After replacing the dimmer switch on my 1997 Expedition I am getting the air bag light on the dash. It flashes 5 times then 2 times and then stays on solid. Help!!!

 

is it a 52 or 42?

here are the 2 most common.


CODE 52

LFC 24/DTC B1342, B1924 — System Disarm Fault or Air Bag Diagnostic Monitor is Faulted

Normal Operation

When the air bag diagnostic monitor detects a diagnostic trouble code (DTC) B1913 or B1914 fault, it attempts to disarm the air bag supplemental restraint system (SRS) by activating an internal solid state switch at Pin C209-13, Circuit 937 (R/W).

The activation of this switch shorts Circuit 937 (R/W) to ground, causing the power distribution box Fuse 2 (10 A) to open, disarming the SRS and preventing inadvertent air bag deployment.

WARNING: Do not under any circumstances substitute another fuse value for the power distribution box fuse 2 (10 a). Any fuse other than 10 a can cause disarming fault and can result in danger to the occupants of the vehicle. Do not attempt to replace the power distribution box fuse 2 (10 a) unless the battery ground cable has been disconnected and the backup power supply energy has been depleted. To deplete the backup power supply energy, disconnect the battery ground cable and wait one minute. Be sure to disconnect auxiliary batteries and power supplies (if so equipped).

The air bag diagnostic monitor will make up to three attempts spaced at one minute apart to open the fuse. If the attempt to open the fuse is successful, a DTC B1867 will be stored in memory. If the attempts to open the fuse are unsuccessful, a DTC B1924 will be stored in memory. After the power distribution box Fuse 2 (10 A) has been opened or three attempts to open it have failed, the air bag diagnostic monitor will not attempt to disarm the SRS again until DTC B1924 or B1913 has been repaired and cleared from memory.

The air bag diagnostic monitor also performs several self-tests every time the ignition switch is turned to the RUN position. If any of these tests fail, the air bag diagnostic monitor will flash a lamp fault code (LFC) 24. If any of these conditions later resumes normal operation, the DTC B1924 will be stored in memory.

The fault will either generate a DTC B1924 or B1342, depending on the cause of the fault. DTC B1342 is a special case DTC that will only be retrieved as a result of running the On-Demand Self Test. An intermittent B1342 cannot exist due to this fact. This DTC indicates that an internal microprocessor fault exists in the air bag diagnostic monitor. DTC B1924 covers the other internal air bag diagnostic monitor faults and is handled like any other DTC.

Possible Causes

WARNING: Do not under any circumstances substitute another fuse value for the power distribution box fuse 2 (10 a). Any fuse other than 10 a can cause disarming fault and can result in danger to the occupants of the vehicle. Do not attempt to replace the power distribution box fuse 2 (10 a) unless the battery ground cable has been disconnected and the backup power supply energy has been depleted. To deplete the backup power supply energy, disconnect the battery ground cable and wait one minute. Be sure to disconnect auxiliary batteries and power supplies (if so equipped).

System disarm fault or internal diagnostic fault can be caused by:

an improper fuse value in the power distribution box fuse slot 2.
excessive resistance or opens in the battery feed circuit due to corrosion, poor crimps, etc. The excess resistance could occur in the wiring at the air bag diagnostic monitor harness Pin C209-13, the 10 A power distribution box Fuse 2 terminal, or elsewhere in the battery feed circuit.
a vehicle charging system concern preventing the air bag diagnostic monitor from drawing enough current to perform its disarm.
an air bag diagnostic monitor fault of on-board diagnostic or system disarm.
resistance to ground in the normally open air bag sensor feed Circuits 617 (PK/O), 619 (PK/W), 624 (Y/W), and 625 (Y/LG).


CODE 42

You could also be mistaking a code 42 for a code 24

LFC 42/DTC B1942 — LH Air Bag Sensor Feed/Return Circuit Open

Normal Operation

The voltage at Pin C209-15, Circuit 619 (PK/W), is set by the air bag diagnostic monitor to be slightly less than battery voltage. Circuit 619 (PK/W) is connected to Circuit 625 (Y/LG) inside the LH air bag sensor. Therefore, the voltage at Pin C208-23, Circuit 625 (Y/LG) should be the same as the voltage at Pin C209-15, Circuit 619 (PK/W).

The air bag diagnostic monitor periodically pulls the voltage at Pin C209-15, Circuit 619 (PK/W), low to verify the connection to Pin C208-23, Circuit 625 (Y/LG). If the voltage at Pin C208-23, Circuit 625 (Y/LG), does not pull low as a result of this test, the air bag diagnostic monitor will store in memory the diagnostic trouble code (DTC) B1942 and flash a lamp fault code (LFC) 42 on the air bag indicator. If the connection between Pin C209-15, Circuit 625 (Y/LG), and Pin C208-23, Circuit 625 (Y/LG), is later repaired, the DTC B1942 will be stored in memory.

Possible Causes

Failure to get low voltage at Pin C208-23, Circuit 625 (Y/LG), during the test can be caused by:

an open circuit in the wiring harness in either Circuit 619 (PK/W) or Circuit 625 (Y/LG).
an open circuit inside the LH air bag sensor across Circuit 619 (PK/W) or Circuit 625 (Y/LG).
a short to battery or ignition voltage in any of the Circuits 617 (PK/O), 619 (PK/W), 624 (Y/W), or 625 (Y/LG).

 

LFC 52 can be cleared with the correct scanner. Otherwise, it will clear after 256 error-free ignition cycles.