Electric problem on main beam - help please

[ralphy]

This is baffling me.

When switching on the main beam it doesn’t come on, worse still the dipped beam goes off! I’ve checked inside the headlight and the bulbs ok and the light relay seems to be working fine. The blue main beam indicator comes on when the main beam switch is used and that seems to be on the same wire (white) as feeds the headlight.

So effectively there’s two problems: 1) loss of feed to the main beam connector on the headlight, 2) loss of feed to the dipped beam connector when main beam selected.

I’m stumped!

R

 

[Fanum]

Sounds like a short through the dip beam circuit from the main beam

Obviously those two circuits are inches apart at the light end, so I'm guessing it'll be in the loom further back......probably where it's secured by cable ties and has cracked the insulation inside the bundle.

That's where I'd probably start anyway......though it's worth checking out the wiring schematics to see if the relay end of it might be a more plausible area for a short circuit.

I think my first action would be to cut away any cable ties holding the loom close behind the lights and giving it a bit of a massage with the lights on main beam to see if you can create a flicker in the dip beam.....

 

[Myke Rocks]

Sorry to be so presumptious but:

Have you changed the lamp?
You say it looks ok, but a change proves the point.
Myke

 

[ralphy]

Sounds like a short through the dip beam circuit from the main beam

Obviously those two circuits are inches apart at the light end, so I'm guessing it'll be in the loom further back......probably where it's secured by cable ties and has cracked the insulation inside the bundle.

That's where I'd probably start anyway......though it's worth checking out the wiring schematics to see if the relay end of it might be a more plausible area for a short circuit.

I think my first action would be to cut away any cable ties holding the loom close behind the lights and giving it a bit of a massage with the lights on main beam to see if you can create a flicker in the dip beam.....

I’m working my way through the loom now, according to the wiring diagram (Haynes manual) it’s got to be a break somewhere as the main beam indicator is working and that’s on the same circuit - IF I understand these things correctly...

Have you changed the lamp?
You say it looks ok, but a change proves the point.
Myke

Yep, tried a couple of spare H4’s in the headlamp with the same result.

I’m still baffled as to why a fault on the main beam would affect dipped though: dip has it’s own supply and main a separate one and I’m assuming switching on main would just supply that particular part of the bulb filament i.e. turning it on as well as leaving the dipped filament still on - or am I incorrect here?

R

 

[Micky]

Have you changed the lamp?
You say it looks ok, but a change proves the point.
Myke

+1

 

[Sleepy]

make sure the lamps have a good earth.. sometimes the lamp with a poor earth will go through the filament of another lamp, causing problems there..

 

[Myke Rocks]

Apologies, But:

When I replied I did not know the lamp type of your bike, this is undisclosed.

You need to clarify this.

For example, If H4, dip should extinguish when main beam is chosen.

If something else, you need to describe the beam arrangement.
E.G Dip always on, main coming on as well with main beam.
Thus it may be possible to point you in a direction.
Myke

 

[Ian J Hartley]

What bike is it?.

They are not all wired the same.

 

[ralphy]

I’ve double-checked the earth and there isn’t a problem with that.

It’s a R1150R, 2001 non-ABS.

The bulb is H4 & I didn’t realise that dip should extinguish when main is activated, so that’s no longer the second problem: thanks for clarifying.

R

 

[Micky]

They are not all wired the same.

