Last Modified: 7-3-2017 6.8:8.0.40 Doc ID: RM000001EG5004X
Model Year Start: 2007 Model: LX470 Prod Date Range: [08/2006 -           ]
Title: CELLULAR COMMUNICATION: LEXUS LINK SYSTEM: 4-7; EMERGENCY, VOL+ or VOL- Button has Connection Error; 2007 MY LX470 [08/2006 -        ]

DTC

4-7

EMERGENCY, VOL+ or VOL- Button has Connection Error

DESCRIPTION

This DTC is output when one of the following occurs: 1) the mayday ECU assembly is malfunctioning; 2) the mayday switch assembly is malfunctioning; or 3) the wire harness between the mayday ECU assembly and the map light plate assembly is open or short.

DTC No.

DTC Detection Condition

Trouble Area

4 - 7

Communication or communication line is abnormal between mayday ECU and map light plate (mayday switch)
  • Mayday ECU assembly
  • Map light plate assembly
  • Mayday switch assembly
  • Wire harness

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1.

CHECK WIRE HARNESS (ECU - MAP LIGHT PLATE ASSEMBLY (MAYDAY SWITCH ASSEMBLY))

(a) Disconnect the M15 ECU connector.

(b) Disconnect the O4 map light plate connector.

(c) Measure the resistance of the wire harness side connectors.

Standard resistance:

Tester Connection

Specified Condition

M15-5 (SIG1) - O4-13 (SIG1)

Below 1 Ω

M15-12 (SIG-) - O4-9 (SIG-)

Below 1 Ω

M15-5 (SIG1) or O4-13 (SIG1) - Body ground

10 kΩ or higher

M15-12 (SIG-) or O4-9 (SIG-) - Body ground

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS AND CONNECTOR THEN CLEAR HISTORIC DTC

OK

2.

INSPECT MAYDAY SWITCH ASSEMBLY

(a) Remove the map light plate assembly.

(b) Remove the mayday switch assembly from the map light plate assembly.

(c) Measure the resistance of the switch when each switch is pressed.

Standard resistance:

Tester Connection

Switch Condition

Specified Condition

6 (SIG1) - 2 (SIG-)

EMERGENCY

305 to 313 Ω

6 (SIG1) - 2 (SIG-)

VOL+

812 to 831 Ω

6 (SIG1) - 2 (SIG-)

VOL-

1811 to 1848 Ω
NG

REPLACE MAYDAY SWITCH ASSEMBLY THEN CLEAR HISTORIC DTC

OK

3.

INSPECT MAP LIGHT PLATE ASSEMBLY

(a) Install the mayday switch assembly to the map light plate assembly.

(b) Measure the resistance of the switch when each switch is pressed.

Standard resistance:

Tester Connection

Switch Condition

Specified Condition

13 (SIG1) - 9 (SIG-)

EMERGENCY

305 to 313 Ω

13 (SIG1) - 9 (SIG-)

VOL+

812 to 831 Ω

13 (SIG1) - 9 (SIG-)

VOL-

1811 to 1848 Ω
NG

REPLACE MAP LIGHT PLATE ASSEMBLY THEN CLEAR HISTORIC DTC

OK

REPLACE MAYDAY ECU ASSEMBLY TOGETHER WITH MAYDAY BATTERY AND THEN PERFORM REGISTRATION