P1600 – ECM Backup Circuit (Toyota)

Description

The ECM detected a malfunction in the backup power circuit, which maintains memory and operational readiness.

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Symptoms

Check engine light on
Intermittent no-start
Loss of learned values
Unstable idle
ECM resets unexpectedly

Causes

Weak battery
Corroded battery terminals
Faulty ECM backup circuit
Damaged wiring
Poor ground connection

Diagnosis

Check battery voltage
Inspect terminals
Test ECM power supply
Check ground points
Scan for related codes

Repair

Clean terminals
Repair wiring
Replace battery
Repair ground points
Replace ECM if necessary