DTC B1242: Wireless Door Lock Tuner Circuit Malfunction [02/2014 - 11/2016]: Procedure

1. Disconnect the M25 electrical key and tire pressure monitoring system receiver assembly connector.
2. Measure the voltage and resistance and check for pulses according to the value(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a

   Component with harness connected (Certification ECU (Smart Key ECU Assembly))

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   -

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   F9-3 (RDAM) - F11-1 (E)	always	11 to 14 V
   F9-1(RCO) - F11-1 (E)	always	Below 1 V → 4.5 to 5.5 V pulse generation at regular intervals

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   F11-1 (E) - Body ground	Always	Below 1 Ω

   Result	Proceed to
   NG	A
   OK	B

Result: 

B 

REPLACE ELECTRICAL KEY AND TIRE PRESSURE MONITORING SYSTEM RECEIVER ASSEMBLY: 

Refer to REMOVAL [02/2014 - ] .

Result: 

A 

See step  2

1. Disconnect the F9 certification ECU (smart key ECU assembly) connector.
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   F9-3 (RDAM) - M25-9 (DATA)	Always	Below 1 Ω
   F9-1 (RCO) - M25-10 (+5)	Always	Below 1 Ω
   M25-12 (GND) - Body ground	Always	Below 1 Ω
   M25-9 (DATA) or F9-3 (RDAM) - Body ground	Always	10 kΩ or higher
   M25-10 (+5) or F9-1 (RCO) - Body ground	Always	10 kΩ or higher

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY): 

Refer to REMOVAL [02/2014 - 11/2016] .

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR