95 SHO Horn issue

[mannyjfk]

The horn in my car only works when the car is off. As soon as I put the key in the ignition it wont work. Is driving me out of my sockets not having a horn in NYC.

Please help...

[shorod]

Interestingly, the horn circuit is different for the SHO from the other Taurus models. The horn relay gets power from fuse 12 in the instrument panel fuse panel (20-ampere), but the ground comes pressing the horn buttons which close a contact to the PCM (3.0L SHO) or the cruise control servo (3.2L SHO) through the clocksprings in the steering column. For the regular Taurus, the other end of the clockspring is connected to ground directly. Alternatively, the ground can be completed by a discrete from the remote keyless entry module.

Is your SHO the auto or the manual transmission? If the auto, it would be interesting to know if your cruise shuts off when the horn button is pressed. If so, you know the clockspring is good. If the cruise doesn't work and you have the auto, you should check the black wire at the cruise control servo assembly for voltage potential with the key off and with the key on.

-Rod

[mannyjfk]

You must know a lot about SHO. I have the auto tranny and the cruise control dont work. I didnt miss that because I dont use it at all. Any advise?

[shorod]

Since you have the auto, it sounds like the cruise not working may be related to the horn not working since the horn gets its ground through the cruise servo. Very odd design, I don't understand it. I'll have to look at the wiring diagram for the horn again. You may be able to just provide a good ground to the horn wire at the cruise servo to see if that gets your horn working since you don't use the cruise anyway.

-Rod

[mannyjfk]

I will be waiting for any info you can provide.

Thanks in advance.

Manny

[shorod]

First, check fuse 6 (15-ampere) in the instrument panel fuse panel. This fuse provides power to the cruise servo when the key is in ACC or Run. If this fuse is good, then check fuse 1 (15-amp) in the same fuse panel. It has power all the time and also provides power to the cruise servo.

If at the moment you aren't concerned with getting the cruise working, I'd suggest you take the orange wire in terminal location 6 at the speed control servo/amplifier assembly and connect it directly to ground. See if that gets your horn working properly with the key on or off.

-Rod

[mannyjfk]

My mind started to take shape now but I have no clue as of where to find the servo in the car. Any ideas? can you point me the right way?

[shorod]

Oh boy, it's been quite some time since I had my '93 SHO. It's probably mounted near one of the strut towers, there will be a wire harness plugged in to one end and the other end will have a sheathed cable exiting from it. That cable will continue to the throttle plate. Your best bet may be to start at the throttle plate, then follow the two cables attached to it. One will go into the firewall for the accelerator pedal. That's not the one you want. The other one will continue to the cruise control servo.

-Rod

[shorod]

From the service manual, it looks like the cruise control servo/amplifier assembly is located on the lower left hand side of the engine compartment. Maybe mounted to the strut tower slightly below the brake master cylinder.

-Rod

[tripletdaddy]

Rod, are you sure that the orange wire should provide a ground to the horn and cc setting switches? I have a diagram showing an orange wire going to them in the steering wheel, but it is the hot side. This may not be the same cc. The servo is vacuum operated and has a three wire feed. It appears to be o/y grnd as is the eca is o/y grnd. On newer Fords I see they use an eight wire fed servo with tan/org as gnrd to the switches and horn.

[shorod]

I'm going off the diagram for the speed control for a 1995 Taurus SHO 3.2L from the Factory Service Manual. That's as sure as I can get without having the car in front of me. There are slight differences between the non-SHO, the 3.0L SHO, and the 3.2L SHO. In the 3.2L diagram, there is a horn relay. One side of the relay coil is tied to power (hot). The other side of the relay coil travels through a clockspring, to the momentary horn switches. When closed, the horn switches ground through another clock spring to the cruise servo as an orange wire. At the cruise servo, the orange wire in the diagram is labeled, "Control Switch Ground."

-Rod

[tripletdaddy]

Rod, I only brought that up to cause problems. Or was I trying to prevent one? Since you said to ground the orange wire and it was hot in one of my pathetic diagrams, I didn't want Mannyjfk to have an unexpected fireshow or burnt fuse. Just trying to be helpful. I can't wait to get those Real wiring diagrams. What kills me, is Ford doesn't follow any wiring color standardization, so you have to learn everything every time and cannot assume anything for every car, every year, every body style, every version, every whatever!?! It is true that different models will share some similar wiring systems, but they DON'T have the same wire colors!?! Urrrr! Case in point, the 95 Taurus SHO here has a different horn and CC arrangement than the plain old 95 Taurus, but the 95 Windstar has the same exact system as the SHO, just with different colored wires. WTHF???!!! Do you know Rod? You got the degree for this sort of stuff. I didn't study things that you can't see.

[shorod]

I wish I had answers for you. Well, I guess I have one. You should see those real wiring diagrams soon.

At least the domestic brands are now pretty good about maintaining wire colors through the circuit. When I was installing car alarms for a hobby back in the high school years, I was stumbling across a lot of parking light circuits that would use one color wire at one end of the circuit, but by the time it made it though one or two connectors, the wire color had changed. That drove me batty. The first Toyota I did an install on, I was amazed to find the wire color remained consistent through the circuit!

From the programs I've worked on (professionally) we keep wire colors the same in interconnects, the few times that we use discrete wires anymore. Most of our interconnects have gone to printed flex cables. What hasn't been so good is following through on naming convention. That's about as bad a wiring color, the line is called one thing at the originating circuit card, but each card designer modifies the name slightly and the systems engineers don't explain to the card designers that that's a problem or correct it. I started out as a systems engineer, so I can't say a whole lot as I was probably guilty of it too.

I've also learned on the job that letting the magic smoke out is a bad thing. That usually causes things to stop working. So, I don't fault anyone (depending on my mood) for second-guessing me.

-Rod

[tripletdaddy]

Originally Posted by shorod

I've also learned on the job that letting the magic smoke out is a bad thing. That usually causes things to stop working. So, I don't fault anyone (depending on my mood) for second-guessing me.

-Rod

Magic smoke? Is that anything like the ground fault fairy? You must mean "having problems with your shorts."

Changing wire colors from connector to connector is dirty pool and down right spiteful and deceptive. What were they thinking!? Can we blame a EE for this? In their defense, I bet it was a business decision to further the manufacturer's opportunities to have service work, since no one would want to work on it. (I always like to blame the nonengineer business types for making the cost cutting, etc., design decisions that make engineers look bad. ) I remember working on my 76 Ford Custom 500 woring (oops, I'll leave that there) and found they did that randomly changing wire color crap from connector to connector to component then. You had to have a clear head to work on it, that's for sure.

So, any memos circulate on getting everyone on the same page on component ids? Sounds like the classic telephone game. You wouldn't know that what was at the end had anything to do with the beginning, because the words had changed so much inbetween from person to person. "Uh, is schem. 1a and 1g for different systems? Here we have the wiring for a can opener and here we have a RCPS (rotational cylinder perimeter dissector)?"