2008 SUZUKI SWIFT Inspection of ecm and its circuits

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DTC U1140: Lost Communication with BCM (Reception Error)S7RS0B4604045
Wiring Diagram
Refer to “Wiring Diagram” under “DTC U1073: Control Module Communication Bus Off”.
DTC Detecting Condition and Trouble Area3
Check each control module connectors
1) Check connection of connectors of all control modules
communicating by means of CAN.
2) Check DTC for ESP ®.
Is DTC U1126 detected? Go to Step 4. Check for intermittent
trouble referring to
“Intermittent and Poor
Connection Inspection
in Section 00”.
4 CAN communication circuit check
1) Turn ignition switch to OFF position.
2) Disconnect connectors of ESP ® control module, BCM
and steering angle sensor communicating by means of
CAN.
3) Check CAN communication circuit for open, short and high resistance.
• Between ESP ® control module and BCM
• Between steering angle sensor and BCM
Is each CAN communication circuit in good condition? Repair or replace the
CAN communication
line.
Go to Step 5.
5 CAN communication circuit check
1) Disconnect connectors of all control modules
communicating by means of CAN.
2) Check CAN communication circuit between control modules other than Step 4 for open, short and high
resistance.
Is each CAN communication circuit in good condition? Go to Step 6. Repair or replace the
CAN communication
line.
6 DTC check for ESP®
1) Connect connectors of disconnected control modules
communicating by means of CAN.
2) Disconnect each connector. •ECM
• Keyless start control module
• Combination meter
• Steering angle sensor
•BCM
3) Check DTC for ESP ®.
Is DTC U1126 detected? Check ESP
® control
module power and
ground circuit. If circuits
are OK, substitute a
known-good ESP ®
hydraulic unit / control
module assembly and
recheck. Check applicable
control module power
and ground circuit. If
circuit is OK, substitute
a known-good
applicable control
module and recheck.
Step Action Yes No
DTC Detecting Condition
Trouble Area
BCM message data is missing from CAN communication. • CAN communication circuit
•BCM
• ESP® control module

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DTC TroubleshootingStep Action Yes No 1 Was “Electronic Stability Pr ogram Check” performed? Go to Step 2. Go to “Electronic
Stability Program
System Check”.
2 DTC check for ESP®
1) Check DTC for ESP ®.
Is DTC U1140 and DTC U1073 detected together? Go to “DTC U1073:
Control Module
Communication Bus
Off”.Go to Step 3.
3 DTC check for BCM
1) Check DTC for BCM.
Is DTC U1073 detected? Go to “DTC U1073 (No.
1073): Control Module
Communication Bus Off
in Section 10B”.Go to Step 4.
4 Check each control module connectors
1) Check connection of connectors of all control modules
communicating by means of CAN.
2) Check DTC for ESP ®.
Is DTC U1140 detected? Go to Step 4. Check for intermittent
trouble referring to
“Intermittent and Poor
Connection Inspection
in Section 00”.
5 CAN communication circuit check
1) Turn ignition switch to OFF position.
2) Disconnect connectors of ESP ® control module and
BCM communicating by means of CAN.
3) Check CAN communication circuit between ESP®
control module and BCM for open, short and high
resistance.
Is each CAN communication circuit in good condition? Repair or replace the
CAN communication
line.
Go to Step 6.
6 CAN communication circuit check
1) Disconnect connectors of all control modules
communicating by means of CAN.
2) Check CAN communication circuit between control modules other than Step 5 for open, short and high
resistance.
Is each CAN communication circuit in good condition? Go to Step 7. Repair or replace the
CAN communication
line.
7 DTC check for ESP®
1) Connect connectors of disconnected control modules
communicating by means of CAN.
2) Disconnect each connector. •ECM
• Keyless start control module
• Combination meter
• Steering angle sensor
•BCM
3) Check DTC for ESP ®.
Is DTC U1140 detected? Check ESP
® control
module power and
ground circuit. If circuits
are OK, substitute a
known-good ESP ®
hydraulic unit / control
module assembly and
recheck. Check applicable
control module power
and ground circuit. If
circuit is OK, substitute
a known-good
applicable control
module and recheck.

