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High beams and running lights gremlin (2/2 solved!)


bianchini

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UPDATE: figured out the running light issue (detail below).

 

Figured out the headlight issue: severed wire within the wires/electrical harness going from drivers side over to passenger headlight. so simple, yet stumped me for a fews days!

 

So I was working on the car and I was testing some electrical stuff and I have come to find out that my passenger high beam shuts OFF when I pull or leave the high beams on AND my passenger side running light at the front does not turn on. the turn signal works, but the running portion does not turn on. Here is what I have tested so far:

 

- All bulbs work on both sides - swapped sides and no issues

- all fuses are working- tried swapping those around too and no issues

- tried messing with the 3 relays at the front - pic attached

- tried testing if amps/volts are getting to the passenger side, but not getting any reading there... 

 

the confusion I am having is 

1- why just the passenger side?

2- what is the very front relay with the "L" on it for? I tried swapping them all around in different combos and have found the

  • "reg" is for regular beams
  • "HI" is for high beams (both push and pull on the stalk)
  • no idea what the "L" does..... H

 

 I'm no electrician, so please explain like I am 5 yrs old!

 

IMG_0753.jpg

Edited by bianchini
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I just went through an exhaustive diagnostic / repair procedure on a 75/76 car with three relays. Here's what you should have:

 

Horn relay (possibly only 3 wires to that one, if memory serves)

 

Hi beam relay

 

Lo beam relay.

 

Often / always BMW puts the left low beam on a different fuse than the right low beam...for safety reasons.

 

Hi beams should both be on the same fuse.

 

Could be a bad relay (or two)...and unrelated (probably) to the running light in the turn signal assembly. 

 

Hope this helps! The wiring diagram for this year/model is tricky. Thanks to Siegel, I found a diagram that worked on the BMW2002tii.org site.

 

Link to appropriate diagram /PDF here:

 

http://www.2002tii.org/diagrams/bmw2002-usa-1975.pdf

 

Hope this helps get you started at least!

 

Paul

Edited by wegweiser
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Paul Wegweiser

Wegweiser Classic BMW Services

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According to my '02 shop manual, squarelights have two separate fuses for the low beams (#9 left low beam; #10 right low beam).  Fuse 11 is for the high beams, and there's a relay for the high beams (but not for the low beams).  So the relay on your car marked "L" is not for the low beams; it's probably for the horn.  I believe the center relay is for the high beams, and since the highs are served by a single fuse and a single relay, and only the pax side high beam isn't working, that should absolve both the relay and fuse.  I'd check the headlight itself--if you have sealed beams, the high beam filament may be burned out/broken, or it's not making good contact with its socket.  If you have European headlights with a separate bulb and reflector--same thing--the high beam filament may be broken. 

 

You can test both by removing the bulb and connecting an ohmeter across the terminals (high beam and ground).  If the reading is infinity, then it's an open circuit (broken filament).  I have a fog light bulb on my desk that I've examined under a 20 power magnifying glass and can't find a break in the wire or filament, yet it tests as an open circuit.  Stuff happens.

 

As for the pax side parking light--check fuse 8 (left and right parking and tail lights have their own fuses), and also check the ground--parking light assemblies ground via the mounting screws. 

 

mike

 

'69 Nevada sunroof-Wolfgang-bought new
'73 Sahara sunroof-Ludwig-since '78
'91 Brillantrot 318is sunroof-Georg Friederich 
Fiat Topolini (Benito & Luigi), Renault 4CVs (Anatole, Lucky Pierre, Brigette) & Kermit, the Bugeye Sprite

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More than you need, but here's the full details in case you want to do a deep dive/refurb on the wiring.  But Mike of course is already on the money for your specific questions: if it's just one high beam, it can only be a fault with the wire, connector, or filament for that side.

 

Edit: Just to add some confusion, squaretails indeed DO have both 'Low' and 'High' beam relays (probably explaining the lettering on yours), however the circuit is REALLY dumb, and they don't work like a 'normal' relay should.  In fact, the only purpose of the low beam relay is to turn OFF the low beams when the high beams are ON (with the highs off, the low beam relay is actually closed all the time, and the current for the low beams are just switched on/off with the light switch in the cabin; as I said, really dumb, but read my article above if you want to do it the 'right' way instead!)

Edited by AustrianVespaGuy
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Thanks Everyone! So I figured out the running lights issue.... an accidentally cut wire... I am dumb. 

 

For the high beam and low beam, still trying to figure that out. its odd because I've swapped the bulbs to each side and the bulbs are not the issue. the drivers high beam works and the passenger low beam does shut off when high beams turned on. just the high beam does not turn on....  @AustrianVespaGuy

 

Also, what bulbs do the turn signals use? I noticed that I have a dual filament bulb, but only one is in use for running lights and turn signals. Ex:

 9111157HP_L_702091c4-d23d-4895-bae4-2380

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22 minutes ago, bianchini said:

I noticed that I have a dual filament bulb, but only one is in use for running lights and turn signals.

The bulb you picture is in fact the correct bulb for your squarelight turn signal/parking light assembly.  The smaller and dimmer of the two filaments is your parking light, the larger/brighter filament is your turn signal.  If you're saying that only one filament is doing dual duty (stays on steadily for parking lights, blinks for turn signals) then there's something wrong. 

 

Check the bulb socket to make sure the two + contacts aren't touching, or that the bulb itself is defective (there's an internal short that allows the + sides of the two filament leads to touch), and then make sure the wires themselves aren't somehow touching.  If that's the case, it can cause all sorts of electrical gremlins in your parking/tail light circuit and your turn signals...

 

As for your recalcitrant high beam, if the bulb is good, then it's gotta be a hot (+) wire, or the plug that connects the headlamp to the car's wiring harness.  If it were a bad ground, then the low beam wouldn't work on that side.\

 

mike

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'69 Nevada sunroof-Wolfgang-bought new
'73 Sahara sunroof-Ludwig-since '78
'91 Brillantrot 318is sunroof-Georg Friederich 
Fiat Topolini (Benito & Luigi), Renault 4CVs (Anatole, Lucky Pierre, Brigette) & Kermit, the Bugeye Sprite

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21 hours ago, mike said:

As for your recalcitrant high beam, if the bulb is good, then it's gotta be a hot (+) wire, or the plug that connects the headlamp to the car's wiring harness.  If it were a bad ground, then the low beam wouldn't work on that side.\

Almost for sure the issue at this point. Try using a jumper wire from the fuse to the high beam + terminal and verify the light indeed comes on, then use your multimeter to check continuity along that white/purple wire that makes that same run (fuse to high beam), assuming that it's indeed open, then you need to start checking it for the possible break point or just run a new replacement wire.

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