P1600 ECM Battery Backup (BATT) Malfunction
What does P1600 mean on a Toyota?
P1600 — ECM Battery Backup (BATT) Malfunction. This Toyota-enhanced code applies to Camry, Corolla, RAV4, Tacoma (all OBD-II Toyotas).
Common causes of P1600
- Blown ECM BATT fuse
- Recent battery disconnect clearing adaptations
- Corroded battery terminals
- Open backup power wire to the ECM
- Failing ECM memory circuit
How to fix P1600
- Check the ECM BATT fuse — separate from main ECM power
- Inspect battery cables and grounds
- Verify backup voltage at the ECM pin
- Confirm adaptations relearn after a drive cycle
- Repair the backup feed rather than replacing the ECM first