i have an 86 non turbo : ( with its fair share of electrical problems does anybody know how to get a horn reworkin need walkthrough info to fixin it pls help greatly appreciated

 

Push it when you don't NEED to use it. That is the only time I remember mine working.

 

You would need to determine if the switch is bad, the CPU is bad or the Horn is bad in order to know what to fix

 

mine (86gxl) has the same problem. only works if it has been sitting in the sun in my drive. It gets damn hot inside and my horn and idiot lights work seatbelt chime etc work perfect. once car cools off they all stop working. (my idiot light cluster is an Icemark rebuild and the lights work EXCEPT when I turn key on unless car inside is HOT)
I guess it is CPU related. What needs to be done in this case???
The horn and switch are good is my point

 

yep, CPU

 

Okay,
Is there a fix/repair for the existing CPU?
If no fix then what about getting a replacment, rebuilt one???

Sorry for hijacking this thread but it appears we share the same problem

 

Yes, you can either try rebuilding it yourself, or I can do it for you.

To rebuild it yourself, you will want to remove and replace all the solder on the main CPU board where the plug, pluggs into. Then flow new solder in. I also replace the relays if they look burnt, you may or may not need to do this.

Or you can send it in, and I can do it for you.

If you don't want to be without the turn signals and brake lights, just send the main board and leave the two bottom boards plugged in (however that requires dis-assembly of the CPU).

I also do have some already rebuilt ones in stock.

 

Gotta go find/pull the cpu. I`ll post back after finishing.
Thanks Mark,

Scott

 

Hey Icemark,

Do I need to remove the Epoxy/Varnish coating on the CPU board?
If yes then what will get the stuff off?
Or can I just work "through" it with out any problem?

 

Icemark\
WeI got the cpu resoldered and back in the car. For the first time since I got the car the cluster lightd work and so does the horn

 

You can burn through it. I do recommend a thin coat of clear paint or conformal coating though, after you have removed and replaced the solder.

 

This is my setup. I had the same problem on my 86 GXL.

I just wired up a new circuit for my horns.

I used some spare horns off my 240 since the RX-7 horns were rusted up pretty bad.

Take a wire (with a fuse) directly from the battery to the "screwy" part of the horns. Make sure you mount the horns on plastic and that no metal is in the area or it will short circuit and blow your fuse. If you have no fuse prepare for an electrical fire! Use a fuse! Next you'll need to take off the steering wheel cover and study the wires coming to and from the horn button. The basic idea here is that the steering column is a ground wire. You'll want to connect the OUTPUT wire from the horn button the the prongs on the horns. THEN take a 6-7 foot spare wire and run it from the OUTPUT of the horn button to the prongs on the horns. Should work great.

Sooo...

1. POSITIVE (+) from battery to screw on horns (mount on plastic) (Use a 15-30 amp fuse)
2. remove steering wheel cover
3. connect OUTPUT wire from horn button to the prongs on the horns (route 6-7 feet of 16 guage wire through the fender and engine bay to the horns.

 

NO, NO> NO

The factory switch in the steering column is rated for only 5 amps maximum. You must use a relay (just like the CPU does).

Wiring the horn direct to the horn switch, is just asking to burn the horn switch out. If you lay on the horn for anything but a brief moment you will burn out the switch or contacts in the steering column!

If you wanted to do some sort of NON CPU useage, you need at very least a relay which would wire as follows:

Horn wire from steering column to 85 of the relay
Fused 12 volts battery to 86 and 87 of the relay
30 of the relay to the Horn wire coming out of the CPU (you don't want to run extra wires).

But fixing the CPU is the best bet.

 

It's better then no horn at all I guess. I haven't had any problems with it so far. BTW I have an s5 steering wheel if that makes any difference. Is there some sort of "resistor" I can get to reduce the current to 5-10 amps? It doesn't spark when you touch the contacts together so I figured it was fine.

I just went ahead and did this to mine because the whole system was no good. Everything was rusted. The relays were blown. I think the CPU may be damaged as well because the left turn signal blinks rapidly and I've checked all the bulbs. It blinks even faster when you flip the lights on.

 

until you weld the steering wheel into position no, the contacts are the same regardless of series , You are too lame to buy a $5 relay from radioshack, but not too lame to buy a resistor??? Anyway, no you can;t use a resistor unless you wish for the horn to be less loud and the size of resistor needed would cost more than a relay anyway not nessesarly the correct way to determine a load.
The turn signal board in the CPU is a different board than the Horn relay is on. Fast flash indicates a bad bulb, bad bulb socket, or short in the wiring. if the turn signal board in the CPU is bad on the outputs it too could be bad or damaged, but simply re-soldering the board connections and replacing the relays should solve that.

You never want to just wire past things like you did. Almost none of the switches on the FC are capable of driving that much load. Always use a relay or the correct part.

 

I didn't want to mess with hunting down an entire CPU and electrical system so I rigged it up the old fashioned way. I didn't want to spend any money on something I was going to use once every couple months for 2 seconds. I know there's a right way to do it and that my way is a last resort method but I just don't want to mess with it anymore. Basically my method works but it's not the best way to do it obviously. It would lighten the load a bit to use just one horn too I'm sure.

 

Sorry, guy but you really need to sell your 7.
I fixed the problem with less than an hours worth of work.
What you are recommending is just a hack job. Anything worth doing is worth doing right. Hate to see how you would handle the REALLY tough ****

 

As previously mentioned, resoldering the CPU usually does the trick, and may fix a few other things.

It is outlined in the page below. Need a ratchet w/ 10mm socket with extension, a pair of needle-nose pliars, patience, a small screwdriver and a soldering iron.
http://www.teamfc3s.org/faq/index.shtml

I had fixed my horn this way in order to pass safety inspection.

when I took my CPU out and looked at the back on the circuit board, almost all of the large solder joints were cracked. Just heated up my iron and resoldered them.
BEWARE OLD SOLDER SMELLS FUNNY. DO NOT BREATHE DEEP.

Reversed the removal instructions... then

BEEP BEEP!!!

 

Running horns directly through a low-current switch is not the old fashioned way, it's the dodgy way that will eventually fry the switch. The CPU can be easily and safely bypassed with an external relay if you can't be bothered repairing it.

People come here looking for help on fixing their cars, not wrecking them. Please keep advice like this to yourself.