Honda Civic. Manual — part 358

NO - Repair open in the wire between the alternator and the ECM.

ALTERNATOR AND REGULATOR CIRCUIT TROUBLESHOOTING

1. Make sure the battery connections are good and the battery is sufficiently

charged.

2. Connect a VAT-40 (or equivalent tester), and turn the selector switch to

position 1 (starting).

Fig. 6: Turning Selector Switch To Position 1 (Starting)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

3. Start the engine. Hold the engine speed at 3,000 rpm, with no load until the

radiator fan comes on, then let it idle.

4. Raise the engine speed to 2,000 rpm, and hold it there.

Is the voltage over 15.1 V?

YES - Replace the alternator (see ALTERNATOR REMOVAL AND
INSTALLATION ), or rear housing assembly (see ALTERNATOR

2008 Honda Civic GX

2006-08 ELECTRICAL Charging System (K20Z3) - Civic (All Except Si)

OVERHAUL ).

NO - Go to step 5.

5. Release the accelerator pedal, and let the engine idle.
6. Turn off all the accessories. Select the charging test on the tester.
7. Remove the inductive pickup, and zero the ammeter.
8. Place the inductive pickup over the B terminal wire of the alternator so the

arrow points away from the alternator.

9. Raise the engine speed to 2,000 rpm, and hold it there.

Is the voltage less than 13.5 V?

YES - Go to alternator control circuit troubleshooting (see ALTERNATOR
CONTROL CIRCUIT TROUBLESHOOTING ).

NO - Go to step 10.

10. Apply a load with the VAT-40 until the battery voltage drops within 12-13.5

V.

Is the amperage 87.5 A or more?

YES - The charging system is OK.

NO - Replace the alternator (see ALTERNATOR REMOVAL AND
INSTALLATION ), or repair the alternator (see ALTERNATOR
OVERHAUL ).

ALTERNATOR CONTROL CIRCUIT TROUBLESHOOTING

1. Connect the Honda Diagnostic System (HDS) to the data link connector (DLC)

(see step 2 in HOW TO USE THE HDS (HONDA DIAGNOSTIC

NOTE:

If the charging system indicator is still on, replace the
alternator (see ALTERNATOR REMOVAL AND
INSTALLATION ).

2008 Honda Civic GX

2006-08 ELECTRICAL Charging System (K20Z3) - Civic (All Except Si)

SYSTEM) ).

2. Turn the ignition switch ON (II).
3. Make sure the HDS communicates with the vehicle and the engine control

module (ECM). If it doesn't, troubleshoot the DLC circuit (see DLC
CIRCUIT TROUBLESHOOTING ).

4. Check for DTCs (see GENERAL TROUBLESHOOTING

INFORMATION ). If a DTC is present, diagnose and repair the cause before
continuing with this test.

5. Disconnect the alternator 4P connector from the alternator.
6. Start the engine, and turn on the headlights to high beam.
7. Measure the voltage between alternator 4P connector terminal No. 2 and the

positive terminal of the battery.

Fig. 7: Measuring Voltage Between Alternator 4P Connector Terminal No.
2 And Positive Terminal Of Battery
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there 1 V or less?

YES - Go to step 11.

NO - Go to step 8.

8. Jump the SCS line with the HDS, then turn the ignition switch OFF.

NOTE:

This step must be done to protect the ECM from
damage.

2008 Honda Civic GX

2006-08 ELECTRICAL Charging System (K20Z3) - Civic (All Except Si)

9. Disconnect ECM connector B (44P).

10. Check for continuity between ECM connector terminal B41 and body ground.

Fig. 8: Checking Continuity Between ECM Connector Terminal B41 And
Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Repair short in the wire between the alternator and the ECM.

NO - Update the ECM if it does not have the latest software (see UPDATING
THE ECM ), or substitute a known-good ECM (see SUBSTITUTING THE
ECM ), then recheck. If the symptom/indication goes away with a known-good
ECM, replace the original ECM (see ECM REPLACEMENT ).

11. Jump the SCS line with the HDS, then turn the ignition switch OFF.

12. Disconnect ECM connector B (44P).
13. Check for continuity between ECM connector terminal B41 and alternator 4P

connector terminal No. 2.

NOTE:

This step must be done to protect the ECM from
damage.

2008 Honda Civic GX

2006-08 ELECTRICAL Charging System (K20Z3) - Civic (All Except Si)