2006 SUZUKI SX4 AIR

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Step 2. DTC check, record and clearance
First, referring to “DTC Check”, check DTC and pending
DTC. If DTC exists, print or write down DTC and then
clear malfunction DTC(s) by referring to “DTC
Clearance”. Malfunction DTC indicates malfunction in
the system but it is not possible to know from it whether
the malfunction is occurring now or it occurred in the
past and normal condition has been restored. In order to
know that, check symptom in question according to Step
5 and then recheck DTC according to Step 6.
Diagnosing a trouble based on the DTC in this step only
or failure to clear the DTC in this step may result in an
faulty diagnosis, trouble diagnosis of a normal circuit or
difficulty in troubleshooting which is otherwise
unnecessary.
Step 3 and 4. Visual inspection
As a preliminary step, be sure to perform visual check of
the items that support proper function of the 4WD control
system referring to “Visual Inspection”.
Step 5. Trouble symptom confirmation
Check trouble symptoms based on information obtained
in “Step 1. Customer complaint analysis: ” and “Step 2.
DTC check, record and clearance: ”.
Also, reconfirm DTC according to “DTC Confirmation
Procedure” described in each DTC flow.
Step 6 and 7. Rechecking and record of DTC
Refer to “DTC Check” for checking procedure.
Step 8. 4WD control symptom diagnosis
Check the parts of the system suspected as a possible
cause referring to “4WD Control Symptom Diagnosis”.
Step 9. Troubleshooting for DTC
Based on the DTC indicated in Step 6 / 7 and referring to
“applicable DTC flow”, locate the cause of the trouble,
namely in a sensor, switch, wire harness, connector,
coupling assembly, 4WD control module or other part
and repair or replace faulty parts.
Step 10. Check for intermittent problem
Check parts where an intermittent trouble is easy to
occur (e.g. wire harness, connector, etc.), referring to
“Intermittent and Poor Connection Inspection in Section
00” and related circuit of DTC recorded in Step 2.
Step 11. Final confirmation test
Confirm that the problem symptom has gone and the
vehicle is free from any abnormal conditions. If what has
been repaired is related to the malfunction DTC, clear
the DTC once and check to ensure that no malfunction
DTC is indicated.4WD Position Indicator Operation CheckS6RW0D3204002
1) Turn ignition switch to OFF position.
2) Check that 4WD position indicators turn on for about
2 seconds and then turns off.
If any faulty condition is found, proceed to “4WD
Position Indicator Does Not Come ON at Ignition
Switch ON but Engine Stops” or “4WD Position
Indicator Remains ON Steady at Ignition Switch ON”.
4WD Control System Operation InspectionS6RW0D3204003
NOTE
• It automatically changes into “4WD-auto”
position, when the vehicle speed becomes
specified speed or more at “4WD-lock”
position. It is “4WD-auto” position until
switch will be selected to “4WD-lock”
position at next time.
• When ABS operates while changed of each
position, it is discontinued of change. End
of the ABS operation, and then returned to
the position of before.

1) Inspect switch operation from “4WD-auto” to “2WD”
as follows.
a) Start engine.
b) Push 2WD/4WD switch to “2WD” position.
c) Check that 4WD AUTO indicator and 4WD
LOCK indicator not come ON.
2) Inspect switch operation from “2WD” to “4WD-auto”
as follows.
a) Start engine.
b) Push 2WD/4WD switch to “AUTO” position.
c) Check that 4WD AUTO indicator comes ON
steady and 4WD LOCK indicator not come ON.
3) Inspect switch operation from “4WD-auto” to “4WD-
lock” as follows.
a) Start engine.
b) Push 2WD/4WD switch to “LOCK” position, and
keep it for 3 seconds or more.
c) Check that 4WD AUTO indicator not come ON
and 4WD LOCK indicator comes ON steady.
4) Inspect switch operation from “4WD-lock” to “4WD-
auto” as follows.
a) Start engine.
b) Push 2WD/4WD switch to “AUTO” position.
c) Check that 4WD AUTO indicator comes ON
steady and 4WD LOCK indicator not come ON.

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DTC TableS6RW0D3204007
NOTE
“O” in transfer position indicator column of the above table means indicator lights up when DTC is
detected.

