Toyota Yaris: Charging System / Lost Communication with Alternator Missing Message (P161A87)

Toyota Yaris XP210 (2020-2025) Reapir and Service Manual / Power Source & Network / G16e-gts (battery / Charging) / Charging System / Lost Communication with Alternator Missing Message (P161A87)

DESCRIPTION

The ECM communicates with the generator assembly via LIN communication. If a LIN communication error is detected, the ECM stores this DTC.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Note
P161A87	Lost Communication with Alternator Missing Message	Generator assembly or ECM communication stops for approximately 17 minutes or more with the ignition switch ON (1 trip detection logic)	Wire harness or connector Generator assembly ECM	Comes on	SAE Code: P161A

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Note

P161A87

Lost Communication with Alternator Missing Message

Generator assembly or ECM communication stops for approximately 17 minutes or more with the ignition switch ON

(1 trip detection logic)

Wire harness or connector
Generator assembly
ECM

Comes on

SAE Code: P161A

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following inspection procedure.
Before replacing the ECM, refer to Service Bulletin.

PROCEDURE

1.	CHECK CHARGING SYSTEM

Click here

REPAIR OR REPLACE CHARGING SYSTEM

2.	CHECK HARNESS AND CONNECTOR (ECM - GENERATOR ASSEMBLY)

(a) Disconnect the D104 ECM connector.

(b) Disconnect the D53 generator assembly connector.

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

Standard Resistance (Check for Open):

Tester Connection	Condition	Specified Condition
O68-2 (LIN) or D53-2 (LIN) - D104-62 (LIN)	Always	Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection	Condition	Specified Condition
O68-2 (LIN), D53-2 (LIN) or D104-62 (LIN) - Body ground	Ignition switch off (while LIN communication stopped)	10 kΩ or higher

Tester Connection

Condition

Specified Condition

O68-2 (LIN), D53-2 (LIN) or D104-62 (LIN) - Body ground

Ignition switch off

(while LIN communication stopped)

10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

CLEAR DTC

(a) Check for DTCs using the GTS, and then write them down.

Powertrain > Engine > Trouble Codes

(b) Clear the DTCs.

Powertrain > Engine > Clear DTCs

4.	CHECK DTC OUTPUT

(a) Start the engine.

(b) Allow the engine to idle for approximately 17 minutes or more.

Powertrain > Engine > Trouble Codes

Result	Proceed to
Only P161A87 is output	A
P161A87 and P162B87 are output	B
DTCs are not output	C

REPLACE GENERATOR WITH REGULATOR ASSEMBLY

REPLACE ECM

CHECK FOR INTERMITTENT PROBLEMS

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