PCM/BCM/TCM pinout needed?

2009 MAZDA 6

156,000 MILES • 3.7L • 6 CYL • 2WD • AUTOMATIC

PANDAMONIC

MEMBER
1 POST

Bad ECM. Misfire on #4 changed coil because it melted, and it did it again. I tested the line going to that specific coil and the PCM continuously kept on sending voltage to it nonstop.

Jul 25, 2023 at 11:49 AM

STEVE W.

✓ASE Certified Mechanic
15,200 POSTS

Constant 12 volts to the violet wire that connects the coils is normal. The ECU controls the coils by turning the ground to each coil on and off. In your case it sounds like the driver transistor that is supposed to control #4 has shorted and is holding the ground on or the control wire (green w/violet stripe) has shorted. I would start by following the harness from the injector and be sure that it hasn't rubbed through and grounded out that way. Next go to the PCM and find the same wire at terminal 2AX There will be a short connector harness with a white wire w/green stripe that you should be able to disconnect. Then test the wire that goes to the coil with a meter set to ohms. If the wire now shows open circuit when tested and unplugged at both ends the PCM driver is likely the culprit, it's actually common for them to short and a burnt coil is the result.

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Jul 26, 2023 at 6:55 AM

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