CELLULAR COMMUNICATION: LEXUS LINK SYSTEM: TERMINALS OF ECU (2008 LX570)

TERMINALS OF ECU

1. CHECK TELEPHONE ECU ASSEMBLY

(a) Arrangement of telephone ECU assembly terminal.

Terminal No. (Symbol)	Wiring Color	Terminal Description
P2-1 (+B)	G	Vehicle battery power supply
P2-2 (SPO+)	W	Audio speaker output +
P2-3 (SPO-)	B	Audio speaker output -
P2-7 (MCVD)	Y	Microphone power supply
P2-8 (MCI+)	G	Microphone input signal +
P2-9 (MCI-)	R	Microphone input signal -
P2-10 (SPI+)	W	Sound signal
P2-11 (SPI-)	B	Sound signal
P2-12 (E)	W-B	Ground
P2-13 (IG2)	B	IG power supply
P2-14 (ACC)	GR	ACC power supply
P2-16 (GSW)	L	Airbag signal
P2-17 (MCO+)	G	Microphone output
P2-18 (MCO-)	R	Audio ground
P2-19 (SGND)	Shielded	Shield ground
P2-21 (HFOF)	B	Phone mute
P2-22 (MUTE)	B	Radio mute
P2-23 (MPX1)	B	MPX line
P3-2 (BBI+)	R	Mayday battery input
P3-4 (IND1)	L	Red LED output
P3-5 (SIG1)	W	Mayday switch input
P3-9 (BBI-)	L	Mayday battery input
P3-11 (IND2)	P	Green LED output
P3-12 (SIG-)	L	Mayday switch ground
P3-13 (SIG2)	W	Mayday switch input
P3-15 (SIL)	R	DLC3 line

(b) Check telephone ECU assembly.

(1) Disconnect the P2 and P3 ECU connectors.

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

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
P2-12 (E) - Body ground	W-B - Body ground	Ground	Always	Below 1 Ω
P2-1 (+B) - Body ground	G - Body ground	Vehicle battery power supply	Always	11 to 14 V
P2-14 (ACC) - Body ground	GR - Body ground	ACC power supply	Engine switch on (ACC)	11 to 14 V
P2-13 (IG2) - Body ground	B - Body ground	IG power supply	Engine switch on (IG)	11 to 14 V
P2-10 (SPI+) - P2-12 (E)	W - W-B	Sound signal	Audio system playing	Waveform synchronized with sound is output
P2-11 (SPI-) - P2-12 (E)	B - W-B	Sound signal	Audio system playing	Waveform synchronized with sound is output
P2-21 (HFOF) - P2-12 (E)	B - W-B	Phone mute	Engine switch on (IG)	3.3 to 5.0 V
P2-22 (MUTE) - P2-12 (E)	B - W-B	Radio mute	Engine switch on (IG)	3.3 to 5.0 V
P3-2 (BBI+) - P3-9 (BBI-)	R - L	Non-rechargeable back-up	Always	9 to 16 V
P3-5 (SIG1) - P3-12 (SIG-)	W - L	Mayday switch input	Engine switch off, all buttons not pushed	4.4 to 5.0 kΩ
P3-13 (SIG2) - P3-12 (SIG-)	W - L	Mayday switch input	Engine switch off, all buttons not pushed	4.4 to 5.0 kΩ

If the result is not as specified, there may be a malfunction on the wire harness side.

(3) Disconnect the B telephone antenna (cellular phone) connector (color: blue) from the ECU.

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

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
B-1 (SIGNAL) - Body ground	B - Body ground	Telephone signal input/output	Always	4 to 11 kΩ

If the result is not as specified, there may be a malfunction on the antenna side.

2. CHECK BUS BUFFER ECU

(a) Disconnect the P5 ECU connector.

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

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
P5-4 (GND) - Body ground	W-B - Body ground	Ground	Always	Below 1 Ω
P5-3 (+B) - Body ground	G - Body ground	Battery power supply	Always	11 to 14 V

If the result is not as specified, there may be a malfunction on the wire harness side.

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

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
P5-5 (S1) - P5-4 (GND)	B - W-B	MPX line	Always	Pulse generation

If the result is not as specified, the ECU may have a malfunction.