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#1011200 - 05/13/18 09:58 AM Electrical Problem w/ headlight  
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Ja50n Offline
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Looking for advise for troubleshooting some electrical problems with my headlight. R1100RT (‘00).

I was riding and the low beam went out....no big deal, went to the store and put in a new H4 bulb but the low beam still didn’t work with the brand new bulb. High beam and the flash high position both worked, but couldn’t get low beam back. Checked fuses and didn’t see any that were blown.

Looked at a wiring diagram online and learned the power to the headlight goes thru the left handlebar switch with separate wires for low and high. So I took left side switch apart and looked for obvious problems (corrosion, loose wires, etc.). Sprayed it with electrical parts cleaner, and tested it — same results, no low beam but high works. Drove it like that for a little bit while I tried to figure out what was wrong with the low beam, a few weeks later the high beam stopped working. What? Maybe it’s the bulb (ignorantly hopeful) - of course not, replaced the bulb again — no change.

Bike hasn’t been used for a LONG time, this May decided it was time to do an overhaul, new battery and new clutch arrive this week. I’ll be done with the mechanical fixes but still have this electrical problem to resolve. Appreciate any troubleshooting advice you can offer. Thanks, Jason

#1011201 - 05/13/18 10:34 AM Re: Electrical Problem w/ headlight [Re: Ja50n]  
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kioolt Online
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My advice to you is to get a voltmeter if you don't have one. It can save you a lot of money by letting you check switches, fuses, connectors, etc without replacing them. You appear to know how to read an electrical diagram. I find it best to test circuits under power with a voltmeter rather then checking them with an ohmmeter. If you've got 12 volts under power with the load then your load should be on. Be sure to put both of your voltmeter leads on the bulb connector. If you put the ground lead on the metal frame it won't detect a bad ground for you.


2004 R1150RT 186,800 miles
1991 K100LT 128,700 miles
1982 R100RT 106,900 miles
Total 422,400 BMW miles

The cheapest thing on a BMW is the nut that connects the handlebars to the seat.
#1011206 - 05/13/18 12:41 PM Re: Electrical Problem w/ headlight [Re: Ja50n]  
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dirtrider Offline
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Originally Posted by Ja50n
Looking for advise for troubleshooting some electrical problems with my headlight. R1100RT (‘00).

I was riding and the low beam went out....no big deal, went to the store and put in a new H4 bulb but the low beam still didn’t work with the brand new bulb. High beam and the flash high position both worked, but couldn’t get low beam back. Checked fuses and didn’t see any that were blown.

Looked at a wiring diagram online and learned the power to the headlight goes thru the left handlebar switch with separate wires for low and high. So I took left side switch apart and looked for obvious problems (corrosion, loose wires, etc.). Sprayed it with electrical parts cleaner, and tested it — same results, no low beam but high works. Drove it like that for a little bit while I tried to figure out what was wrong with the low beam, a few weeks later the high beam stopped working. What? Maybe it’s the bulb (ignorantly hopeful) - of course not, replaced the bulb again — no change.

Bike hasn’t been used for a LONG time, this May decided it was time to do an overhaul, new battery and new clutch arrive this week. I’ll be done with the mechanical fixes but still have this electrical problem to resolve. Appreciate any troubleshooting advice you can offer. Thanks, Jason


Morning Jason

Troubleshooting the headlight circuits on the BMW 1100RT can be somewhat intimidating the first time you go into it.

The headlight circuit(s) is fairly complex & not as it seems at first glance.

You first need to verify that your headlight bulb is good on both high & low beam (more than one bike has been torn apart thinking a wiring problem when the only problem was a bulb filament not working.

You also have to verify that the headlight bulb ground circuit is working & that the terminals at the bulb attachment are not burnt brown or black.

Assuming that you DO HAVE a good bulb on both filaments, & the bulb ground is working & has low resistance, & that the terminals are not burnt brown or black.

Then, next you need to figure out what part of the headlight isn't working & if the tail light is working or not-- (this will give you a troubleshooting starting point)

The high beam & flash-to pass is powered from a different 12v entrance source than the always-on low beam (assuming no European off/on switch on the R/H handlebar).

Basically the headlight (hi/low/ & flash to pass) power starts at the battery, then to the ignition switch, then to the load relief relay, then splits-- one leg of the split goes to the RIGHT HAND handlebar switch pod to go through a jumper (or through a European on/off switch), then back across to the L/H handlebar switch then on to power the low beam.

The other leg on the split goes to the L/H hi/low/flash to pass switch to power the high beam (when turned on) & to power the flash to pass when activated.

The wire colors that you will be working with are Green/blue for the 12v into the R/H jumper (or switch), Green/blue for the 12v into the high beam & flash to pass on the L/H switch pod, yellow from the L/H switch to the headlight bulb low beam, white from the L/H switch to the headlight bulb high beam.

