Diesel Data: Automotive Repair

Charging System Diagnosis

CHARGING SYSTEM DIAGNOSIS

TROUBLESHOOTING HINTS

Generator malfunction light does not go on when the ignition switch is turned to ON, before the engine starts.
- Check the generator malfunction light.

Generator malfunction light does not switch off after the engine starts.
- Check the IC voltage regulator inside the generator.

Discharged or overcharged battery.
- Check the IC voltage regulator inside the generator.

TROUBLESHOOTING GUIDE

The charging system troubleshooting guide is shown in the following steps.

STEP 1.

Q: Is the battery in good condition? (Refer to Chassis Electrical - Battery - On-vehicle Service - Battery Test). Battery Test

YES : Go to Step 2.

NO : Charge or replace the battery.

STEP 2.

Q: Is the generator drive belt in good condition? (Refer to General - Maintenance Service - Drive Belts (For Generator, Power Steering Pump and Air Conditioning) (Check)).

YES : Go to Step 3.

NO : Adjust the belt tension or replace the belt.

STEP 3.

Q: Does the generator malfunction light come on when the ignition switch is turned on?

YES : Go to Step 4.

NO : Check the ignition switch. (Refer to Chassis Electrical - Ignition Switch - Ignition Switch - Inspection). Ignition Switch Continuity Check
Check the generator malfunction light and its related circuits.
Check the generator. (Refer to Charging System - Generator Assembly - Inspection).

STEP 4.

Q: Does the generator malfunction light go out after starting the engine?

YES : Go to Step 5.

NO : Check the generator (Refer to Charging System - Generator Assembly - Inspection).

STEP 5.

Q: Is an oscilloscope available?

YES : Go to Step 6.

NO : Go to Step 7.

STEP 6.

Q: Does the oscilloscope show a normal wave pattern? (Refer to Charging System - On-vehicle Service - Wave Pattern Check Using an Oscilloscope). Oscilloscope Patterns and Waveforms

YES : Go to Step 7.

NO : Check the generator. (Refer to Charging System - Generator Assembly - Inspection).

STEP 7.

- Engine: 2,500 r/min
- Headlight: ON (high beam)
- Voltage between generator terminal B and the positive battery terminal
OK: 0.5 V or less

- Voltage between the negative battery terminal and generator body
OK: 0.5 V or less

Q: Are the generator output line and ground line in good condition?

YES : Go to Step 8.

NO : Check the generator output line and ground line.

STEP 8.

Q: Is the output current normal? (Refer to Charging System - On-vehicle Service - Output Current Test). Output Current Test

YES : Go to Step 9.

NO : Check the generator (Refer to Charging System - Generator Assembly - Inspection).

STEP 9.

Q: Is the regulated voltage normal? (Refer to Charging System - On-vehicle Service - Regulated Voltage Test). Regulated Voltage Test

YES : Go to Step 10.

NO : Check the generator (Refer to Charging System - Generator Assembly - Inspection).

STEP 10.

Q: Is the voltage drop in the generator output line normal?

YES : Generator is normal. Check other systems.

NO : Check the output line.