Toyota Celica 2005 Repair Manual page 780

DTC P1645
CIRCUIT DESCRIPTION
ECM receives the operating condition (ON/OFF) of A/C from A/C ECU and it also receives the electrical load
information from the body ECU.
ECM uses the information to control the engine (idle up, etc.).
DTC No.
Condition (a) or (b) continues for 3.0 sec.
P1645 (a) No communication from body ECU
(b) No communication from A/C ECU
INSPECTION PROCEDURE
HINT:
Read freeze frame data using the hand−held tester or the OBD II scan tool. Freeze frame data records the
engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help deter-
mine if the vehicle was running or stopped, if the engine was warmed up or not, if the air−fuel ratio was lean
or rich, as well as other data from the time when a malfunction occurred.
Perform troubleshooting the Multiplex Communication System (See page DI−1184).
2005 CELICA (RM1131U)
DIAGNOSTICS
Body ECU Malfunction
DTC Detecting Condition
− ENGINE (2ZZ−GE)
S Body ECU
S A/C ECU
S Communication bus
779
Trouble Area
DI−581
DI1MG−13