Toyota Tundra Service Manual: Terminals Of Ecu

Toyota Tundra Service Manual / Brake / Brake Control / Dynamic Control Systems / Trailer Brake Control System / Terminals Of Ecu

TERMINALS OF ECU

1. CHECK TRAILER BRAKE CONTROL ECU (BRAKE CONTROL WITH BRACKET RELAY)

(a) Disconnect the J172 trailer brake control ECU (brake control with bracket relay) connector and measure the voltage or resistance on the wire harness side.

Text in Illustration

Front view of wire harness connector

(to Trailer Brake Control ECU [Brake Control with Bracket Relay])

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
J172-2 (+B) - J172-20 (GND)	B - W-B	Power supply (from battery)	Always	11 to 14 V
J172-5 (CANH) - J172-14 (CANL)	B - W	CAN communication line	Ignition switch off	54 to 69 Ω
J172-13 (IG) - J172-20 (GND)	V - W-B	IG power source	Ignition switch ON	11 to 14 V
J172-20 (GND) - Body ground	W-B - Body ground	Trailer brake control ECU (brake control with bracket relay) ground	Always	Below 1 Ω

(b) Connect the J172 trailer brake control ECU (brake control with bracket relay) connector.

(c) Measure the voltage and resistance according to the value(s) in the table below. If the result is not as specified, the ECU may be malfunctioning.

Text in Illustration

Component without harness connected

(Trailer Brake Control ECU [Brake Control with Bracket Relay])

HINT:

Measure the values on the wire harness side while the connector is connected.

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
J172-1 (BRK) - J172-20 (GND)	L - W-B	Trailer brake output	Ignition switch ON No trailer brake control	Below 3.5 V
J172-1 (BRK) - J172-20 (GND)	L - W-B	Trailer brake output	Ignition switch ON Manual trailer brake output slider operated to maximum position (100%)	11 to 14 V
J172-6 (GA-) - J172-20 (GND)	BR - W-B	GAIN (-) selection button input	Ignition switch ON GAIN (-) selection button OFF	11 to 14 V
J172-6 (GA-) - J172-20 (GND)	BR - W-B	GAIN (-) selection button input	Ignition switch ON GAIN (-) selection button ON	Below 1 V
J172-7 (SRW2) - J172-20 (GND)	Y - W-B	Manual trailer brake output slider adjustable resistor 2 input	Ignition switch ON No trailer brake control	4.5 to 5.5 V
J172-7 (SRW2) - J172-20 (GND)	Y - W-B		Ignition switch ON Manual trailer brake output slider operated to maximum position (100%)	0 to 1.0 V
J172-9 (SRW1) - J172-20 (GND)	R - W-B	Manual trailer brake output slider adjustable resistor 1 input	Ignition switch ON No trailer brake control	0 to 1.0 V
J172-9 (SRW1) - J172-20 (GND)	R - W-B		Ignition switch ON Manual trailer brake output slider operated to maximum position (100%)	4.5 to 5.5 V
J172-11 (SRRT) - J172-20 (GND)	G - W-B	Manual trailer brake output slider GND terminal	Ignition switch ON	0 to 0.5 V
J172-15 (GA+) - J172-20 (GND)	R - W-B	GAIN (+) selection button input	Ignition switch ON GAIN (+) selection button OFF	11 to 14 V
J172-15 (GA+) - J172-20 (GND)	R - W-B	GAIN (+) selection button input	Ignition switch ON GAIN (+) selection button ON	Below 1 V
J172-16 (SRF)- J172-20 (GND)	P - W-B	Manual trailer brake output slider power supply output	Ignition switch ON	4.0 to 6.43 V
J172-18 (SRR) - J172-20 (GND)	L - W-B	Manual trailer brake output slider upstream power supply reference power supply monitor	Ignition switch ON	4.0 to 6.43 V

System Diagram

Control Module Communication Bus "A" Off (U0073,U0123,U0129,U0155)

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Toyota Tundra Service Manual: Terminals Of Ecu

System Diagram

Control Module Communication Bus "A" Off (U0073,U0123,U0129,U0155)

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