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'07 Exige S
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Hi guys,
So I fell prey to the infamous stalling problem after I wired in the Nautilus Air Horn according to the recommended wiring instructions (didnt happen on my Elise!!!)
I found this guys post outlining a different way to wire the relay and horn that supposedly fixes/eliminates the stalling problem.

He says the following:

The OEM horn's purple wire goes to terminal 86
The OEM horn's black wire (ground - he says brown) goes to terminal 85
Power from the battery post up front goes directly to the positive terminal on the horn
Ground from the horn goes to the chassis

But he does not mention what is wired to terminal 30 and terminal 87 on the relay.
Did he mean power from the battery must connect to terminal 30 and then from terminal 87 to the horn?

Can someone please help me? Thanks. Henry
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This posting is about completing a trouble-free Stebel installation in an Exige by using a relay and the least amount of new wiring as possible. There are many Stebel postings with lots of pictures, but those postings do not provide solutions to a quirk that seems to affect Exiges when routing new wiring across the scuttle area in the installation. :panic:

A couple of Exige owners (Doghouse and I) have experienced engine cut-out when honking the horn after installing a Stebel using a relay and (+) and (-) wires connected the Stebel to the Exige remote battery terminals. It seems the that certain wiring set-ups can cause electrical interference in the scuttle area beneath the service panels, which leads to engine cut-out.

Credit goes to Doghouse and TheViper for helping out. I am not an electrical expert, but I solved the cut-out issue because of their tips and by using a process of elimination to isolate the problem.

There have been many discussions about not needing to use a relay (see other Stebel posts), but the purpose of this post is to address using a relay in an Exige installation. Sourcing power for the relay in an Elise is a PITA, whereas it is a no-brainer in an Exige because of the remote battery posts in the scuttle area under the driver's service panel.

In this wiring, the OEM horn wires are used to activate the relay mechanism, and the Stebel uses 12 gauge power and ground wires. This wiring set-up will prevent horn wiring damage or possibly fire from the horn wires overheating, because the Stebel draws a lot more amperage than the OEM horn circuit is designed for.

Wiring:
- The OEM horn's positive wire (purple and brown) is attached to relay terminal 86, which I wired as the (+) side of the relay coil circuit. I made a wire extension to reach the Stebel.

- The OEM horn's ground wire (brown) is attached to relay terminal 85, which I wired as the (-) side of the relay coil circuit. Again, I made a wire extension to reach the Stebel and wrapped both (+) and (-) wires in wire / cable cover. See picture below.

- The Stebel's (+) terminal is wired to the Exige's (+) remote battery terminal using 12 gauge wire and a 20 amp fuse just before the terminal connection. This power wire is in a plastic cable cover that is routed through the radiator hose opening in the passenger side wheel well, up and across the scuttle area toward the driver's side, behind the brake booster and up to the (+) battery terminal. Route it around (away from) the main wiring harness. See picture below.

- The Stebel's (-) terminal is grounded to the chassis using 12 gauge wire fastened to the chassis (with a stainless steel fastener) using an existing fabrication hole drilled by the factory. This ground wire is about 8 inches long. See picture below.

Pressing the horn button cause the relay coil circuit at terminals 85 and 86 to close thereby bridging terminals 30 and 87 and sending power to the horn.
 

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