Need help tracing my partially missing horn wiring.

ulrichd · 12-03-2007, 01:13 PM

Car is a 70T with missing 6-pin relay connector and horn relay. I checked the horn against the battery and it works - that's the extend of my electrical expertise.

Pic1: Pos and neg wires out of the horn (black/green and mauve) together with headlight wires go to an opening in the inner fender. Terminates into a plug in the front trunk shown in Pic2.

Pic2: I don't see the same horn color wires coming out of the plug so I can't really trace them to the fuse box. There is a black/green wire but different pattern and no mauve wire.

Pic3: Where my horn pin connector and relay should be.

So would both wires go to a fuse and then a wire goes from the fuse to the pin connector? And the wire from the steering column would also go to the pin connector. I have looked at a wiring diagram for my car but it's like greek to me.

I can't get the car inspected without the horn working.

Any help at all would be very much appreciated.

Ulrich

ulrichd · 12-03-2007, 01:36 PM

Maybe someone can help talk me through this with the help of this diagram. Where are the relays?

Ulrich

Rich Lambert · Rich Lambert's Garage

First off, the schematic you're showing isn't the '70T schematic in the factory manual. That's the 911S and E schematic.

Per the factory manual:
Let's assume by black-green, you mean black-yellow (B-Y) and by mauve, you mean brown (BR)...all grounds on the car are brown.

One horn will have (2) B-Y wires on one terminal and (2) BR wires on the other terminal. The other horn will have (1) B-Y wire that comes from the 1st horn and (1) BR wire that comes from the 1st horn.

The other B-Y wire on the 1st horn goes into the round connector and then to term# 87 on the horn relay. The other BR wire on the the 1st horn goes to the ground connector which is separate from the connector the B-Y goes into (that's why you don't see the same wires coming out). The horn relay also has a brown-white (BR-W) at term# 85 that goes to another ground connector and a pair of red (R) wires at term# 30, one of which jumpers to term# 86 of the relay. The other R wire goes to fuse# 2 (term 87a of the relay is empty).

Bottom line...without a horn relay or that connector, the horns aren't going to work. What happened to the connector?

Pick up a relay and a connector and I can walk you through the hook-up and troubleshooting process, providing you have a multimeter and some rudimentary knowledge as to how to use it. It's really not hard. It's just like following a road map.

ulrichd · 12-03-2007, 03:22 PM

Thank you Rich. I think the relay diagram below is correct. I will get a new socket, relay and with your info above I should be able to take a shot at this.

Ulrich

ulrichd · 12-03-2007, 03:43 PM

One more question. I can get a new relay socket and horn relay from Pelican but they won't have the relay number markings as shown on the diagram (30, 85, 87, 87a,etc.). Will that matter?

Ulrich

ulrichd · 12-03-2007, 03:56 PM

Just noticed this mounted above the fuse boxes. The wire colors would suggest some kind of non OEM horn relay fix? This would explain the missing relay socket.
Anyone know what this is?

Ulrich

Rich Lambert · Rich Lambert's Garage

Does that relay click when you push the horn button? Is the little horn plunger switch present in the steering column (is it split in half?). Sometimes people take those out when the rubber collar gets deformed and the horn starts honking every time the car goes around a corner.

Some relays will have a little schematic on the relay body. If yours does, post what it says. Or, if there's numbers next to the terminals where the wires are attached, sometimes you can figure out how the relay functions from that.