Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Plus 4 GDI: second horn

My 2018 Plus 4 has one factory fitted horn; but the cable tree offers the connection of a second horn. But when I connect two horns at the same time (with the two factory fitted connections), I can't get them to work properly, they just make weak sort-of-honking sound. Any ideas? Is an additional relay required?

No. You have a bad connection or faulty horn drawing too much current.

Please check if horns are a matched pair. You should typically have a high and a low note one although not relevant to issue. Check each horn individually in each location, noting that second horns connectors will have suffered corrosion whilst not in use. Note also that cables light green/white are permanently live via fuse 6, 10 amps, so you could check it's seated properly. The other purple/black ones are the switched ground connection via horn push. Check all is well there including cleaning slip ring with wheel off. Although it was obviously adequate for one horn, a dirty contact may add enough resistance to limit volts with current draw from both horns.

Although you didn't mention, if you have bought a pair of very loud after market horns they will draw extra current so a relay may be necessary and an increase in fuse size to match. The instructions should explain. This is certainly the case with air horns. Don't fit supplied relays always use quality diode protected ones.

Richard is spot on with above.

You could also bench rest the additional horn by powering it (off the car) with a battery charger or the like, sometimes if not used for long periods they 'stick' so give it a sharp tap as you apply juice

When I did this mod, I bought a pair of Fiamm horns. No problems encountered other than one of the pre installed wires was a bit on the short side for my car. A short extension fixed that.

Worked for me too, just plug and play

Fiamm for me, no problems.

You're making me want new horns.

Me too. For the wires as well.

I made one little mistake though.

I fitted the horns with the opening facing forward. I was thinking that that would project the sound better.

2 days later I drove through standing storm water in a railway underpass. It was like driving unde a waterfall

15 minutes later I thought to try the nice new FIAMM horns. All that was projected was a vague gurgle.

The never recovered and in the end I fitted the original and a matched horn from the same manufacturer as the original.

Moral of the story: don't point them forward or they might become water scoops.

PS. FIAMM is correctly written in upper case because it stands for "Fabbrica Italiana Accumulatori Motocarri Montecchio" (originally a battery manufacturer before diversifying into horns - of course they still make batteries too). The upper case FIAMM is retained for historical reasons.

Strictly speaking the same applies to FIAT, acronym for "Fabbrica Italiana Automobili Torino" though by common use "Fiat" has now become a name in its own right and even the company itself uses it in both forms

Red horns?

I‘ve got a set of BOSCH horns, resting a long time at the dealers shelf.

They need a relais. A fitting instruction was also in the box.

Greets René

Ich habe ein Set BOSCH „Doppelhupen“ aus einem älteren Händlerbestand.

Für die Hörner benötigt man ausdrücklich ein Relais, in der Montageanleitung ist das auch genau spezifiziert.

Gruß René

NS: wie vorher geschrieben bin ich mir über den Einbauort nicht im klaren. Am Originalplatz nicht sinnvoll, im Kühlergrill werden die im Regen geflutet… daher liegen die bei mir weiter im Regal.