Last Modified: 7-3-2017 6.8:8.0.40 Doc ID: RM000001EG2004X
Model Year Start: 2007 Model: LX470 Prod Date Range: [08/2006 -           ]
Title: CELLULAR COMMUNICATION: LEXUS LINK SYSTEM: 4-4; SERVICES, PHONE or PTT Button Stuck; 2007 MY LX470 [08/2006 -        ]

DTC

4-4

SERVICES, PHONE or PTT Button Stuck

DESCRIPTION

This DTC is output when one of the following occurs: 1) the mayday ECU assembly is malfunctioning; or 2) the mayday switch assembly is malfunctioning.

DTC No.

DTC Detection Condition

Trouble Area

4 - 4

Communication is abnormal between mayday ECU and map light plate (mayday switch)
  • Mayday ECU assembly
  • Map light plate assembly
  • Mayday switch assembly

INSPECTION PROCEDURE

PROCEDURE

1.

CHECK MAYDAY SWITCH ASSEMBLY

(a) Check that the mayday switch assembly is not stuck by pressing the switch several times.

(b) Check for DTC again.

OK:

Current DTC 4-4 is not output.

OK

CLEAR HISTORIC DTC

NG

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

7 (SIG2) - 2 (SIG-)

SERVICES

305 to 313 Ω

7 (SIG2) - 2 (SIG-)

PHONE

812 to 831 Ω

7 (SIG2) - 2 (SIG-)

PTT

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

14 (SIG2) - 9 (SIG-)

SERVICES

305 to 313 Ω

14 (SIG2) - 9 (SIG-)

PHONE

812 to 831 Ω

14 (SIG2) - 9 (SIG-)

PTT

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