DTC 4-4

CELLULAR COMMUNICATION: LEXUS LINK SYSTEM: 4-4: SERVICES, PHONE or PTT Button Stuck

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.






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 -- Continue to next step.
2. INSPECT ROOF CONSOLE BOX ASSEMBLY (MAYDAY SWITCH ASSEMBLY)




(a) Remove the roof console box assembly.
(b) Measure the resistance of the switch when each switch is pressed.
Standard resistance:





NOTE:
If replacement of the ECU is necessary, replace the mayday battery (backup battery) together with the ECU. After the replacement, register the ECU Programming and Relearning.

NG -- REPLACE ROOF CONSOLE BOX ASSEMBLY
OK -- REPLACE MAYDAY ECU ASSEMBLY