Honda Civic. Manual — part 14

7. Compare the voltage noted in step 5 to the voltage in step 6.

Is the difference between the two voltage readings less then 3 V?

YES - Intermittent failure, the system is OK at this time. Check for loose
terminals at the ABS modulator-control unit 25P connector. Refer to
INTERMITTENT FAILURES TROUBLESHOOTING . If the code resets
after clearing, replace the ABS modulator-control unit: Except Si model (see
REMOVAL - EXCEPT SI MODEL ), Si model (see REMOVAL - SI
MODEL ).

NO - Check for loose terminals in the ABS modulator-control unit 25P
connector. If necessary, substitute a known-good ABS modulator-control unit:
Except Si model (see REMOVAL - EXCEPT SI MODEL ), Si model (see
REMOVAL - SI MODEL ), and retest.

8. Turn the ignition switch to LOCK (0).
9. Disconnect the ABS modulator-control unit 25P connector.

10. Measure voltage between ABS modulator-control unit 25P connector terminal

No. 8 and body ground.

Fig. 25: Measuring Voltage Between ABS Modulator-Control Unit 25P
Connector Terminal No. 8 And Body Ground

Is there battery voltage?

YES - Go to step 11.

NO - Repair open in the wire between the No. 3 FSR (30 A) fuse in the under-

2008 Honda Civic GX

2006-08 BRAKES ABS System - Civic (All Except Hybrid)

hood fuse/relay box and the ABS modulator-control unit.

11. Turn the ignition switch ON (II).
12. Measure voltage between ABS modulator-control unit 25P connector terminal

No. 16 and body ground.

Fig. 26: Measuring Voltage Between ABS Modulator-Control Unit 25P
Connector Terminal No. 16 And Body Ground

Is there battery voltage?

YES - Check for loose terminals in the ABS modulator-control unit 25P
connector. If necessary, substitute a known-good ABS modulator-control unit:
Except Si model (see REMOVAL - EXCEPT SI MODEL ), Si model (see
REMOVAL - SI MODEL ), and retest.

NO - Repair open in the wire between the No. 4 (7.5 A) fuse in the under-dash
fuse/relay box and the ABS modulator-control unit.

DTC 62-21: MODULATOR-CONTROL UNIT IG HIGH VOLTAGE

1. Turn the ignition switch ON (II).
2. Clear the DTC with the HDS.
3. Turn the ignition switch to LOCK (0), then start the engine.
4. Check for DTCs with the HDS.

Is DTC 62-21 indicated?

YES - Go to step 5.

2008 Honda Civic GX

2006-08 BRAKES ABS System - Civic (All Except Hybrid)

NO - Intermittent failure, the system is OK at this time.

5. Using a voltmeter, measure the voltage between the battery terminals.

Compare the voltage measured at the battery with the voltage shown in the
ABS DATA LIST with the HDS.

Is there a voltage difference of 3 V or more?

YES - Replace the ABS modulator-control unit: Except Si model (see
REMOVAL - EXCEPT SI MODEL ), Si model (see REMOVAL - SI
MODEL ), and retest.

NO - Check the battery (see BATTERY TEST ), and troubleshoot the
alternator regulator circuit: Except Si model (see ALTERNATOR AND
REGULATOR CIRCUIT TROUBLESHOOTING ), Si model (see
ALTERNATOR AND REGULATOR CIRCUIT
TROUBLESHOOTING ). Also check for loose terminals in the ABS
modulator-control unit 25P connector. If it is OK, replace the ABS modulator-
control unit: Except Si model (see REMOVAL - EXCEPT SI MODEL ), Si
model (see REMOVAL - SI MODEL ).

DTC 71-21: RIGHT-FRONT OR LEFT-REAR DIFFERENT DIAMETER TIRE MALFUNCTION;
DTC 71-22: LEFT-FRONT OR RIGHT-REAR DIFFERENT DIAMETER TIRE MALFUNCTION;
DTC 71-23: RIGHT-FRONT AND RIGHT-REAR DIFFERENT DIAMETER TIRE MALFUNCTION;
DTC 71-24: LEFT-FRONT AND LEFT-REAR DIFFERENT DIAMETER TIRE MALFUNCTION;
DTC 71-25: RIGHT-FRONT AND LEFT-FRONT DIFFERENT DIAMETER TIRE MALFUNCTION;
DTC 71-26: RIGHT-REAR AND LEFT-REAR DIFFERENT DIAMETER TIRE MALFUNCTION

DIFFERENT DIAMETER TIRE MALFUNCTION

NOTE:

The DTC will be indicated when the vehicle has a different
diameter tire(s) compared to the other tire(s).

DTC

Sectional

Note

71-21

Right-front or left-rear

71-22

Left-front or right-rear

71-23

Right-front and right-rear

71-24

Left-front and left-rear

2008 Honda Civic GX

2006-08 BRAKES ABS System - Civic (All Except Hybrid)

1. Check the tires for proper inflation (see WHEEL ALIGNMENT ).
2. Turn the ignition switch ON (II).
3. Clear the DTC with the HDS.
4. Turn the ignition switch to LOCK (0).
5. Test-drive the vehicle.
6. Check for DTCs with the HDS.

Is DTC 71-21, 71-22, 71-23, 71-24, 71-25, or 71-26 indicated?

YES - Replace all four tires with the proper size (see WHEEL
ALIGNMENT ).

NO - Intermittent failure, the system is OK at this time.

DTC 81-XX*: CENTRAL PROCESSING UNIT (CPU) INTERNAL CIRCUIT MALFUNCTION

* : Subcode (Except DTC 81-11, 81-51, and 81-52)

1. Turn the ignition switch ON (II).
2. Clear the DTC with the HDS.
3. Turn the ignition switch to LOCK (0), then turn it ON (II) again.
4. Check for DTCs with the HDS.

Is DTC 81-xx indicated?

YES - If the DTC 81-11, 81-51, or 81-52 is indicated at the same time, do the
DTC 81-11,81-51, or 81-52 troubleshooting (see DTC 81-xx*: Central
Processing Unit (CPU) Internal Circuit Malfunction ). If DTC 81-11, 81-
51, or 81-52 is not indicated, replace the ABS modulator-control unit: Except
Si model (see REMOVAL - EXCEPT SI MODEL ), Si model (see
REMOVAL - SI MODEL ), and retest.

NO - Intermittent failure, the system is OK at this time.

71-25

Right-front and left-front

71-26

Right-rear and left-rear

2008 Honda Civic GX

2006-08 BRAKES ABS System - Civic (All Except Hybrid)