Honda Civic. Manual — part 366

symptom/indication goes away with a known-good ECM/PCM, replace the
original ECM/PCM (see ECM/PCM REPLACEMENT ).

14. Do the gauge control module self-diagnostic function procedure (see SELF-

DIAGNOSTIC FUNCTION ).

Does the charging system indicator flash?

YES -Go to step 15.

NO -Replace the gauge control module (tach) (see REPLACEMENT ).

15. Turn the ignition switch OFF.
16. Disconnect the alternator 4P connector.
17. Connect alternator 4P connector terminal No. 3 and body ground with a jumper

wire.

Fig. 4: Connecting Alternator 4P Connector Terminal No. 3 And Body
Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

18. Turn the ignition switch ON (II).

Does the charging system indicator come on?

YES -Replace the alternator (see ALTERNATOR REMOVAL AND
INSTALLATION ), or repair the alternator (see ALTERNATOR
OVERHAUL ).

2008 Honda Civic GX

2006-08 ELECTRICAL Charging System (R18A1) - Civic (All Except Hybrid)

NO -Go to step 19.

19. Turn the ignition switch to LOCK (0).
20. Connect the HDS to the DLC (see step 2 on HOW TO USE THE HDS

(HONDA DIAGNOSTIC SYSTEM) ).

21. Turn the ignition switch ON (II).
22. Make sure the HDS communicates with the vehicle and the ECM/PCM. If it

doesn't, troubleshoot the DLC circuit (see DLC CIRCUIT
TROUBLESHOOTING ).

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

24. Disconnect ECM/PCM connector B (44P).
25. Check for continuity between ECM/PCM connector terminal B42 and body

ground.

Fig. 5: Checking For Continuity Between ECM/PCM Connector Terminal
B42 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Update the ECM/PCM if it does not have the latest software (see
UPDATING ECM/PCM ), or substitute a known-good ECM/PCM (see
SUBSTITUTING THE ECM/PCM ), then recheck. If the

NOTE:

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

2008 Honda Civic GX

2006-08 ELECTRICAL Charging System (R18A1) - Civic (All Except Hybrid)

symptom/indication goes away with a known-good ECM/PCM, replace the
original ECM/PCM (see ECM/PCM REPLACEMENT ).

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

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: Identifying VAT-40 (Or Equivalent Tester)
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?

2008 Honda Civic GX

2006-08 ELECTRICAL Charging System (R18A1) - Civic (All Except Hybrid)

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

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

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 (R18A1) - Civic (All Except Hybrid)