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For some reason my horn has stopped working. There is no power going to the horn itself, and I have traced it back to the first plug near the relays at the front, still no power.

I have looked at the FSM and found that the Horn Relay is supposed to be in the Central Processing Unit (Page 15-8 body electrical system). Can you replace this relay?

If any one has come across this sort of thing can you let me know what fixed it.
Cheers.

Icemark

I rebuild the CPUs and have many in stock on my website.

But if you want to trouble shoot it yourself:

The horn relay is soldered into the main board of the CPU.

You should test the wire first before replacing or rebuilding the CPU.

First does the Green/white at the CPU in the main plug, (this is the big plug in the middle of the CPU) have 12volts on it all the time?

If no, you have a blown horn fuse.

If yes go to next step.

If you ground the green/orange in the main plug at the CPU does the horn work?

If yeso, then the problem is in the wiring between the steering column and the CPU or the switch or contacts are bad in the steering column.

If no... then when you ground that Grn/org does the green/red (in that same plug again) have 12volts+ on it?

If yes, the horns are bad, not the CPU.

If no, then the CPU is probably bad. Resolder or replace.

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Thanks Icemark.
I'll have a look tonight.

bejbis

if the relay for the horn is on the stock ECU then why does my horn work and i have a microtech and no stock ECU whatsoever? i havent screwed with the horn any since ive had the car.

-Daniel

Icemark

No the horn relay is in the CPU, not the ECU

Central Processing Unit= body computer
Emissions Control Unit= engine computer.

AcidShock

iTrader: (49)

Because the ECU and CPU are two different things.

EDIT: Lol, damn... too slow.

Flash

iTrader: (2)

All I know is that before I did extra grounding to the ECU, my horn didn't work. After the grounding, it works.

Icemark

Ahh yeah, okay

bejbis

cool icemark, thanks for the clarification.

-Daniel

Flash

iTrader: (2)

Hey, hence the "All I know". I know it doesn't make any sense. I swear I didn't kick the CPU either!

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Umm.. where is the Horn Fuse, I've checked the fuse cover and I can not find one that is just for the horn..

rx7will

iTrader: (6)

You could bypass the relay in the cpu by running your own. Thats what my friend did to my car, a lot easier than to resolder the cpu. Thats assuming that problem is the relay in the cpu.

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OK I found it. It was the fuse for the brake lights as well, it is labelled as STOP on the fuse box cover.. it's a 20 A fuse, just incase you where wondering..

Thanks for all your help guys.