HORN RELAY

[Rich]

Hi folks, does any one have a suggestion for a new replacement for this old horn relay, I can not find a used one so trying the new route, thank you, Richard

[JohnS]

OPEL KADETT ORIGINAL GERMAN MADE HELLA HORN RELAY

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Is this what your one looks like?  This one has three poles labelled 85, 87 & 30/51.  Hope that helps

 

I think 85 = ground

87 power to horn

30/51 power

Part # 91/6-11-12V

12 volt

Edited March 28, 2023 by JohnS

[JohnS]

or any simple relay could work in a pinch for cheap...  Search Hella or Bosch horn or starter relay...

 

 

 

Edited March 28, 2023 by JohnS

[John76]

2 hours ago, JohnS said:

the old style canister ones are grounded through the body of the relay (hence only three pins). 

 

The 3-prong relays are wired as follows:

 

30/51   Power source (+12V) switched or always hot. 

 

87        Load (horn). connect to horn (+). 

            If horn has 2 tabs connect (-) to ground, otherwise horn is grounded through the mounting bolt.

 

85        To horn button (grounds for "honk")

 

PS: You might want to open the relay and clean the contact or resolder any broken coil wires... worth a try for a $55 Hella relay!

Or, as suggested, replace with a 4-prong Tyco (Bosch) relay for $15.

[JohnS]

@John76 I knew you would come through with the correct edumication   Thanks.  

 

[Mike Self]

That same relay was used on a bunch of German cars of the same vintage, like M-B and Porsche; also was the overdrive relay on Volvo P1800s, and early 240 series Volvo sedans.  Might find one of those in a salvage yard.  

 

And as John mentioned, you can carefully bend the crimped aluminum cover back to reveal the innards; so long as the coil isn't all burned looking, the problem is probably burned or dirty contact points, easily cleaned with an ignition file or a doubled over piece of fine grit sandpaper.  I've salvaged several that way.

 

mike

[Rich]

thank you guys so much, great info, off to the work bench Batman, 

[John76]

16 hours ago, John76 said:

85        To horn button (grounds for "honk")

Correction !!!

 

My previous post was WRONG concerning the #85 tab on a 3-prong relay.

The mounting tab for the relay completes the coil ground and is always grounded.

The #85 tab is ENERGIZED with +12v when the horn is honked. 

Sorry... this is the opposite of how the horn works on a square-tail. 

The top relay illustration (attached) shows a 4-pin relay. The 3-pin has the #86 tab internally grounded to the mounting.

 

 

[visionaut]

Most excellent, John..

[JohnS]

I purchased one of those new Hella horn relays from ebay only to realize that it only has three pins vs. the 4 pins on my original horn relay.  I found a good substitute for the old round one though.  I used an old square style BOSCH 0 332 003 017 relay instead.  It has the same mounting as the original round one.  It's the same as used to bypass the ballast resistor on my '73.  Wanted to be safe so used the square 4 pin style (actually 5 pin because it has the dual 87 outputs).  Could the three pin one be used on a car that expects the 4 pins?  If so, how would you wire it?  New square one works great and mounts to the original holes.  Thanks,

John

 

 

Edited May 23, 2023 by JohnS

[John76]

18 minutes ago, JohnS said:

Could the three pin one be used on a car that expects the 4 pins? 

Yes ... but you might need to reconfigure the plug.

On a three-pin relay:

30/51 = +12V power (fuse protected)

87      = Load (horn(s))

85      = + 12V trigger source

The mounting tabs on the relay provide the path to ground.  Brown wire in the 4-pin plug is not needed.

Note: I believe the earlier cars (pre-square) used the horn button to energize the relay (#85) with +12V. The later cars used the horn button to ground the relay.

[JohnS]

It's hip to be square so will use the square one.  Anyone out there with an early car looking for a nice NOS 3 - pole horn relay, hit me up.  I'll make a deal better than even Deal'n Dave 😁

Edited May 23, 2023 by JohnS

[Rich]

OK John S, so I got to ask, how much for the NOS 3 pole horn relay, please, and it would replace this one pictured, ? This past weekend I just replaced the voltage regulator and re did some of the wiring. 

[JohnS]

2 hours ago, Rich said:

OK John S, so I got to ask, how much for the NOS 3 pole horn relay, please, and it would replace this one pictured, ? This past weekend I just replaced the voltage regulator and re did some of the wiring. 

 

 

Hi Rich,

  I couldn't get the three pole relay to work on my '73.  I tried as John76 suggested with switching the wiring, but it didn't work and I just swapped back to the 4-pole relay which matches my original wiring.  I think you also have a 4-pole relay on your car, so that's what you need, not the 3-pole one.  The square one that I found on ebay was oddly enough original equipment on Polaris Snowmobiles back in the day it seems.  Weird.  Got it from some guy up in Minnesota (Blunt land).  You can find them on ebay.  But $$'s 😒

 

https://www.ebay.com/itm/165858301843

Edited May 24, 2023 by JohnS

[Rich]

thanks so ,much, all the best, enjoy driving season, Rich