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Serial Data Link Circuit CheckS7RS0B6304009
CAUTION!
Be sure to perform “EPS System Check” before starting “Troubleshooting”.

Wiring DiagramVehicle pulls to one side
during straight driving
Poor performance of torque sensor
Check torque sensor referring to “Torque
Sensor and Its Circuit Inspection”.
Steering gear case assembly faulty Replace.
Poor recovery after turns Poor performance of torque sensor Check torque sensor referring to “Torque
Sensor and Its Circuit Inspection”.
Steering column faulty Replace.
Abnormal noise P/S motor (built in steering gear case
assembly) malfunction Replace steering gear case assembly.
No idle up P/S control module faulty Check P/S control module referring to
“Inspection of P/S Control Module and Its
Circuits”.
Condition Possible cause Correction / Reference Item
MBLK
RED
E52-11 E51-1
E51-2PPL/WHT
[A ]
12
3
4 5 67
89
11
10
12 13
141516
17 18 19 2010 9 8 7654 3 21
16 15 14 13 12 11
26 25 24 2322 21 20 19 18 17
32 31 30 29 28 27
[C]
8
79
12V
[B ]
11
12
GRY
LT GRN
/BLK
E52-1
E52-5
E49-1
GRNGRNWHTBLK
WHY
G28-25G28-31
RED/BLK
10
3
4
4
5 6
4
4
1 2
4
E49-2BLK
I7RS0B630003-01
[A]: Connector “E52” (viewed from harness side) 3. Junction block assembly 8. P/S control module
[B]: Connector “E49” (viewed from harness side) 4. Fuse 9. T o ECM, BCM, Air bag SDM control module and ABS control
module assembly
[C]: Connector “G28” (viewed from harness side) 5. Comb ination meter 10. Individual circuit fuse box No.1
1. Main fuse box 6. “EPS” warning light 11. Serial data circuit
2. Ignition switch 7. Date link connector (DLC)

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DTC TroubleshootingStep Action Yes No 1 Was “EPS System Check” performed? Go to Step 2. Go to “EPS System
Check”.
2 DTC check
DTC Check for ECM referring to “DTC Check in Section 1A”.
Is there any DTC detected? Go to applicable DTC
diag. flow.
Go to Step 3.
3 DTC check
1) Check ABS control module for DTC referring to “DTC
Check in Section 4E”.
Is there any DTC detected? Go to applicable DTC
diag. flow.
Go to Step 4.
4 Vehicle speed signal circuit check
1) With ignition switch turned OFF, disconnect connectors
from ECM.
2) Check ECM connector for proper connection.
3) If OK, turn ON ignition switch, measure voltage between “E23-25” wire terminal of ECM connector and body
ground.
Is voltage 4 – 5 V? Go to Step 6.
Go to Step 5.
5 Vehicle speed signal circuit check
1) With ignition switch turned OFF, disconnect P/S control
module connector “E52”.
2) Check for proper terminal connection to P/S control module connector and ECM connector.
3) If connections are OK, chec k that “Vehicle speed signal
circuit” is as following.
• Insulation resistance of “Vehicle speed signal circuit” wire harness is infinity between its terminal and other
terminals at ECM and P/S control module connector.
• Wiring resistance of “Vehicle speed signal circuit” is less than 1 Ω.
• Insulation resistance of “Vehicle speed signal circuit” between its circuit and vehicle body ground is infinity.
• Circuit voltage between “Vehicle speed signal” circuit and ground circuit is 0 – 1 V with ignition switch turned
ON.
Is circuit in good condition? Replace P/S control
module.
Repair or replace
defective circuit.
6 ECM voltage check
1) Connect P/S control mo dule and ECM connectors.
2) Check ECM for vehicle speed signal output referring to “Inspection of ECM and Its Circuits in Section 1A”.
Is check result in good condition? Replace P/S control
module.
Replace ECM.

