P1605moderate severityPowertrain
PCM Keep Alive Memory Test Error
on 2003 Mazda B2300 2.3L I4 · FWD
What this code means
The PCM Keep Alive Memory self-test has detected an error. The PCM cannot properly store or retrieve adaptive learning values from its internal memory.
Symptoms
- Check Engine Light
- PCM defaults to base calibration
- Rough idle initially after restart
- Harsh transmission shifts
Common causes
- KAM circuit voltage intermittent
- Faulty KAM fuse or relay
- PCM internal memory failure
- Battery cable providing unstable voltage
Diagnostic steps
- Check KAM fuse and relay
- Test KAM circuit voltage at PCM connector
- Check battery and alternator output
- Clear code and retest; if recurring, suspect PCM failure
Repair notes
Check the KAM circuit power supply; replace the PCM if internal memory has failed.
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