Bit like UKGSer's then eh

 

[Myke Rocks]

I’ve double-checked the earth and there isn’t a problem with that.
It’s a R1150R, 2001 non-ABS.
The bulb is H4 & I didn’t realise that dip should extinguish when main is activated, so that’s no longer the second problem: thanks for clarifying.
R

OK, we are now all singing from the same hymnsheet.
You can eliminate the switch instantly because the main beam indicator comes on.
We can eliminate earthing problems because dip beam works.
I would guess, from previous experience, that the high beam spade connector inside the 3 pin socket which plugs onto the back of the lamp has burned out. This is a very common problem.
Pull the shroud off the 3 pin socket which plugs into the lamp and inspect. If it has burned, there are 2 solutions.
1. pull out the burned female spade connector and replace it with a proper right angle non insulated one, and crimp with the correct tool. I have them in my garage, but they are both hard to obtain.
2. go to a car breakers and cut the same socket and 100mm off an old car. Replace the one on your bike using solder and shrinkwrap.
Myke

 

[ralphy]

Thanks for the suggestion & help, Myke. I’d already checked the socket (having had a problem with one before on a car) and it was fine.

HOWEVER, I’ve now found the issue.

On the circuit diagram it shows the 4 wires involved from switches to relay and they all come to a common point, (labelled 56a FWIW) and so I needed to locate that.

After hours of faffing about:

I found the wires within a taped area holding a number of similar connectors, all visually looking ok - until I peeled of the cover to reveal the wires crimped
together or rather 3 of the 4 them, the one to the headlamp having worked its way out:

So thanks a lot BMW, some solder wouldn’t have gone amiss, eh?

R

 

[slimbo]

according to a bmw tech they never solder as it could come apart?or cause breaks next to the solder joint????? wtf!!!!!

 

[Myke Rocks]

according to a bmw tech they never solder as it could come apart?or cause breaks next to the solder joint????? wtf!!!!!

A spliced solder joint is mechanically and electrically perfect. It cannot come apart unless temperature is raised above the melting point of the solder. Re: vibration fracturing. I have never seen a vibration fracture in a soldered joint. This "scare" was raised because soild cables vibration fracture on many tbings, not just bikes or cars. However, the soldered joint, which is, effectively a solid cable for it's length, is only 20mm long, and so the rest of the cable acts as a the desired flexible.
Myke

 

[Ian J Hartley]

When they make up vehicle wiring looms, they work from the connector back into the loom. That way one person can consentrate on the assembly of one connector who passes his finished product on to someone who will lay his and all the other connectors on a peg board. this is so the bends and lengths can be determined accurately, before the loom is taped up. They take all the wires of the same colour and crimp them together in what is called a Tail. They use a crimp because it is quick and simple to apply and is the recognised best device for electrically connecting multiple cables together.

They do not use solder, because to a solder joint on a multiple cable is highly likely to lead to a dry joint, somewhere, most likely in the centre of the bundle. This would cause all sorts of problems.

 

[Bendy toy]

I have had many problems with soldered wires on older bikes. At least those that vibrate more than modern(ish) BMWs.
The very worst are the old Lucas bullet connectors. They are supposed to be secured with a little solder dab on the tip. But solder often tracks below the bullet skirt and the wire will fracture at that point.
Saying that soldered joints within a loom should be well supported and heat shrink sleeve gives added support. So as long as the wire can't flap about solder should be ok.

 

[Myke Rocks]

When they make up vehicle wiring looms, they work from the connector back into the loom. That way one person can consentrate on the assembly of one connector who passes his finished product on to someone who will lay his and all the other connectors on a peg board. this is so the bends and lengths can be determined accurately, before the loom is taped up. They take all the wires of the same colour and crimp them together in what is called a Tail. They use a crimp because it is quick and simple to apply and is the recognised best device for electrically connecting multiple cables together.

They do not use solder, because to a solder joint on a multiple cable is highly likely to lead to a dry joint, somewhere, most likely in the centre of the bundle. This would cause all sorts of problems.

Suggest you look at the cause of the fault on this motorcycle as described below. Company I work with use around 10,000 spade crimps every day. They are fabulous. Never a failure through bad connection.
However, to replicate such a good joint on a vehicle repair is practically impossible. Proper hand crimpers are very good, but do not provide the same quality of a connection as the Utilux machine can do.
Solder is impractical on a manufacturing line, too slow and labour intensive.
However, for a reliable repair which is impervious to corrosion it is second to none.
Myke