Fail-Safe TableS6RW0D3204008
This function is provided by the safe mechanism that assures safe driveability even when the coupling assembly,
switch, sensor or its circuit fails. The following table shows the fail safe function for each fail condition of sensor,
coupling assembly, switch, 4WD control module or its circuit. DTC No. Detecting itemDetecting condition
(DTC will set when detecting)4WD
position
Indicator
) C12404WD control module power
supply circuit malfunctionBattery voltage is lower than lower limit voltage for
4WD control module diagnosis.{
) C1243Internal circuit malfunction of
4WD control moduleInternal power supply malfunction of 4WD control
module{
) C1250Coupling air temperature sensor
openSensor output voltage too high{
) C1251Coupling air temperature sensor
shortSensor output voltage too low{
) C1252 Coupling assembly open2WD/4WD switch is changed of 4WD lock position,
and then vehicle is not changed for more than 5
seconds.{
) C1253 Coupling assembly short2WD/4WD switch is changed of 4WD lock position,
and then vehicle is not changed for more than 5
seconds.{
) C1254 2WD/4WD switch malfunctionDifferent switch combination from specification is
detected more than 5 seconds.{
) U0073Control module communication
bus offTransmitting and receiving error of 4WD control
module for specified time continuously{
) U0100 Lost communication with ECMReceiving error of 4WD control module from ECM
for specified time continuously{
) U0121Lost communication with ABS /
ESP® control moduleReceiving error of 4WD control module from ABS /
ESP® control module for specified time
continuously{
) U0155Lost communication with
instrument panel cluster control
moduleReceiving error of 4WD control module from
combination meter for specified time continuously{
DTC No. Trouble Area Fail-Safe Operation
)C12404WD control module power supply circuit
malfunction4WD control module controls the current and
fixed the vehicle to 2WD position.
)C1243Internal circuit malfunction of 4WD control
module
)C1250 Coupling air temperature sensor open
)C1251 Coupling air temperature sensor short
)C1252 Coupling assembly open
)C1253 Coupling assembly short
)C1254 2WD/4WD switch malfunction
)U0073 Control module communication bus off
)U0100 Lost communication with ECM
)U0121Lost communication with ABS / ESP® control
module
)U0155Lost communication with instrument panel
cluster control module

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Scan Tool DataS6RW0D3204009
Scan Tool Data Definitions
Accel pedal Pos (Accelerator pedal position) (%)
Accelerator pedal opening ratio detected by signal on
CAN communication line fed from ECM.
Engine Speed (RPM)
This parameter indicates engine revolution calculated by
4WD control module.
4WD mode (2WD / AUTO / LOCK / ABS mode / Yaw
cont / ESP® req)
This parameter indicates 4WD mode according to 2WD/
4WD switch signal status detected by 4WD control
module.
4WD current (A)
This parameter indicates input current of coupling
assembly.
Battery voltage (V)
This parameter indicates battery voltage detected by
4WD control module.Coupling temp (°C, °F)
Coupling temperature detected by coupling air
temperature sensor installed in coupling assembly.
Wheel speed (F), Wheel speed (R) (km/h, mph)
Wheel speed is an ABS / ESP® control module internal
parameter. It is computed by reference pulses from the
wheel speed sensor.
F-R Wheel speed diff (Front-rear wheel speed
differential) (rpm)
This parameter indicates rotation difference between
front wheel and rear wheel detected by 4WD control
module.
4WD duty (%)
This parameter indicates operation rate of coupling
assembly. Scan tool data Vehicle conditionNormal condition / reference
values
) Accel pedal PosIgnition switch ON after
warmed up engineAccelerator pedal released 0 – 5%
Accelerator pedal depressed
fully90 – 100%
) Engine speed At engine idle speed Engine idle speed is display
) 4WD mode2WD/4WD switch selected to 2WD position 2WD
2WD/4WD switch selected to AUTO position AUTO
2WD/4WD switch selected to LOCK position LOCK
ABS operating ABS mode
Ignition switch ON and engine stop Relay off
Stability control operating Yaw cont
ESP® operating ESP® mode
) 4WD current Engine running 0 – 200 mA
) Battery voltage At engine idle speed 10 – 14 V
) Coupling temp Engine running –40 °C – 100 °C (–40 °F – 212 °F)
) Wheel speed (F) Vehicle stop 0 km/h, 0 MPH
) Wheel speed (R) Vehicle stop 0 km/h, 0 MPH
) F-R Wheel speed
DiffVehicle stop 0 rpm
) 4WD dutyIgnition switch ON and 2WD/4WD switch selected to
2WD position0%

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Rear Differential Symptom DiagnosisS6RW0D3204011
4WD Control Symptom DiagnosisS6RW0D3204012
Diagnose 4WD system after performing the following inspections.
• Perform 4WD control system check referring to “4WD Control System Check”. Condition Possible cause Correction / Reference Item
Gear noiseDeteriorated or water mixed lubricantRepair and replenish referring to “Rear
Differential Oil Change”.
Inadequate or insufficient lubricantRepair and replenish referring to “Rear
Differential Oil Change”.
Maladjusted backlash between drive
bevel pinion and gearAdjust as prescribed referring to “Rear
Differential Disassembly and Reassembly”.
Improper tooth contact in the mesh
between drive bevel pinion and gearAdjust or replace referring to “Rear Differential
Disassembly and Reassembly”.
Loose drive bevel gear securing boltsReplace or retighten referring to “Rear
Differential Disassembly and Reassembly”.
Damaged differential gear(s) or
differential pinion(s)Replace referring to “Rear Differential
Inspection”.
Bearing noise(Constant noise) Deteriorated or water
mixed lubricantRepair and replenish referring to “Rear
Differential Oil Change”.
(Constant noise) Inadequate or
insufficient lubricantRepair and replenish referring to “Rear
Differential Oil Change”.
(Noise while coasting) Damaged
bearing(s) of drive bevel pinionReplace referring to “Rear Differential
Inspection”.
(Noise while turning) Damaged
differential side bearing(s) or axle
bearing(s)Replace referring to “Rear Differential
Inspection”.
Oil leakageClogged breather plugClean.
Worn or damaged oil sealReplace.
Excessive oilAdjust oil level referring to “Rear Differential Oil
Change”.
Loose differential carrier boltsReplace or retighten.
Condition Possible cause Correction / Reference Item
4WD system does not
operate2WD/4WD switch faultyCheck switch referring to “2WD/4WD Switch
Inspection”.
Coupling air temperature sensor faultyCheck coupling air temperature sensor
referring to “Coupling Air Temperature Sensor
Inspection”.
Coupling assembly faultyCheck coupling assembly referring to
“Coupling Assembly Inspection”.
Wiring or grounding faultyRepair as necessary.
4WD control module faultyCheck 4WD control module referring to
“Inspection of 4WD Control Module and Its
Circuits”.
MAF sensor faultyCheck MAF sensor and its circuit.
Accelerator pedal position (APP) sensor
faultyCheck accelerator pedal position (APP) sensor
and its circuit.
CKP sensor faultyCheck CKP sensor and its circuit.
Front and/or rear wheel speed sensor
faultyCheck front and/or rear wheel speed sensor
and its circuit.
Steering angle sensor faultyCheck steering angle sensor and its circuit.
ABS / ESP® control module faultyCheck ABS / ESP
® control module and its
circuit.
ECM faultyCheck ECM and its circuit.
NoiseDamaged or worn bearing(s)Refer to “Rear Differential Inspection”.

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4WD Position Indicator Remains ON Steady at Ignition Switch ONS6RW0D3204014
Wiring Diagram
Refer to “4WD Position Indicator Does Not Come ON at Ignition Switch ON but Engine Stops”.
Circuit Description
Transfer position indicator operates according to the signal from 4WD control module. If the 4WD control system is in
good condition, 4WD position indicator light up for 2 seconds when ignition switch is turned to ON position, and then
turned to OFF position. If an abnormality is detected in the system, 4WD position indicator remains lighting.
Troubleshooting3CAN communication circuit check
1) Check CAN communication circuit between combination
meter and 4WD control module referring to “DTC U0073:
Control Module Communication Bus Off”.
Is CAN communication circuit in good condition?Go to Step 4. Repair or replace.
4“METER” fuse check
1) Turn ignition switch to OFF position.
2) Check for fuse blown to “METER” fuse in junction block
assembly.
Is “METER” fuse in good condition?Go to Step 5. Replace “METER” fuse
and check for short.
5Combination meter power supply check
1) Remove combination meter referring to “Combination
Meter Removal and Installation in Section 9C”.
2) Check proper connection to “WHT/RED” and “BLK” wire
terminal of combination meter connector.
3) If OK, then turn ignition switch to ON position and
measure voltage between “WHT/RED” wire terminal of
combination meter connector and vehicle body ground.
Is it 10 – 14 V?Go to Step 6. “WHT/RED” wire is
open circuit.
6Combination meter ground circuit check
1) Turn ignition switch to OFF position.
2) Measure resistance between “BLK” wire terminal of
combination meter connector and vehicle body ground.
Is resistance 1
Ω or less?Substitute a known-
good combination meter
and recheck. If 4WD
position indicator still
remains OFF, substitute
a known-good 4WD
control module and
recheck.“BLK” wire is open or
high resistance circuit. Step Action Yes No
Step Action Yes No
1Check DTC
1) Check DTC referring to “DTC Check”.
Is there any DTC(s)?Perform DTC flow to
repair and retry.Go to Step 2.
2CAN communication circuit check
1) Check CAN communication circuit between combination
meter and 4WD control module referring to “DTC U0073:
Control Module Communication Bus Off”.
Is CAN communication circuit in good condition?Substitute a known-
good combination meter
and recheck. If 4WD
position indicator still
remains off, substitute a
known-good 4WD
control module and
recheck.Repair or replace.

