Horn relay position on squarelights

[Mike Self]

Checked the archives and couldn't find a definitive answer; both my 02s are roundies so can't just look.  Squarelights have a rack for four relays--two are for headlights, one for the horn and the fourth position, usually empty on US cars, is for factory fog lights.  Front to back, which position is for which function?

 

TIA

mike

[Conserv]

Mike,

 

Not much help here, but I seem to recall the front-most relay being for the horn, while the second and third relays are for headlights.  (The ‘76 isn’t currently nearby.)  The rear-most slot was always empty from the factory (on U.S. cars).

 

Best regards,

 

Steve

 

Edited September 9, 2018 by Conserv

[Son of Marty]

And to make matters worse the wire harness will allow all 3 to be switched around, you'll probably need to put your hand on them as see which one clicks with the various functions.

[bluehills2002]

Mike, I cannot answer your question, but on my '74, which I believe to be fairly stock, the middle relay is of the square variety.  Perhaps that is the horn?

[worzella]

Hopefully this helps from my 75

[Conserv]

14 hours ago, bluehills2002 said:

Mike, I cannot answer your question, but on my '74, which I believe to be fairly stock, the middle relay is of the square variety.  Perhaps that is the horn?

 

The shape of the relay is not indicative of its use. All three, or four, of the relays are of the same capacity and, thus, fully interchangeable. I’d guess your middle relay has been replaced.

 

Regards,

 

Steve

 

 

[NYNick]

My 74Tii had 3 round relays. Nice to know they're interchangeable.

[Mike Self]

So....the rearmost relay is for the horn on all squarelights, correct?

 

mike

[HBChris]

Yes

[Conserv]

59 minutes ago, mike said:

So....the rearmost relay is for the horn on all squarelights, correct?

 

mike

 

Not on my '76, Mike. My lowbeams went out recently. I swapped the first and second relays, first being the front-most slot. Presto, my low beams came back and my horn would no longer work. This says to me that the horn was the first or second relay. But (a.) I find it hard to believe that BMW placed the horn relay between two headlight relays, and (2.) the horn relay occupied that inner fender spot long before the square taillight relay rack was invented; I'd think the horn relay thus had a sort of "engineering seniority" and would be placed first.  I could be wrong, but my horn was certainly in the first or second position and not in the third position. Given Son of Marty's note regarding ample wiring to permit placement of any plug in any position, I suppose there could be lots of variations 40+ years after the cars were assembled.

 

My '76 is 700 miles away, so I can't easily check this. There must be lots of other square taillights to triple check, quadruple check, quintuple check my thoughts.... ?

 

Best regards,

 

Steve

 

[John76]

On my '76, the front relay (#1) is the High Beam (white 87, green 30, brown 85 and white/blue 86 wires).

Second (#2) is the Low Beam (yellow 87, white/violet 85, green 86 and yellow/white 30 wires).

Third (#3) is Horn Relay (red/white 30&85, green/yellow 87, and brown/yellow 86 wires).

Last (#4) is the blank holder used for the Fog Light relay. 

 

 

 

[Conserv]

On 9/9/2018 at 8:39 PM, Son of Marty said:

And to make matters worse the wire harness will allow all 3 to be switched around, you'll probably need to put your hand on them as see which one clicks with the various functions.

 

So, were my ‘76’s relays removed and replaced in the wrong locations after one of my car’s “major” events, e.g., nosepiece replacement in 1978, repaint in 2015-2018?

 

I guess we’ll never know. So where do I go from here? Leave them the hell alone? Re-arrange them? 

 

Regards,

 

Steve

 

Edited September 11, 2018 by Conserv

[Son of Marty]

I don't know for sure, or even if the factory went out of their way to put them in order Ive just seen them out of order. 

[Mike Self]

Maybe the position of the relays depended on how much beer Hans for Fritz or Franz had for lunch that day...

 

mike

[jimk]

10 hours ago, Conserv said:

I guess we’ll never know. So where do I go from here? Leave them the hell alone? Re-arrange them? 

If the shoe fits, wear it.