Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Powertrain Control Module (Pcm) Removal / Installation: Notes
- PCM Programming, Vehicle Identification (VID) Block and "As Built Data" for a Replacement PCM: A new PCM will contain the latest strategy and calibration level for a particular vehicle. However, the VID block will be blank and will need programming. There are two procedures available: the first is an automatic data transfer from the old PCM to the new PCM and the second is "As Built Data" or manual data entry into the new PCM:
Once keep alive random access memory (RAM) has been reset, the engine must idle for 15 minutes (actual time varies between strategies) to learn new idle air trim values
- Automatic data transfer is performed if the old PCM is capable of communicating. This is done by the use of a scan tool to retrieve data from the old PCM before removing it from the vehicle.
The stored data can now be downloaded to the new PCM after it has been replaced.
- "As built data" or manual data entry, must be performed if the old PCM is damaged and/or incapable of communicating. Remove and replace the old PCM. Using a compatible scan tool, select and execute module/parameter reprogramming, referring to the manufacturer user manual . Make certain that all parameters are included:
- Failure to properly program tire size in revolutions per mile, (rev/mile = 63,360 divided by the tire circumference in inches) axle ratio, axle size, anti-lock brake system (ABS) (4WBS or RWABS) 4WD/2WD, and/or manual / electronic shift on the fly (MSOF/ESOF) may result in DTCs P1635, P1639.
- You will need the "as built data" to perform this procedure. If you are unable to obtain "as built data" from Mazda's Electronic Service Information website, you will need to contact the Mazda Technical Assistance Hotline.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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