Highbeam

[Zombie Master]

1984 R100

So I noticed that my high beam doesn't come on.

When I press on the high beam flasher, the high beam comes on along with the blue indicator.

When I press the switch for constant high beam, neither the light or the indicator comes on.

I am using a led H4 replacement bulb.

I sprayed the switch with contact clean to no avail.

Any ideas?

[Kurt in S.A.]

Light relay?

Kurt in S.A.

[melville]

Do you have low beam, or just the parking light?

[Zombie Master]

Sooooo I still have parking light. I went into the headlight shell and found this:

I noticed that there was some dielectric grease on the connections for the H2 replacement. Could this grease be the problem? Could the grease have created resistance and cause the wires to burn?

There is a fan on the back of the Cyclops H4 3800 lumen bulb.

Can I just splice new wire in line?
I really need to figure out why this happened.

I was so pleased with the light, and the lower load on the charging system.

Have I learned yet once again that OEM is the only way to go?

PXL_20210921_233201348.jpg (278.19 KiB) Viewed 929 times

[gspd]

So I'm assuming low beam works OK.
The power into the switch (yel/white) is the same for high or low beam, so it's not a power supply issue.
The high beam "flash" supply is green and black, and we know that one works.
White wire to high beam is the same for both modes, and we know that one works.
Your problem is in the switch.
You have a corroded or burnt switch contact. In normal high beam mode there should be continuity between the yel/white wire and the white wire.
Flood the switch with contact cleaner and work it through its travel a few dozen times and see if that helps.
If not, they can usually be be taken apart and repaired, not that complicated.

EDITED A FEW TIMES (FOR CLARITY?)
I wrote the above based on your first post, the situation has changed I see.
looks like you pinched a wire. Does everything work now that it's un-pinched?
(It's not a wire overload issue. No need to replace the wire, just cut off the damaged part and splice it back together.)
If both low beam and high beam are not working, check your fuses.
That pinch most likely would have blown a fuse.
If only high beam isn't working, read my initial diag above.

[Zombie Master]

HI,

So the wires looks burnt, both the yellow and the white wire looks burnt.

I will have to shunt around the burnt section to see if it all works again.

If so I'll replace the burnt sections. will be tight working in the headlight shell.

I'll do that and confirm.

I really need to know what burnt the wires. Hard to see what's going on inside the headlight shell after it is closed.

I have a Pia H4 replacement bulb that should run cooler than a stock bulb, I could replace with that, but I really liked the LED which is probably working fine. I wonder how I can test it off the bike, with a battery that is not in the bike perhaps?

thanx.

[Rob Frankham]

One thing that still worries me is that, in your original post, you stated ...

When I press on the high beam flasher, the high beam comes on along with the blue indicator.

The High Beam actually uses that yellow wire so if the wire were damaged to the point that it was stopping the High Beam from working, it would inevitable also stop the flasher from working. I think there must be something else going on. Yes, by all means repair or replace the damaged wires but be ready to find it hasn't solved all of the problem.

A couple of other points...

1) Dielectric grease in the bulb connector is unlikely to increase resistance at that point as long as the actual connectors are tight... in any case increased resistance at the bulb connector will not cause increased current in the wire, in fact it will have exactly the opposite effect. Increased resistance at the bulb connector might cause overheating at the bulb connector but not elsewhere in the wiring.

2) Burning at the damage point(s) in the wiring indicates that the wiring itself at that point is overheating due to increased resistance at that point which will be due to the damage. In other words, the overheating and burning is probably due to the damage and not the other way around.

Rob

[gspd]

The High Beam actually uses that yellow wire so if the wire were damaged to the point that it was stopping the High Beam from working, it would inevitable also stop the flasher from working.

Not sure why they designed it that way but...
A yellow/white wire (from the headlight relay) provides the power to either the low beam (yellow wire) or to high beam (white wire) depending on the position of the switch.
A green wire (from the ignition switch) provides power to that same white wire for hi-beam 'flash'.
Some models used a red wire, always live, that allowed 'flashing' the high beam even with the ignition off.

ZM's problem looks like the yellow wire was pinched (partially shorted to ground) when putting the headlight back in its shell.

[Rob Frankham]

Yes, you're right... my bad. Yellow is low beam, white is high.

It follows that damage to the yellow wire has no bearing on the failure of the main beam. Certainly, no matter what, that yellow wire needs replacing or repairing... then the real cause of the problem can be chased.

I would help top know if the low beam headlight is working (after the yellow wire has been repaired...)

Incidentally, unless additional fuses have been fitted, the supply to the headlights isn't fused although the supply to the (grey) sidelight circuit (which also supplies power to the lighting relay) is. Failure of the 'lighting' fuse will mean that no lights will work but (bizarely) a short in the low beam or high beam circuits won't blow the fuse. Don't ask me why it's wired that way.

Incidentally (again), where did that diagram of the dimmer switch come from? I've never seen a BMW airhead dip switch with an 'off' position... those models which have a 'lights off' function (mainly euro spec models latterly) have a seperate lights off switch.

Rob

[gspd]

Incidentally (again), where did that diagram of the dimmer switch come from? I've never seen a BMW airhead dip switch with an 'off' position... those models which have a 'lights off' function (mainly euro spec models latterly) have a separate lights off switch.
Rob

The hi/lo switches never have a 'off' position. (There are no contacts for it in that pic.)
I don't know why Clymer illustrated it that way.