DTC B2402 Transistor Relay Overload Malfunction: Description

The electric current flowing in the transistor inside the Junction Block is examined by the Multiplex Network Rear ECU (Luggage room Junction Block ECU). When excessive current is detected, DTC B2402 is output. When overheating occurs prior to an excessive current, the ECU cuts off the current in the transistor to prevent it from being damaged and outputs DTC B2403. Normally, turning off the engine switch clears DTC. However, if an excessive current is detected frequently (9 times or more), DTC may not be cleared. When this happens, disconnect the cable from the negative (-) battery terminal to clear DTC.

1. READ VALUE OF INTELLIGENT TESTER 
   1. Connect the intelligent tester to the DLC3.
   2. Turn the engine switch on (IG) and press the intelligent tester main switch on.
   3. Select the items below in the DATA LIST, and read the displays on the intelligent tester.

      MULTIPLEX NETWORK REAR ECU (LUGGAGE ROOM JUNCTION BLOCK): 

      MULTIPLEX NETWORK REAR ECU (LUGGAGE ROOM JUNCTION BLOCK) DATA LIST
      
      

      Item	Measurement Item / Display (Range)	Normal Condition	Diagnostic Note
      TAIL LGT Tr	Taillight Transistor / ON or OFF	ON: Light control switch TAIL or HEAD position OFF: Light control switch other than HEAD position	-
      STOP LIGHT Tr	Stop light Transistor / ON or BREAK	ON: Brake pedal depressed OFF: Brake pedal released	-
      H-M STOP LGT Tr	High mount stop light Transistor / ON or BREAK	ON: Brake pedal depressed BREAK: Brake pedal released	-
      LICENSE LGT Tr	License LGT Transistor / ON or BREAK	ON: Light control switch TAIL position BREAK: Light control switch other than HEAD position	-

      OK : Condition sign can be displayed. 

   NG : Go to step 2 

   OK : NORMAL OPERATION, NOT A MALFUNCTION 

2. CHECK WIRE HARNESS (MULTIPLEX NETWORK REAR ECU (LUGGAGE ROOM JUNCTION BLOCK ECU)) 
   1. Check each circuit in the table below.
      CIRCUIT REFERENCE FOR INSPECTION
      
      

      Suspected Area	See procedure
      Taillight	TAILLIGHT
      Stop light	STOP LIGHT
      Back-up light	BACK-UP LIGHT

      OK : Each light illuminates. 

   OK : REPLACE MULTIPLEX NETWORK REAR ECU (LUGGAGE ROOM JUNCTION BLOCK ECU)