Toyota 4Runner: Lost Communication with ECM (C1437)

Toyota 4Runner Service Manual / Brake / Brake Control / Dynamic Control Systems / Vehicle Stability Control System(for Hydraulic Brake Booster) / Lost Communication with ECM (C1437)

DESCRIPTION

The skid control ECU receives signals from the ECM via the CAN communication system.

DTC Code	DTC Detection Condition	Trouble Area
C1437	When the IG1 terminal voltage is 10 V or higher and the vehicle speed is 15 km/h (9 mph) or more, data cannot be sent from the ECM for 2 seconds or more.	Engine control system CAN communication system Master cylinder solenoid (Skid control ECU)

CAUTION / NOTICE / HINT

NOTICE:

When replacing the master cylinder solenoid, perform calibration (See page ).

PROCEDURE

1.	CHECK HARNESS AND CONNECTOR (MOMENTARY INTERRUPTION)

(a) Using the Techstream, check for any momentary interruption in the wire harness and connector corresponding to the DTC (See page
).

ABS/VSC/TRAC

Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
EFI Communication Open	EFI communication open detection/ Error or Normal	Normal	-

OK:

Normal (there are no momentary interruptions).

HINT:

Perform the above inspection before removing the sensor and connector.

GO TO STEP 3

2.	RECONFIRM DTC

(a) Clear the DTCs (See page ).

(b) Turn the ignition switch off.

(d) Drive the vehicle at a speed of 15 km/h (9 mph) or more for 10 seconds or more.

(e) Check that no CAN communication system DTC is output (See page ).

(f) Check if the same DTC is output (See page
).

Result

Result	Proceed to
DTC C1437 is not output	A
DTC C1437 is output	B
CAN communication system DTC is output	C

USE SIMULATION METHOD TO CHECK

GO TO ENGINE CONTROL SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING)

GO TO CAN COMMUNICATION SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING)

3.	REPAIR OR REPLACE HARNESS OR CONNECTOR (SKID CONTROL ECU - ECM)

(a) Turn the ignition switch off.

(b) Repair or replace the harness or connector.

(d) Check that there is no momentary interruption.

4.	RECONFIRM DTC

(a) Clear the DTCs (See page ).

(b) Turn the ignition switch off.

(d) Drive the vehicle at a speed of 15 km/h (9 mph) or more for 10 seconds or more.

(e) Check that no CAN communication system DTC is output (See page ).

(f) Check if the same DTC is output (See page
).

Result

Result	Proceed to
DTC C1437 is not output	A
DTC C1437 is output	B
CAN communication system DTC is output	C

END

REPLACE MASTER CYLINDER SOLENOID

GO TO CAN COMMUNICATION SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING)

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