Toyota Celica 2005 Repair Manual page 477

DI−278
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 these 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, and other data from the time the malfunction occurred.
Perform troubleshooting the Multiplex Communication System (See page BE−2).
2005 CELICA (RM1131U)
DIAGNOSTICS
Body ECU Malfunction
DTC Detecting Condition
− ENGINE (1ZZ−FE)
S Body ECU
S A/C ECU
S Communication bus
476
Trouble Area
DI1MG−12