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DTC C1243: Internal Circuit Malfunction of 4WD Control ModuleS6RW0D3204016
DTC Detecting Condition and Trouble Area
DTC Confirmation Procedure
1) Clear DTC using scan tool.
2) Start engine and run it for 10 seconds. or more.
3) Stop vehicle and check DTC.
Troubleshooting
Substitute a known-good 4WD control module and recheck.3Ground circuit check
1) Turn ignition switch to OFF position.
2) Check for proper connection to “G26-10” terminal of
4WD control module connector.
3) If OK, measure resistance between “G26-10” terminal of
4WD control module connector and vehicle body
ground.
If resistance 1
Ω or less?Substitute a known-
good 4WD control
module and recheck.Repair ground circuit. Step Action Yes No
DTC detecting condition Trouble area
Internal power supply malfunction of 4WD control module 4WD control module

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DTC C1250: Coupling Air Temperature Sensor Circuit OpenS6RW0D3204017
Wiring Diagram
DTC Detecting Condition and Trouble Area
DTC Confirmation Procedure
1) Clear DTC using scan tool.
2) Turn ignition switch to ON position for 10 seconds.
3) Check DTC.
[A]: 4WD control module connector “G26” (viewed from harness side) 2. 4WD control module
1. Coupling air temperature sensor
DTC detecting condition Trouble area
Input signal from coupling air temperature sensor is higher than
specified value.• Coupling air temperature sensor
• Coupling air temperature sensor circuit
• 4WD control module
2
G26-25
G26-24ORN
BRN
5V
1
1 2 3
4 5
6 7 8 9 10 11
12
13
14 15 16
17 18 19
20
21 22
23
24 25 26
[A]
I7RW01320006-01

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Troubleshooting
Step Action Yes No
1Was “4WD control system check” performed?Go to Step 2. Go to “4WD Control
System Check”.
2Coupling air temperature sensor circuit check
1) Disconnect connector from coupling air temperature
sensor with ignition switch turned OFF.
2) Check for proper connection to “BRN” and “ORN”
terminals of coupling air temperature sensor connector.
3) If connection is OK, measure voltage between “BRN”
terminal of coupling air temperature sensor connector
and vehicle body ground with ignition switch turned ON.
Is it 4 – 6 V?Go to Step 3. Go to Step 5.
3Coupling assembly ground circuit check
1) Disconnect connector from 4WD control module with
ignition switch turned OFF.
2) Measure resistance between “ORN” terminal of coupling
air temperature sensor connector and “G26-24” terminal
of 4WD control module connector with ignition switch
turned OFF.
Is resistance below 5
Ω?Go to Step 4. “ORN” wire is open or
high resistance.
4Coupling air temperature sensor check
1) Check coupling air temperature sensor referring to
“Coupling Air Temperature Sensor Inspection”.
Is it in good condition?Substitute a known-
good 4WD control
module and recheck.Replace coupling air
temperature sensor.
5Coupling assembly circuit check
1) Disconnect connector from 4WD control module with
ignition switch turned OFF.
2) Check for proper connection to “G26-25” and “G26-24”
terminals of 4WD control module connector.
3) If connection is OK, measure resistance between “G26-
25” terminal of 4WD control module connector and
vehicle body ground.
Is resistance below 5
Ω?“BRN” wire is open or
high resistance circuit.Substitute a known-
good 4WD control
module and recheck.