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DTC TroubleshootingStep Action Yes No 1 Was “EPS System Check” performed? Go to Step 2. Go to “EPS System
Check”.
2 DTC check
1) Clear DTC(s) referring to “DTC Clearance”.
2) Run engine at idle speed.
3) Check if any DTC is detecte d referring to “DTC Check”.
Is DTC C1122 still detected? Go to Step 3. Check intermittent
trouble referring to
“Intermittent and Poor
Connection Inspection
in Section 00”.
3 DTC check
1) Check ECM for DTC referring to “DTC Check in Section
1A”.
Is there any DTC related to engine speed? Go to applicable DTC
diag. flow.
Go to Step 4.
4 Engine speed signal circuit check
1) With ignition switch turned OFF, disconnect P/S control
module connector.
2) Check P/S control module connector for proper connection.
3) If OK, turn ON ignition switch, measure voltage between “E52-12” wire terminal of P/S control module connector
and vehicle body ground.
Is voltage 10 – 14 V? Go to Step 6.
Go to Step 5.
5 1) With ignition switch turned OFF, disconnect ECM connector.
2) Check for proper connection to the P/S control module and ECM at each “Engine speed signal circuit” terminal.
3) If connections are OK, chec k that “Engine speed signal
circuit” is as following.
• Insulation resistance of “Engine speed signal circuit” wire is infinity between its terminal and other terminals
at ECM and P/S control module connector.
• Wiring resistance of “Engine speed signal circuit” terminal are less than 1 Ω.
• Insulation resistance of “Engine speed signal circuit” between its terminal and vehicle body ground is
infinity.
• Circuit voltage between “Engine speed signal circuit” and ground circuit is 0 – 1 V with ignition switch turned
ON.
Is circuit in good condition? Go to Step 6.
Repair engine speed
signal circuit.
6 ECM voltage check
1) Connect P/S control mo dule and ECM connectors.
2) Check ECM for engine speed signal and vehicle speed signal output voltage to P/S control module referring to
“Inspection of ECM and Its Circuits in Section 1A”.
Is check result in good condition? Substitute a known-
good P/S control
module and recheck.
Substitute a known-
good ECM and recheck.

Downloaded from www.Manualslib.com manuals search engine 6C-36 Power Assisted Steering System:
Voltage Check1) Remove console box.
2) Check for voltage at each terminal with co nnectors connected to the P/S control module.
NOTE
As each terminal voltage is affected by the battery voltage, confirm if the battery voltage is 11 V or
more when ignition switch is ON.
*: The voltage of this circuit may not be checked by voltmeter. If so, use oscilloscope.

Terminal Wire colorCircuit Normal voltage Remarks
E49-1 GRN Main power supply for
internal memory and P/S
motor 10 – 14 V
—
E49-2 BLK Ground for P/S control
module Below 0.3 V
—
E51-1 BLK Motor output 1 *0 – 1 V
↑↓
10 – 14 V
(“Reference
waveform No.1: ”, “Reference
waveform No.2:
”and “Reference
waveform No.3: ”) • Engine idling and steering wheel at
straight position
• Voltage between “E51-1” and vehicle body ground
E51-2 RED Motor output 2 *0 – 1 V
↑↓
10 – 14 V
(“Reference
waveform No.1: ”, “Reference
waveform No.2: ” and “Reference
waveform No.3: ”) • Engine idling and steering wheel at
straight position
• Voltage between “E51-2” and vehicle body ground
E52-1 LT GRN/BLK Ignition switch signal for P/S
control module 10 – 14 V Ignition switch ON
E52-2 — —— —
E52-3 — —— —
E52-4 PPL Vehicle speed signal *0 – 1 V
↑↓
8 – 14 V
(“Reference
waveform No.9”
under “Inspection of
ECM and Its Circuits in Section 1A”.) • Ignition switch ON
•Front left tire tu
rned quickly with right
tire locked
E52-5 GRY “EPS” warning light 0 V “EPS” warning light OFF
E52-6 BLU Torque sensor signal (Sub) About 0 – 2.5 V
• Steering wheel with left turn
• Out put voltage varies linearly
depending on steering force
About 2.5 V Steering wheel at free
About 2.5 – 6 V • Steering wheel with right turn
• Out put voltage varies linearly
depending on steering force
E52-7 — —— —
E52-8 GRN Main power supply for torque
sensor About 12 V• Ignition switch ON
• Check voltage between “E52-8” and
“E52-9” terminals
E52-9 BRN Ground for torque sensors Below 0.3 V —
E52-10 — —— —