It might take a post or two back here to find the problem based on what you determine in your initial testing.

You first need to determine IF--

The yellow wire at the headlight bulb always has 12v on low beam with key on or engine running?

If the white wire at the headlight has 12v power with the high beam on, or flash to pass activated? Also, determine IF the dash high beam indicator light is on?

If you have 12v at the above wires, & the bulb is good, then determine IF the bulb brown wire has continuity to ground?

If the taillight is working & illuminated?

If the terminals that attach to the bulb are burnt black or brown.

So basically the green/blue wires going INTO the L/H hi/lo switch should have 12v with key on or engine running, the yellow wire coming out of the L/H switch pod should have 12v with key on or engine running on low beam, the white wire coming out of L/H switch pod should have 12v power when on high beam or flash to pass is activated.

See what you can determine then post back.






D.R. ___
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#1011230 - 05/14/18 03:18 AM Re: Electrical Problem w/ headlight [Re: Ja50n]  
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Thanks for the help!!! Here are my notes from testing today (DR’s questions followed by the result):

The yellow wire at the headlight bulb always has 12v on low beam with key on or engine running? —— No. it went to -0.05v for less than a second then to 0. Red probe was on back of headlight assembly yellow wire, also checked with red probe into H4 sockets yellow position, each time black probe was connected to battery ground terminal. Same result with H4 installed and uninstalled.

Does white wire at the headlight have 12v power with the high beam on, or flash to pass activated? —— No. voltage was 0 with red terminal on the H4 socket white wire and black probe on battery negative terminal. Same result with H4 installed and uninstalled.

Dash high beam indicator light is on? —— No. Same result with H4 installed and uninstalled.

If you have 12v at the above wires, & the bulb is good, then determine IF the bulb brown wire has continuity to ground? —— N/a, I don’t have 12v above (which is fortunate b/c I need to study up on how to check continuity. I bought the voltmeter today and don’t know how to do that yet. But I know it can, according to the package, hahaha)

Is the taillight working & illuminated? ——- TBD, bike is split open for a new clutch, and output shaft seal - can test that later this week when I get the parts and put rear ended and connections back together.

Are the terminals that attach to the bulb burnt black or brown. —— Nope doesn’t look look like it got hot at all.

So basically the green/blue wires going INTO the L/H hi/lo switch should have 12v with key on or engine running, the yellow wire coming out of the L/H switch pod should have 12v with key on or engine running on low beam, the white wire coming out of L/H switch pod should have 12v power when on high beam or flash to pass is activated. —— I Unscrewed the L/h switch, tested blue green voltage at connection point before entering switch, 0 volts with the key on and ABS/oil light flashing. Black test lead was connected to battery. On L/h switch, also checked horn and windscreen by actuating the button - neither worked. (Certainly appears power is not making it to L/h switch.)

Will recheck fuses tomorrow (ran out of light tonight). Looking forward to hitting it again tomorrow with any of your recommendations, hopefully the test results from today will help troubleshoot upstream of the L/h switch.

Thanks Again,
Jason

#1011235 - 05/14/18 10:48 AM Re: Electrical Problem w/ headlight [Re: Ja50n]  
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dirtrider Offline
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Originally Posted by Ja50n
Is the taillight working & illuminated? ——- TBD, bike is split open for a new clutch, and output shaft seal - can test that later this week when I get the parts and put rear ended and connections back together.




Morning Jason

With the bike split is the starter wiring disconnected??????

Your headlight needs the load relief relay energized to provide the 12v power. The load relief relay needs the starter solenoid wiring connected to the starter & starter body grounded as that is the low (ground) for the load relief relay's pull-in coil. (ie no starter = no headlight)


D.R. ___
Sent from my rotory dial wall phone!
#1011287 - 05/14/18 09:48 PM Re: Electrical Problem w/ headlight [Re: Ja50n]  
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DR, I didn’t know that either about the relationship btwn load relief and starter ground - good info. Starter wiring is connected but it’s not grounded....clutch arrives Tuesday 5/15 and I’ll get the rear half of the bike reassembled and carryon with the electrical troubleshooting. Will post again after testing the tail light with results.

#1011298 - 05/14/18 11:11 PM Re: Electrical Problem w/ headlight [Re: Ja50n]  
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dirtrider Offline
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Originally Posted by Ja50n
DR, I didn’t know that either about the relationship btwn load relief and starter ground - good info. Starter wiring is connected but it’s not grounded....clutch arrives Tuesday 5/15 and I’ll get the rear half of the bike reassembled and carryon with the electrical troubleshooting. Will post again after testing the tail light with results.


Evening Ja50n

If the starter is just hanging free now your lights will probably start working again when you bolt the starter up (or you can just ground the starter body using a jumper cable from starter body to the engine case).


