General Information

Engine Control

P1502 Battery Not Charging Diagnostic - General Information

Component Location





General Description

Many control units have applied to vehicle as it becomes more electronically. These units control their own system based on information from diverse sensors. Therefore necessity of common use of diverse sensor information and importance of stable power supply are gathering strength. Battery sensor is mounted on battery (-) terminal. It transmits battery voltage, current, temperature information to ECM. ECM controls generating voltage by duty cycle based on these signals.

DTC Description

ECM sets this code when the battery charging current from battery sensor is too low.

DTC Detecting Condition





Diagnostic Circuit Diagram





Signal Waveform & Data
















Fig 1) Normal waveforms of IG, L terminal of alternator during charge warning lamp is ON
Fig 2) Normal waveforms of IG, L terminal of alternator during charge warning lamp is OFF
Fig 3) Normal waveforms of COM, FR terminal of alternator at idle
Fig 4) Normal waveforms of COM, FR terminal of alternator under connector disconnected condition