R1150RT headlight

[Afield]

Hello all,

My R1150RT-P headlight has stopped working. I need some help figuring out what its problem is. Here are the facts:

1) High and low beams do not work. Fog lights also do not work. The small running light does work. According to a layout of my fuses, the headlight is unfused.

2) I have a set of driving lights mounted but they are wired to a different wire. I used this wire (one of the RT-P leftovers) because it was hot when the lights are on. (On the RT-P, you can turn the lights off.) When the lights are supposed to be on, these driving lights are on.

3) All four bulbs light when juice is provided directly. The low beams and fog lights all light when juice is applied to the plug that enters the light assembly. I couldn't get the high beams to light, but was just guessing at red/black combinations on the 4 holes on the plug.

4) The brown ground wires appear to be in good shape, at least the parts I can see.

5) When I apply the leads of a multimeter to the male end of the plug going into the headlight assembly (the end that is mounted on the bike, not the headlight) I get no reading for any combination of red/black on any of the 4 plugs.

6) Hoping it was the plug, I checked the ends of the wires going into the plug. Same deal, no juice.

7) I suspected perhaps the high-beam switch and have started to disassemble it but it's getting scary.

Any advice on taking that switch apart or on looking elsewhere, please send it!
I'd love direct email replies at fieldt@gmail.com in addition to posts here for posterity.

Thanks in advance,

Andy Field

 

[mneblett]

Check the Load Relief Relay, and the wiring to the headlight downstream of the relay.

In case you are not aware: The main lighting and a couple other loads are routed through a relay which is normally closed by +12V from the ignition key, and the relay's coil grounds through the starter circuit (not enough voltage or current flow downstream of the relay coil to actually turn over the starter). This bit of wiring is what enables the next bit of cleverness: When the starter button is pushed, +12V is applied to the starter, which means the ground wire from the Load Relief Relay now sees +12V coming at the grounds side of the relay's coil. With +12V to both sides of the coil, there's no voltage difference to hold the coil in the closed position, so the relay opens -- what you see is when the starter button is pushed, the lights go out to reduce the load on the battery, and when the starter button is released, the lights come back on.

I suspect either the Load Relief Relay has failed, or the main lighting wire coming from the relay is broken. More likely the relay has failed -- not unheard of. Typically there are two failure modes: pull-in coil wont work (so the lights never come on, as in your case), or the relay contacts weld shut (so the lights never go off, even with the key removed -- I had that with an R100RT).

BTW, good diagnosis steps, and more importantly, a good summary -- that is what is leading me to the Load Relief Relay as the likely culprit.

 

[Afield]

Headlight woes

OK, I checked the relay. That's not it. Please give me some directions on downstream wiring. I am pretty good at this stuff once I've learned it the first time, but this is new. Thanks!

 

[jeff488]

There is a connector to the right and a bit above the headlight assembly.
You might check the contacts for corrosion. I had a weird headlight problem with my '04 RT and that's what it turned out to be.
Downside is, you have to take off the front tupperware to get to it, but once you're there it's easy.

 

[Afield]

I think I did

I think I did that already. Are you talking about the plain old plug that the headlight plugs directly into? It has 4 male pins? I checked it and it doesn't appear corroded, and when I applied the voltmeter leads to the wires entering the plug, I got nothing.

All the tupperware is already off for painting. Going solid black; you'll hardly be able to tell it's a police bike!

 

[jeff488]

I think I did that already. Are you talking about the plain old plug that the headlight plugs directly into? It has 4 male pins? I checked it and it doesn't appear corroded, and when I applied the voltmeter leads to the wires entering the plug, I got nothing.

All the tupperware is already off for painting. Going solid black; you'll hardly be able to tell it's a police bike!

Nope, not that one.
The one I mean is mounted to the right of the headlight assembly and has about 6 or so wires to it. It's mounted on the frame work close to the inside of the fairing. IIRC some of the headlight wires go to it from the 4 wire plug you mentioned and this is where it connects to the rest of the electrical system.
I wish I could be more specific, but it's been too long for me to recall.

 

[OfficerImpersonator]

This exact same thing happened to me, and it was the relay. I'm not saying you're wrong, but I'm saying I'd quadruple-check the relays under the seat.

The headlight acts as a switch for the other lights - if the headlight won't light, the relay doesn't power the other lights.

I lost my headlight, fog lights, turn signals, and crash-bar mounted driving lights this past summer. I was 400 miles from home riding with a couple of friends. We cut our trip short and took the most direct path back. When I got it in to my independent mechanic, he diagnosed and fixed the bad relay for $90.

Symptoms will vary (i.e. what lights won't come on) from RTP to RTP as every bike was configured and then unconfigured for LE duty by different agencies and/ or dealers, and so was wired and re-wired differently.

 

[dfmcintyre]

Same problem with mine

Turned out it was the ground, right where two or three ground wires come together up at the headlight assembly. The BMW tech that found the fault and repaired it said that the connector is crimped, not soldered at the factory. He soldered it, for the repair.

I asked him why in the world would they crimp. He said it's easier to train someone how to crimp then solder. Made sense to me.

Regards - Don

 

[jeff488]

Not surprised to hear it was a ground problem.
In my experience lighting weirdness is almost always caused by a bad ground.

 

[PGlaves]

I asked him why in the world would they crimp. He said it's easier to train someone how to crimp then solder.

But, apparently not how to crimp really well, or so it would seem.

 

[23217]

Turned out it was the ground, right where two or three ground wires come together up at the headlight assembly. The BMW tech that found the fault and repaired it said that the connector is crimped, not soldered at the factory. He soldered it, for the repair.

I asked him why in the world would they crimp. He said it's easier to train someone how to crimp then solder. Made sense to me.

Crimp connectors are used for applications where there are a lot of vibrations. Like aircrafts. The USAF only uses crimp connectors. Solder connections do not hold up under vibration. The preferred method is to tin the wire. Then crimp it. Then reheat the connector to cause the crimped connector to solder to the wire. You get the best of both worlds.