111 Horn wiring

[ctaylor738]

I'm working on a 1965 111.023 220SE cabriolet, trying to get the horns to work without a wiring diagram.

Does the horn wiring use a relay, and if so, where is it located?  The fuse labeling for F2 says "horn and relay" but the EPC doesn't show a horn relay.  There are three relays on the firewall.

- black "can" like the hot start relay on the 230SL
- black 5-pin
- silver 4-pin

None of these have the wire colors that run to the horns.

TIA.

[114015]

Hello Chuck,


The wiring of those contemporary Mercedes cars is pretty much the same  - with the exceptions of the set-ups that each single car series had,
e.g. diesels versus gasoline or carburettor vs. fuel injection, etc.

Thus, the horn wiring is pretty much all the same with our cars.
The horns are directly connected from the fuse box with a black-pink-yellow (bl-rs-ye) thick wire and receive ground by the horn contact on/under the steering wheel.

There is no relay for the horn honking functions.
The relays you mentioned are (more or less) all for the fuel injection system.

Details on this to be found in the BBB Passenger cars 1959 onwards.

Regards,
Achim

[ctaylor738]

Very odd.  Here's a picture of the fuse list.  So it's the usual arrangement, constant hot to the horns and ground supplied by the contacts under the horn ring?

[ctaylor738]

Closing this out.  Removed the steering wheel and horn ring and found that the brown (ground) wire had been disconnected and neatly taped.  I took this as a bad sign but I re-connected it and the horns now work. 

[wwheeler]

By constant hot, do you mean that the horn always blows key or not? My '68 W111 requires the key to be in #1 position in order for the horns to work.

[ja17]

The horns themselves are supplied with positive 12 volts when the ignition is on. They do not activate because they still lack negative (earth). The horns activate when the horn ring is depressed and the ground (earth) is supplied to the horns. I believe the reasoning for this is the fact that the metal horn ring might  conduct a 12 volt shock to the driver if the column horn ring switch was wired (positive 12 volt). The steering column contacts are very robust and need no relay and safely send negative (earth) directly to the horns.

[114015]

(That's what I meant - and what Joe confirmed....)