The stock wiring is getting old and brittle.  This leads to corrosion of the wires and connections, and the possibility of the wires failing internally!  This can lead to countless headaches trying to diagnose electrical problems.  We recommend using the Mazda service manual and using the input/output table in section 4B to spec all wires going in and out of the stock ECU.

Wires that most likely fail are those that run along side the passenger strut tower in the engine bay.  Due to the close proximity of the stock turbocharger, the increased heat of the turbo just accelerates wear and damage on the wires in this location.

Another source of problems for the engine wiring harness is right behind the alternator.  There is a retaining nut for the alternator that has a built-in clamp that secures the engine wiring harness.  The clamp will sometimes get loose and rub against the engine wiring harness running beneath it.  If the clamp rubs through the engine wiring harness, it will cause a short circuit.

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