2005 SUZUKI SWIFT Inspection of ecm

Downloaded from www.Manualslib.com manuals search engine Automatic Transmission/Transaxle: 5A-73
DTC P1777: TCM Lost Communication with ECM (Reception Error)S7RS0B5104040
Wiring Diagram
Refer to “DTC P1774: CAN Communication Bus Off”
DTC Detecting Condition and Trouble Area
DTC Confirmation Procedure1) Connect scan tool to DLC with ignition switch OFF.
2) Clear DTC.
3) Start engine and run it for 1 min. or more.
4) Check DTC.
DTC Troubleshooting
NOTE
Upon completion of inspection and repair work, perform “DTC Confirmation Procedure:” and confirm
that the trouble has been corrected.

DTC detecting condition Trouble area
Reception error of communication data fo r ECM is detected more than specified
time continuously. •ECM
•TCM
• CAN circuit
Step
Action YesNo
1 Was “A/T System Check” performed? Go to Step 2.Go to “A/T System
Check”.
2 Control module connector check
1) Check connection of connectors of all control modules
communicating by means of CAN.
2) Recheck DTC.
Is there DTC P1777? Go to Step 3.
Intermittent trouble.
Check for intermittent
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 DTC P1674? Go to “DTC P1674:
CAN Communication
(Bus Off Error) in
Section 1A”.
Check ECM power and
ground circuit. If circuit
is OK, CAN
communication circuit
between ECM and ABS
hydraulic unit / control
module is open circuit.
4 CAN communication circuit check
1) Turn ignition switch to OFF position.
2) Disconnect connectors of all control modules
communicating by means of CAN.
3) Check CAN communication circuit between control modules for open, short and high resistance.
Is each CAN communication circuit in good condition? Check TCM power and
ground circuit. If circuit
is OK, substitute a
known-good TCM and
recheck.
Repair circuit.

Downloaded from www.Manualslib.com manuals search engine 5A-74 Automatic Transmission/Transaxle:
DTC P1778: TCM Lost Communication with BCM (Reception Error)S7RS0B5104041
Wiring Diagram
Refer to “DTC P1774: CAN Communication Bus Off”.
DTC Detecting Condition and Trouble Area
DTC Confirmation Procedure
1) Connect scan tool to DLC with ignition switch OFF.
2) Clear DTC.
3) Start engine and run it for 1 min. or more.
4) Check DTC.
DTC Troubleshooting
NOTE
Upon completion of inspection and repair work, perform “DTC Confirmation Procedure:” “DTC
Confirmation Procedure” and confirm that the trouble has been corrected.

DTC detecting condition Trouble area
Reception error of communication data fo r BCM is detected more than specified
time continuously. •ECM
•TCM
•BCM
• ABS control module
• CAN circuit
Step
Action YesNo
1 Was “A/T System Check” performed? Go to Step 2.Go to “A/T System
Check”.
2 Control module connector check
1) Check connection of connectors of all control modules
communicating by means by means of CAN.
2) Recheck DTC.
Is there DTC P1778? Go to Step 3.
Intermittent trouble.
Check for intermittent
referring to “Intermittent
and Poor Connection
Inspection in Section
00”.
3 DTC check in BCM (bus off)
1) Check BCM for DTC referring to “DTC Check in Section
10B”.
Is there DTC U1073? Go to “DTC U1073 (No.
1073): Control Module
Communication Bus Off
in Section 10B”.
Go to Step 4.
4 DTC check in ABS control module
1) Check ABS control module for DTC referring to “DTC
Check in Section 4E”.
Is there DTC U1100? Go to “DTC U1100: Lost
Communication with
ECM (Reception Error)
in Section 4E”.
Go to Step 5.
5 DTC check in ECM
1) Check ECM for DTC referring to “DTC Check in Section
1A”.
Is there DTC P1678? Check BCM power and
ground circuit. If circuit
is OK, substitute a
known-good BCM and
recheck.Go to Step 6.
6 CAN communication circuit check
1) Turn ignition switch to OFF position.
2) Disconnect connectors of all control modules
communicating by means of CAN.
3) Check CAN communication circuit between control modules for open, short and high resistance.
Is each CAN communication circuit in good condition? Check TCM power and
ground circuit. If circuit
is OK, substitute a
known-good TCM and
recheck.
Repair circuit.

