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.
Flash Electrically Erasable Programmable Read Only Memory (EEPROM): Description
Flash electrically erasable programmable read only memory (EEPROM) is contained in an integrated circuit internal to the PCM and TCM. The EEPROM contains the vehicle strategy including calibration information specific to the vehicle and is capable of being reprogrammed.
As part of the calibration there is an area referred to as the vehicle identification (VID) block in the PCM and the transmission identification (TRID) block in the TCM. Program the VID block when installing a new PCM as described under Programming the VID Block for a Replacement PCM, and program the TRID block as described under Programming the TRID Block for a Replacement TCM. Failure to carry out these procedures may generate diagnostic trouble codes (DTCs). The VID and TRID blocks in an existing PCM or TCM can also be tailored to accommodate various hardware changes made to the vehicle since production. Failure to carry out these procedures correctly may generate DTCs. The VID and TRID blocks contain many items used by the strategy for a variety of functions. Some of these items include the vehicle identification number (VIN), octane adjust, fuel octane, fuel type, vehicle speed limit, tire size, axle ratio, generator and traction motor resolver offsets, and the presence of speed control. Only items applicable to vehicle hardware and supported by the VID and TRID blocks are displayed on the scan tool.
When changing items in the VID or TRID blocks, the strategy places range limits on certain items such as tire and axle ratio. The VID and TRID blocks are also limited to the number of times they can be reconfigured. When this limit is reached, the scan tool displays a message indicating the need to flash the PCM or TCM again to reset the VID or TRID blocks.
Reprogramming can be carried out by a local Ford dealer or any non-Ford facility. Refer to the manufacturer's user manual for details.
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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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