Lexus NX manuals

Lexus NX: Wireless Door Lock Tuner Circuit Malfunction (B1242)

Lexus NX Service Manual / Vehicle Interior / Door Lock / Wireless Door Lock Control System / Wireless Door Lock Tuner Circuit Malfunction (B1242)

DESCRIPTION

The door control receiver is used to receive radio waves related 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 operation 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). (ex. if a 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.

Detection Item

DTC Detection Condition

Trouble Area

B1242

Wireless Door Lock Tuner Circuit Malfunction
  • Short in RDAM to ground between the certification ECU (smart key ECU assembly) and door control receiver.
  • Short in CSEL to ground between the certification ECU (smart key ECU assembly) and door control receiver.
  • Short in RDAM to ground when RCO (5 V) output from the ECU is off.
  • 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, entry and wireless function performance may be affected.
  • This DTC is not stored within 10 seconds of the power switch being turned from on (IG) to off.
  • The wireless door lock control system uses the CAN communication system. Inspect the communication function by following How to Proceed with Troubleshooting. Troubleshoot the wireless door lock control system after confirming that the communication system is functioning properly.

    Click here

  • 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.

    Click here

  • It is necessary to perform initialization ( ) after registration ( ) of the transmitter IDs into the door control receiver if the door control receiver has been replaced.
  • If the certification ECU (smart key ECU assembly) is replaced, refer to the Smart Access System with Push-button Start (for Entry Function).

    Click here

PROCEDURE

1.

CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

(a) Disconnect the door control receiver connector.

*a

Front view of wire harness connector

(to Door Control Receiver)

(b) Check for pulses and voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection

Condition

Specified Condition

P11-10 (+5) - Body ground
Procedure:
  1. Power switch off
  2. Electrical key transmitter sub-assembly brought outside detection area but kept inside wireless function operational area
  3. Lock or unlock switch of electrical key transmitter sub-assembly not pressed → pressed

Pulse generation

P11-6 (CSEL) - Body ground
Procedure:
  1. Power switch off
  2. All doors closed

Below 1 V → Pulse generation

P11-9 (DATA) - Body ground
Procedure:
  1. Power switch off
  2. All doors locked
  3. Electrical key transmitter sub-assembly not inside vehicle
  4. Electrical key transmitter sub-assembly brought outside detection area but kept inside wireless function operational area
  5. Lock or unlock switch of electrical key transmitter sub-assembly not pressed → pressed

Pulse generation
NG

REPLACE DOOR CONTROL RECEIVER

OK

2.

CHECK HARNESS AND CONNECTOR (DOOR CONTROL RECEIVER - CERTIFICATION ECU [SMART KEY ECU ASSEMBLY] AND BODY GROUND)

(a) Disconnect the I52 and I53 certification ECU (smart key ECU assembly) connectors.

(b) Disconnect the P11 door control receiver connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

I52-19 (CSEL) - P11-6 (CSEL)

Always

Below 1 Ω

I52-20 (RDAM) - P11-9 (DATA)

Always

Below 1 Ω

I52-18 (RCO) - P11-10 (+5)

Always

Below 1 Ω

I53-11 (E) - Body ground

Always

Below 1 Ω

P11-12 (GND) - Body ground

Always

Below 1 Ω

I52-19 (CSEL) or P11-6 (CSEL) - Body ground

Always

10 kΩ or higher

I52-20 (RDAM) or P11-9 (DATA) - Body ground

Always

10 kΩ or higher

I52-18 (RCO) or P11-10 (+5) - Body ground

Always

10 kΩ or higher
OK

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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