ECM appears to be defective?
The wiring harnesses on the Mazda 2008 RX8s include a shielded 2
conductor branch for the ESS signal lines. The shielded leads are paired for
conduction of the ESS generated signal to the ECM. The reasoning for the
shielding and pairing are understood.
Oddly, we have encountered 2 ECMs both of which, when measured, have
one of the 2 input signal pins shorted to ground. ???
The resulting non-isolated input allows electrical noise to improperly
influence the ignition/injection triggering data. i.e. Hash from the ignition can
sometimes cause problems at idle. And, arching from the starter brushes,
sometimes will disrupt ignition altogether, preventing engine startup.
Is this a design/manufacturing flaw, or have we encountered 2 ECMs with
The 2 ECM inputs from the ESS are 2U and 2X. The shield connects to 2H.
In our case, we have encountered 2 ECM with pins 2X and 2H shorted
together. We have a work-around but do NOT want to employ it on a
Are both of these ECMs defective does MAZDA a reason for tying 2X and
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