nothing else until you turn the side lights on (which is how it should be)

 

I'm not near the bike at the moment but from what I remember the three wires connecting to the back of the bulb are red blue and yellow. I can't remember which is which right now but across one set I get 12v when the main beam is on, the other set gets around 11v when just dip beam is on. You can't get power to both filaments at the same time. Both connectors are the same

 

Matt

 

[DannoXYZ]

That's correct that you can only have power on dip or high-beam terminals at connector. Dimmer switch dictates which relay is powered.

 

Try swapping two other relays into high-beam relay socket. This will at least confirm if 2 non-standard relays you have functions as they should. Then we go from there. No use trying to fix this if relays aren't working properly.

 

Can you also confirm your wiring colours match diagram I posted? only thing missing is additional switch that allows you to turn off headlights completely.

[AutomotoMatt]

Great, I'll try swapping relays and check wire colours when I'm with the bike on Tuesday and update

 

Matt

[DannoXYZ]

hmm... some issues for certain:

 

1. 12v & 11v are not same, when they should be. Points to wiring issue, perhaps corrosion on connector somewhere. 

 

2. also shows dead battery. Put it on charger immediately 

 

3. colours of red, blue, yellow at bulb socket shows your wiring is not factory standard. Has been altered, which may be why you're having issues.

 

 

OK, let's go back to my test checklist above. In addition to recording measurement values, also write down colour of wire you've tested. Then I can update schematic and see if anything obvious jumps out.

[DannoXYZ]

"are these not the relays you're looking for?"
 

https://www.ebay.co.uk/itm/392242865922/

 

Seems pricey! Standard Bosch 40a relay goes for U$D 3.00. These Honda ones do have copper terminals on power side for corrosion-free,  cool high-power transmission for many decades. But if your auto relay works, it works. BTW, let's see some photos of your compatible relays and relay sockets on bike.

 

 

[JZH]

FYI, the UK-spec 3rd gen does have two bulbs on low beam (unlike many of the European-spec bikes, which just have one), but unlike the US-spec and (I think) the Australian-spec bikes, the headlight circuit is not routed through the starter switch (because UK bikes have headlight switches and not always-on headlights).  Makes it a bit simpler to diagnose.

 

This isn't the best scan, but it is readable:

 

 

Ciao,

 

JZH

[Grum]

Thanks JZH. The dual relay configuration A appears to be what Matt the op has.

 

So Matt, you need to confirm you have a solid 12v on what appears to be the White/Black (hard to make out from drawing) wire on both bulb sockets with ignition to on, lights to on and lo beam selected. Check this and get back to us.

[DannoXYZ]

I took diagram JZH posted and copy & pasted A-config of headlights into diagram. Then coloured in headlight wires. It's functionally identical to U.S. model I posted earlier. With exception of momentary flash/passing switch. Start-switch is still used to turn off relays (therefore headlights) when you start bike. Then starter-switch powers dimmer switch to flip lights between dip & high-beam relays. I could not find switch anywhere that turns off headlights completely. So maybe this diagram isn't for UK either?

 

 

Matt appears to have non-standard wire-colours to his headlight sockets. I suspect he may have some non-standard wiring.