Dtc P1778: Tcm Lost Communication With Bcm (Reception Error) - Suzuki Swift Sport 2004 Service & Repair Manual

5A-74 Automatic Transmission/Transaxle:

DTC P1778: TCM Lost Communication with BCM (Reception Error)

Wiring Diagram
Refer to "DTC P1774: CAN Communication Bus Off".
DTC Detecting Condition and Trouble Area
Reception error of communication data for BCM is detected more than specified
time continuously.
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.
Step
1 Was "A/T System Check" performed?
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?
3 DTC check in BCM (bus off)
1) Check BCM for DTC referring to "DTC Check in Section
10B".
Is there DTC U1073?
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?
5 DTC check in ECM
1) Check ECM for DTC referring to "DTC Check in Section
1A".
Is there DTC P1678?
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?
DTC detecting condition
Action
• ECM
• TCM
• BCM
• ABS control module
• CAN circuit
Yes
Go to Step 2.
Go to Step 3.
Go to "DTC U1073 (No.
1073): Control Module
Communication Bus Off
in Section 10B".
Go to "DTC U1100: Lost
Communication with
ECM (Reception Error)
in Section 4E".
Check BCM power and
ground circuit. If circuit
is OK, substitute a
known-good BCM and
recheck.
Check TCM power and
ground circuit. If circuit
is OK, substitute a
known-good TCM and
recheck.
S7RS0B5104041
Trouble area
No
Go to "A/T System
Check".
Intermittent trouble.
Check for intermittent
referring to "Intermittent
and Poor Connection
Inspection in Section
00".
Go to Step 4.
Go to Step 5.
Go to Step 6.
Repair circuit.