Downloaded from www.Manualslib.com manuals search engine 6C-12 Power Assisted Steering System:
Scan Tool Data Definitions
Battery Voltage
This parameter indicates battery positive voltage.
TQS Power Supply (Torque Sensor Power Supply, V)
This parameter indicates the power supply voltage which
the P/S control module supplies to the torque sensor.
TQS Main Torque (Torque Sensor Main Torque, N ⋅m)
The torque sensor is installed to detect the steering force
and the steering directio n. It consists of two
potentiometers and the main torque sensor is one of
these.
TQS Sub Torque (Torque Sensor Sub Torque, N ⋅m)
The torque sensor is installed to detect the steering force
and the steering directio n. It consists of two
potentiometers and the sub-torque sensor is one of
these. Its output characteristics are compared with those
of the main torque sensor.
Assist Torque (N ⋅m)
This parameter is an internal parameter of the P/S
control module. It is obtained by computing the torque
sensor input signal. Motor Control (Motor Control Current, A)
Based on the input signal, the P/S control module
determines the assist amount
and controls the current to
the motor suitable for that a ssist amount. This parameter
indicates that control value.
Motor Monitor (Motor Monitor Current, A)
This parameter indicates the actually measured value of
the current flowing to the motor. The motor circuit
condition is diagnosed by co mparing this parameter with
“Motor Control” parameter described previously.
Vehicle Speed (km/h, MPH)
Vehicle speed signal is fed from BCM. P/S control
module determines the amount of power assist based on
this vehicle speed signal and the torque sensor signal.
Engine Speed (rpm)
Engine speed signal is fed from the ECM so that it can
be used for trouble diagnos is of the electric power
steering system.
Motor Volt (V)
This parameter indicates the voltage between motor
terminals.
Ignition switch (ON, OFF)
This parameter indicates the condition of the power
supply through the ignition switch.
Visual InspectionS7RS0B6304007
Visually check the following pats and system.
P/S System Symptom DiagnosisS7RS0B6304008
This section describes trouble diagnosis of the P/S system parts whose trouble is not indicated by the on-board
diagnostic system (self-diagnostic functi on). When no malfunction is indicated by the on-board diagnostic system
(self-diagnosis function) and those stee ring basic parts as described in “Steering Symptom Diagnosis in Section 6A”
are all in good condition, check the following power steer ing system parts which may be a possible cause for each
symptom of the steering. Inspection Item Referring section
Battery Level, leakage, color “Batte ry Description in Section 1J”
Connectors of electric wire
harness Disconnection friction “Intermittent and Poor
Connection Inspection in Section 00”
Fuses Burning “Cautions in Body Electric al System Servicing in Section 9A”
Parts Installation, damage
Other parts that can be checked visually
Condition Possible cause Correction / Reference Item
Steering wheel feels
heavy (Perform “Steering
Force Check” before
diagnosis.) Steering wheel installed improperly
(twisted)
Install steering wheel correctly.
Poor performance of torque sensor Check torque sensor referring to “Torque
Sensor and Its Circuit Inspection”.
Poor performance of P/S motor Check motor referring to “P/S Motor and Its
Circuit Inspection”.
Steering gear case assembly faulty Replace.
Poor performance of vehicle speed
signal from ECM Check vehicle speed signal circuit referring to
“DTC C1121 / C1123 / C1124: VSS Circuit
Failure”.

Downloaded from www.Manualslib.com manuals search engine Power Assisted Steering System: 6C-13
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)

Downloaded from www.Manualslib.com manuals search engine Power Assisted Steering System: 6C-27
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.

Downloaded from www.Manualslib.com manuals search engine Power Assisted Steering System: 6C-29
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 — —— —

Downloaded from www.Manualslib.com manuals search engine Power Assisted Steering System: 6C-37
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