DTC B1200: MPX Body ECU Stop: Procedure

WARNING: This page is about a different car, the 2011 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.

CHECK HARNESS AND CONNECTOR (BODY ECU - BATTERY AND BODY GROUND)

Disconnect the IA and IF ECU connector.

Measure the voltage according to the value(s) in the table below.

Voltage

Tester Connection	Condition	Specified Condition
IA-1 (BATB) - Body ground	Always	10 to 14 V

Measure the resistance according to the value(s) in the table below.

Resistance

Tester Connection	Condition	Specified Condition
IF-10 (GND1) - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to next step

CHECK RESISTANCE OF COMMUNICATION LINE

Disconnect the D6, D13, IR and E30 ECU connectors.

Measure the resistance according to the value(s) in the table below.

Resistance

Tester Connection	Condition	Specified Condition
IR-9 (MPX1) - E30-33 (MPX+)	Always	Below 1 Ω
D6-21 (MPX2) - D13-6 (MPX1)	Always	Below 1 Ω

Result

Result	Proceed to
Both are OK	A
One is OK	B
Both are NG	C

B → REPLACE BODY ECU AND REPAIR OR REPLACE HARNESS OR CONNECTOR

C → REPAIR OR REPLACE HARNESS OR CONNECTOR

A → REPLACE BODY ECU