D.R. ___
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#1011464 - 05/17/18 07:01 AM Re: Electrical Problem w/ headlight [Re: Ja50n]  
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Hey DR, I got the clutch and rear end back together tonight and ran the electrical test to continue trouble shooting the headlight issue ......With the key on the brake light illuminates, depress the brake lever and it gets brighter, both rear turn signals work too. I don’t know the electrical system well enough to know what that tells us. I took the fering off to make it easier for me to access the wires upfront too. Do I need to re-run the initial tests now that the starter is bolted back on? Cheers, Jason

#1011468 - 05/17/18 11:33 AM Re: Electrical Problem w/ headlight [Re: Ja50n]  
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dirtrider Offline
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Originally Posted by Ja50n
Hey DR, I got the clutch and rear end back together tonight and ran the electrical test to continue trouble shooting the headlight issue ......With the key on the brake light illuminates, depress the brake lever and it gets brighter, both rear turn signals work too. I don’t know the electrical system well enough to know what that tells us. I took the fering off to make it easier for me to access the wires upfront too. Do I need to re-run the initial tests now that the starter is bolted back on? Cheers, Jason



Morning Jason

You didn't provide your location so are we working on a U.S. 1150RT??? (if not a U.S. sold bike then do not use the below then post back with the country that the bike was initially sold in)

1)- First thing to check is that starter will try to crank engine with key-on, kill-switch-on & starter button pushed – This shows the low side of the load-relief relay has continuity to ground through starter.

2)-Next, with key-on check for 12v power on fuses #4 & #7 –This shows that the load relief is actually energizing & passing 12v power.

3)- Next, verify that your bike doesn’t have an added (European) headlight on/off switch on R/H handlebar switch pod.—If there is one make sure that it is turned on.

The above should cover the basics of having power to the headlight circuits.

If all the above is met then go through the initial tests that I wrote in my fist response.

Also, note IF the dash hi-beam blue dash light lights up when high beams are turned on (even if headlight hi-beam isn't lighting).


D.R. ___
Sent from my rotory dial wall phone!
#1011520 - 05/18/18 01:15 AM Re: Electrical Problem w/ headlight [Re: Ja50n]  
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Thanks for all help.....I’m learning a ton. I’m sure the thread will benefit others in the future as well. Here’s the latest:

2000 - R1100RT (US version) I’m the original owner, but it’s my first time with electrical problems so I’m a complete novice with the voltmeter.

1. I tried to crank it with the starter and nothing happened (key on, kill switch set to run). I still have the tank off - not sure if that matters, but thought I’d mention it just in case.....after doing everything else listed below I came back to the starter and looked at the engine wiring diagram and saw the starter relay has a connection to the clutch switch (although it’s not in gear, it is on the center stand, I pulled in the clutch, and what do ya know - crank-aroo! It did it.)
2. I do have 12v at fuse #7 (with red test lead on fuse and black to battery negative terminal with key switch on); also have 12v at fuse #4 with same set up.
3. It does not have Euro switch on the R/H switch pod.
4. High beam dash light doesn’t come on at all. (All 4 turn signals work, including 2 indicator lights in dash, and the speedo/tach lights work - these share similar ground path with the high beam indicator, so I’m guessing it must be the power supplied via the white wire causing the high beam indicator not to work?)
5. Went back thru tests from the first post.....(significant difference in d & e)
A. Bulb is good. Checked headlight bulb while it was removed from the housing, I connected bulb to battery with jumpers, both low and high elements illuminate when connected to their respective bulb prongs. Eliminated as a potential problem.
B. Parking light inside the headlight housing (aka side light) also works.
C. Headlight socket with bulb removed (test leads placed into where bulb prongs would go): yellow wire & brown wire = 0.035v; white wire & brown wire = 0.010v. Repeated, and got the same values. Then I ran same test a 3rd time only moving the black probe directly to battery post. Got the same values. Obviously power is not making it to the headlight socket.
D. NOTE Left handlebar switch: Blue/green wire in left handlebar switch now has 12.5v with the key on. Since it didn’t when I had the starter off, I checked the voltage on the other wires in that same L/h assembly (black probe was on battery terminal, red probe on specific wire, key switched on, low beam selected): blue green 12.5v, yellow 0v, yellow white 12.46v, white 0v, brown 0.16v, brown blue 11.6v. Brown yellow 12.5v.
E. Both the horn and windscreen (powered at left switch) - work properly.

I’m really not sure why the yellow wire and white wire aren’t playing nice with their friends and sharing power since it’s coming into the left handlebar switch on blue green wire??? Why do the other items controlled by the L/h switch still work? I didn’t understand the values of the brown and brown blue wires either. Although it’s not running yet, I’m very hopeful! Will attack it again tomorrow.

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