Diagnostics and testing of the charging system (Discovery 3)

General form

For Battery Status Indicator see section 414-01 "Battery and wiring" manuals for service stations. When checking and charging the battery, follow the instructions for the equipment used at the service station.

The generator is an intelligent system that is able to take into account changes in temperature and optimize battery charging.

Refer to section 414-02 for a detailed description of system design and operation «Generator and regulator» in the workshop manual.

Inspection and verification

1. Check the customer's complaint.

2. Visually inspect for obvious mechanical and electrical problems.

Mechanical elements	Electrical systems
Generator Drive belt Drive belt tensioner Alternator Pulley Check the reliability of the generator mounting	Generator Battery Starter Wiring harnesses and electrical connectors Fuses Battery Electrical Junction Box (BJB) - fuse 20E Starter main fuse Charging indicator function CAN electrical circuits (Control Area Network) The engine control unit (ECM)

3. If an obvious cause of a problem you identified or described by the customer is found, correct the problem before proceeding to further action (if possible).

4. Use an approved diagnostic system or scan tool (tester), to retrieve all DTCs before referring to the symptom table or DTC index (DTC).

Clear all DTCs after troubleshooting.

Symptom table

Symptom	Possible reason	Actions taken
Charging indicator lamp does not light up	Lamp/circuit failure Generator malfunction CAN Electrical Circuit Malfunction ECM malfunction	Check up work of a control lamp at the included ignition and the switched-off engine. Replace bulbs or repair circuits as needed. Check for DTCs (DTC), indicating a fault in the alternator, CAN, or ECM.
Charging indicator lamp is constantly on / the battery is discharging	Broken accessory drive belt Alternator pulley slip on shaft Malfunction generator Battery wire failure CAN Electrical Circuit Malfunction ECM malfunction	Check battery and alternator wires. Refer to electrical manuals. Check for DTCs (DTC), indicating a malfunction of the generator. Check the condition of the accessory drive belt and its tension (see visual inspection table). Make sure the pulley does not spin independently of the alternator. Check for DTCs (DTC), indicating a CAN or ECM malfunction.
Periodic activation of the charging indicator lamp	Accessory Drive Belt Slip Battery wire failure Generator wiring fault Generator malfunction CAN Electrical Circuit Malfunction	Check the condition of the accessory drive belt and its tension (see visual inspection table). Check battery and alternator wires. Refer to electrical manuals. Check for DTCs (DTC), indicating a malfunction of the generator or CAN bus. Please note that the use of a portable power supply or a starter/charger may cause the pilot lamp to illuminate until the devices are turned off.
The battery is discharging without the charge indicator light on	Battery failure Static battery discharge Break in the generator circuit	Check the condition of the battery, check the battery for static discharge. Check for DTCs (DTC), indicating a malfunction of the generator. The alternator control circuit may short to ground without setting DTCs. If no other causes of discharge are found, check this circuit. Refer to electrical manuals.
Noise (mechanical)	Accessory Drive Belt Slip Generator malfunction	Check the condition of the accessory drive belt and its tension (see visual inspection table). Disconnect the accessory drive belt and check that the alternator rotates freely.

Fault code table

NOTE: Universal Scan Tools may not read the listed codes, or may only read 5-digit codes. Match the 5 digits from the scan tool with the first 5 digits of the listed 7 digit code to identify the problem (the last 2 digits give additional information read by the diagnostic system approved by the manufacturer).

NOTE: See Section 303-14 for a complete list of ECM DTCs "Electronic engine management system" in the workshop manual.

Diagnostic trouble code	Description	Possible reasons	Actions taken
P062200	Generator field terminal circuit	Alternator circuit malfunction Generator malfunction	Refer to the electrical manual and check the generator electrical circuit. Repair/replace as needed. See the relevant section of the workshop manual.
P062500	Low voltage in the generator excitation terminal circuit	Voltage sensing circuit: high resistance Generator B+ circuit intermittent high resistance Generator control circuit - short to ground	Check the charging circuit fuse. Check charging voltage. Check the electrical circuits of the charging system. Refer to electrical manuals. If no faults are found in the electrical circuits, install a new alternator. See the relevant section of the workshop manual. Clear DTCs and check for correct operation.
P062600	High voltage in the generator excitation terminal circuit	Alternator Connector: Loose/Not Connected Generator control circuit short to voltage Generator control circuit high resistance	Check charging voltage. Check the electrical circuits of the charging system. Refer to electrical manuals. If no faults are found in the electrical circuits, install a new alternator. See the relevant section of the workshop manual. Clear DTCs and check for correct operation.
P065B00	Generator Control Electrical Range/Performance Problems	Generator control circuit - short to ground Generator control circuit short to battery High resistance in the generator control circuit	Check generator and electrical circuits. Refer to electrical manuals. Repair/replace as needed. Clear DTCs and check for correct operation.