Honda Civic. Manual — part 739

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair any short to body ground in the wires between the heater control
panel and the recirculation control motor.

NO -Go to step 9.

9. Turn the ignition switch ON (II), and check the same terminals for voltage to

body ground.

Fig. 27: Checking Voltage Between Body Ground And Heater Control
Panel 24P Connector Terminals No 16 And 17
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there any voltage?

YES -Repair any short to power in the wires between the heater control panel
and the recirculation control motor. This short may also damage the heater
control panel. Repair the short to power before replacing the heater control
panel.

NO -Go to step 10.

10. Turn the ignition switch to LOCK (0).
11. Check for continuity between the following terminals of the heater control

panel 24P connector and the recirculation control motor IP connector.

2008 Honda Civic EX

2006-08 HVAC Heating - Civic (All Except Hybrid)

CONTINUITY CHECK INDEX

Fig. 28: Checking Continuity Between Heater Control Panel 24P And
Recirculation Control Motor IP Connector Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Check for loose wires or poor connections at the heater control panel
24P connector and at the recirculation control motor 7P connector. If the
connections are good, substitute a known-good heater control panel, and
recheck. If the symptom/indication goes away, replace the original heater
control panel.

NO -Repair any open in the wires between the heater control panel and the
recirculation control motor.

HEATER CONTROL POWER AND GROUND CIRCUIT TROUBLESHOOTING

1. Check the No. 36 (10 A) fuse in the under-dash fuse/relay box.

Is the fuse OK?

YES -Go to step 2.

24P

7P

16

7

17

5

2008 Honda Civic EX

2006-08 HVAC Heating - Civic (All Except Hybrid)

NO -Replace the fuse, and recheck. If the fuse blows again, check for a short in
the No. 36 (10 A) fuse circuit.

2. Disconnect the heater control panel 24P connector.
3. Turn the ignition switch ON (II).
4. Measure the voltage between the heater control panel 24P connector terminal

No. 23 and body ground.

Fig. 29: Measuring Voltage Between Heater Control Panel 24P Connector
Terminal No 23 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES -Go to step 5.

NO -Repair open in the wire between the No. 36 (10 A) fuse in the under-dash
fuse/relay box and the heater control panel.

5. Turn the ignition switch to LOCK (0).
6. Check for continuity between the heater control panel 24P connector terminal

No. 21 and body ground.

2008 Honda Civic EX

2006-08 HVAC Heating - Civic (All Except Hybrid)

Fig. 30: Checking Continuity Between Heater Control Panel 24P
Connector Terminal No 21 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Check for loose wires or poor connections at the heater control panel
24P connector. If the connections are good, substitute a known-good heater
control panel, and recheck.

NO -Check for an open in the wire between the heater control panel and body
ground. If the wire is OK, check for poor ground at G504 (see CONNECTOR
TO HARNESS INDEX ).

POWER TRANSISTOR TEST

1. Remove the passenger's dashboard undercover (see PASSENGER's

DASHBOARD UNDERCOVER REMOVAL/INSTALLATION ).

2. Disconnect the 4P connector from the power transistor.
3. Measure the resistance between the No. 3 and No. 4 terminals of the power

transistor. It should be about 1.5 kohms.

If the resistance is within the specifications, go to step 4.

If the resistance is not within the specifications, replace the power
transistor.

NOTE:

Also check the blower motor. Power transistor failure
can be caused by a defective blower motor.

2008 Honda Civic EX

2006-08 HVAC Heating - Civic (All Except Hybrid)