Toyota Tundra Service Manual: Terminals Of Ecu

TERMINALS OF ECU

1. CHECK RADIO AND DISPLAY RECEIVER ASSEMBLY

(a) Disconnect the J137 and J139 radio and display receiver assembly connectors.

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

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specification
J137-3 (ACC1) - J137-7 (GND1)	GR - BR	Power source (ACC)	Ignition switch off	Below 1 V
J137-3 (ACC1) - J137-7 (GND1)	GR - BR	Power source (ACC)	Ignition switch ACC	11 to 14 V
J137-4 (+B1) - J137-7 (GND1)	LA-SB - BR	Power source (+B)	Always	11 to 14 V
J137-7 (GND1) - Body ground	BR - Body ground	Ground	Always	Below 1 Ω
J139-1 (IG) - J137-7 (GND1)	BE - BR	Power source (IG)	Ignition switch off	Below 1 V
J139-1 (IG) - J137-7 (GND1)	BE - BR	Power source (IG)	Ignition switch ON	11 to 14 V

(d) Measure the voltage and waveform according to the value(s) in the table below.

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specification
J139-2 (REV) - J137-7 (GND1)	Y - BR	Reverse signal	Ignition switch ON, shift lever in R	7.5 to 14 V
J139-2 (REV) - J137-7 (GND1)	Y - BR	Reverse signal	Ignition switch ON, shift lever not in R	Below 1 V
J140-11 (CA+) - J140-23 (CGND)	B - Shielded	Power source	Ignition switch ACC	5.5 to 7.05 V
J140-12 (V+) - J140-24 (V-)	R - W	Display signal	Ignition switch ON	Pulse generation (See waveform 1)
J140-12 (V+) - J140-24 (V-)	R - W	Display signal	Ignition switch ON, screen blacked out by covering camera lens	Pulse generation (See waveform 2)
J140-23 (CGND) - Body ground	Shielded - Body ground	Shielded ground	Always	Below 1 Ω

(e) Using an oscilloscope, check the waveform.

*a	Waveform 1	*b	Waveform 2
*c	Synchronization Signal	*d	Video Waveform

(1) Waveform 1

Measurement Condition

HINT:

The video waveform changes according to the image sent by the television camera assembly.

(2) Waveform 2

Measurement Condition

Item	Content
Terminal No. (Symbol)	J140-12 (V+) - J140-24 (V-)
Tool Setting	0.2 V/DIV., 50 μs/DIV.
Condition	Ignition switch ON, screen blacked out by covering camera lens

HINT:

The video waveform changes according to the image sent by the television camera assembly.

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Toyota Tundra Owners Manual