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.
Circuit Description
The microprocessor contains a data storage area (keep alive memory) which can save pertinent data when ignition is turned off. Keep Alive Memory (KAM) data is lost if battery power or module ground is removed from module. KAM area is an integral part of microprocessor and cannot be serviced separately.
The microprocessor calculates a checksum on those areas of memory that hold critical operation data. This is done at a regular interval and is called periodic checksum. The microprocessor also calculates a checksum on these memory locations when ever new data is written to them. This is called running checksum. To check KAM, the microprocessor compares periodic checksum to running checksum. If they do not match, the microprocessor sets DTC.
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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.