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E52-11 PPL/WHT Data link connector——
E52-12 BRN Engine speed signal *0 – 1 V
↑↓
8 – 14 V
(“Reference
waveform No.30” and “Reference
waveform No.31”
under “Inspection of
ECM and Its Circuits in Section 1A”.) Engine idling
E52-13 — —— —
E52-14 RED/BLU P/S operation signal (idle up
signal) About 12 V Ignition switch ON
0 – 1 V Engine idling and turned steering
wheel to the right or left until it stops
E52-15 — —— —
E52-16 YEL Torque sensor internal failure
signal About 5 V At the moment of Ignition switch ON
0 V Ignition switch ON
E52-17 — —— —
E52-18 WHT Torque sensor signal (Main) About 0 – 2.5 V
• Steering wheel with left turn
• Out put voltage varies linearly
depending on steering force
About 2.5 V Steering wheel at free
About 2.5 – 6 V • Steering wheel with right turn
• Out put voltage varies linearly
depending on steering force
E52-19 GRY Ground for shield wire Below 0.3 V—
E52-20 RED 5 V reference power supply
for torque sensor About 5 V• Ignition switch ON
• Check voltage between “E52-20”
and “E52-9” terminals
Terminal Wire color
Circuit Normal voltage Remarks

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Diagnostic Information and Procedures
A/C System Symptom DiagnosisS7RS0B7214001
ConditionPossible cause Correction / Reference Item
No cool air comes out (A/
C system does not
operate) No refrigerant
Perform recovery, evacuation and charge
referring to “Operation Procedure for
Refrigerant Charge”.
Fuse blown Check related fuses, and then check for short
circuit to ground.
A/C switch faulty Check A/C switch referring to “A/C Switch
Inspection”.
Blower speed selector faulty Check blower speed selector referring to
“Blower Speed Selector Inspection in Section
7A”.
Evaporator thermistor (Evaporator
temperature sensor) faulty Check evaporator thermistor (evaporator
temperature sensor) referring to “Evaporator
Thermistor (Evaporator Temperature Sensor)
Inspection”.
A/C refrigerant pressure sensor faulty Check A/C refrigerant pressure sensor
referring to “A/C Refrigerant Pressure Sensor
and Its Circuit Inspection”.
Wiring or grounding faulty Repair as necessary.
ECM faulty Check ECM referring to “A/C System
Inspection at ECM”.
Magnet clutch faulty Check magnet clutch referring to “Magnet
Clutch Inspection”.
Compressor drive belt loosened or
broken Adjust or replace drive belt.
Compressor faulty Check compressor.
Compressor relay faulty Check compressor relay referring to
“Compressor Relay Inspection”.
BCM faulty Check BCM referring to “Inspection of BCM
and its Circuits in Section 10B”.
No cool air comes out
(radiator cooling fan
motor does not operate) Fuse blown
Check related fuses, and then check for short
circuit to ground.
Wiring or grounding faulty Repair as necessary.
Radiator cooling fan motor relay faulty Check radiator cooling fan motor relay
referring to “Radiator Cooling Fan Relay
Inspection in Section 1F”.
Radiator cooling fan motor faulty Check radiator cooling fan motor referring to
“Radiator Cooling Fan Removal and
Installation in Section 1F”.
ECM and/or its circuit faulty Check ECM and/or its circuit referring to “A/C
System Inspection at ECM”.
No cool air comes out
(blower motor does not
operate) Fuse blown
Check related fuses, and then check for short
circuit to ground.
Blower motor relay faulty Check blower motor relay referring to “Blower
Motor Relay Inspection in Section 7A”.
Blower motor resistor faulty Check blower motor resistor referring to
“Blower Motor Resistor Inspection in Section
7A”.
Blower speed selector faulty Check blower speed selector referring to
“Blower Speed Selector Inspection in Section
7A”.
Wiring or grounding faulty Repair as necessary.
Blower motor faulty Check blower motor referring to “Blower Motor
Inspection in Section 7A”.