Suzuki SY413 Service Manual page 2699

6-1-100 ENGINE GENERAL INFORMATION AND DIAGNOSIS (G13/G16 ENGINE WITH WU TWC)
DTC P1600 SERIAL COMMUNICATION PROBLEM BETWEEN ECM AND TCM
(G16 WITH A/T)
CIRCUIT DESCRIPTION
The serial data line is pulled up to about 12 V by ECM and TCM transmits information to ECM through it by control-
ling its grounding.
TCM constantly sends information while ignition switch is ON as to whether judgement was made or not with re-
spect to all detectable DTCs as well as whether or not abnormality exists after judgement.
DTC DETECTING CONDITION
No signal inputted from TCM to ECM or check sum
error while engine running
DTC CONFIRMATION PROCEDURE
1) Turn ignition switch OFF.
2) Clear DTC with ignition switch ON.
3) Start engine and run it at idle for 1 min.
4) Select "DTC" mode on scan tool and check DTC.
POSSIBLE CAUSE
D "G / W" circuit open or short
D TCM power or ground circuit open.
D TCM malfunction
D ECM malfunction