Toyota Tacoma (2015-2018) Service Manual: Wireless Door Lock Tuner Circuit Malfunction (B1242)

Toyota Tacoma (2015-2018) Service Manual / Door Lock / Wireless Door Lock Control System(w/ Smart Key System) / Wireless Door Lock Tuner Circuit Malfunction (B1242)

DESCRIPTION

The door control receiver is used to receive radio waves relating to the entry functions of the electrical key transmitter sub-assembly. The certification ECU (smart key ECU assembly) decodes the requested electrical key transmitter sub-assembly by identifying a key code based on the radio waves received via the door control receiver. The door control receiver receives a signal from the electrical key transmitter sub-assembly and sends signals to the main body ECU (multiplex network body ECU) through the certification ECU (smart key ECU assembly). The certification ECU (smart key ECU assembly) then sends a command, according to the requested operation, to each ECU (ex. if door lock operation is requested, the certification ECU (smart key ECU assembly) sends a door lock command to the main body ECU (multiplex network body ECU)).

DTC No.	DTC Detecting Condition	Trouble Area
B1242	Short in RDAM or CSEL to ground between the certification ECU (smart key ECU assembly) and the door control receiver. Short in RDAM or CSEL to ground when RCO (5 V) output from the ECU is off.	Wire harness or connector Door control receiver Certification ECU (Smart key ECU assembly)

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When replacing or inspecting the door control receiver and wire harness, do not change the position or length of the wire harness. If the wire harness is too close to the door control receiver, smart and wireless function performance may be affected.
Before performing the inspection, check that there are no problems related to the CAN communication system (See page ).
When replacing the door control receiver, read the transmitter IDs (tire pressure warning system) stored in the old ECU using the Techstream and write them down before removal (See page ).*
It is necessary to perform registration (See page ) of the transmitter IDs into the door control receiver if the door control receiver has been replaced.*
This DTC is not detected within 10 seconds after the engine switch turned to off from on (IG).
- *: w/ Tire Pressure Warning System

PROCEDURE

1.	CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

(a) Disconnect the door control receiver connector.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
T24-8 (+5) - T24-12 (GND)	Engine switch off, all doors closed and electrical key transmitter sub-assembly switch not pressed → electrical key transmitter sub-assembly switch pressed	Below 1 V → 4.5 to 5.5 V (Pulse generation)
T24-2 (DATA) - T24-12 (GND)	Engine switch off	11 to 14 V pulse generation at regular intervals

Tester Connection

Condition

Specified Condition

T24-8 (+5) - T24-12 (GND)

Engine switch off, all doors closed and electrical key transmitter sub-assembly switch not pressed → electrical key transmitter sub-assembly switch pressed

Below 1 V → 4.5 to 5.5 V

(Pulse generation)

T24-2 (DATA) - T24-12 (GND)

Engine switch off

11 to 14 V pulse generation at regular intervals

Standard Resistance:

Tester Connection	Condition	Specified Condition
T24-12 (GND) - Body ground	Always	Below 1 Ω

Text in Illustration

*a	Front view of wire harness connector (Door control receiver)

REPLACE DOOR CONTROL RECEIVER

2.	CHECK HARNESS AND CONNECTOR (DOOR CONTROL RECEIVER - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))

(a) Disconnect the certification ECU (smart key ECU assembly) connectors.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
C28-19 (CSEL) - T24-6 (CSEL)	Always	Below 1 Ω
C28-20 (RDAM) - T24-2 (DATA)	Always	Below 1 Ω
C28-18 (RCO) - T24-8 (+5)	Always	Below 1 Ω
C29-11 (E) - Body ground	Always	Below 1 Ω
T24-12 (GND) - Body ground	Always	Below 1 Ω
C28-19 (CSEL) or T24-6 (CSEL) - Body ground	Always	10 kΩ or higher
C28-22 (RDAM) or T24-2 (DATA) - Body ground	Always	10 kΩ or higher
C28-18 (RCO) or T24-8 (+5) - Body ground	Always	10 kΩ or higher

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

REPAIR OR REPLACE HARNESS OR CONNECTOR

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