DTC P1645 Gateway ECU Malfunction: Description

The ECM receives the operating condition signal (ON/OFF) of the A/C from A/C ECU, and it also receives the electrical load information from the gateway ECU.

The ECM uses these information to control the engine (idle up, etc.).

DTC REFERENCE

DTC No.	DTC Detection Condition	Trouble Area
P1645	Condition (a) or (b) continues for 10 seconds or more: No communication from body ECU No communication from A/C ECU	Gateway ECU A/C ECU Communication bus

Troubleshoot the Multiplex Communication System (See HOW TO PROCEED WITH TROUBLESHOOTING ).

HINT:

Read freeze frame data using the intelligent tester or the OBD ll scan tool. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.