Retrieving Lamp Flash Codes (LFC)

PURPOSE
Performing system diagnostics is the main purpose of the air bag diagnostic monitor.

The air bag diagnostic monitor continually monitors all air bag system components and wiring connections for possible faults when the ignition switch is in RUN position.

OPERATION
It does not deploy the air bags in the event of a collision. The air bag diagnostic monitor operates in the following manner:

- If the air bag diagnostic monitor detects a fault in the air bag system, a Diagnostic Trouble Code (DTC) will be written to the air bag diagnostic monitor's Non-Volatile Random Access Memory (NVRAM).

- This DTC will then be displayed on the air bag indicator lamp.

- After servicing, the DTC may then be cleared from NVRAM.

- The air bag diagnostic monitor illuminates the air bag indicator for approximately six seconds when the ignition switch is turned to the RUN position and then turns the air bag indicator Off. This indicates that the air bag indicator is operational. If the air bag indicator does not illuminate at all, stays On continuously, or flashes at any time, then a fault has been detected by the air bag diagnostic monitor.

- Diagnostic trouble codes, if present, will begin flashing within 30 seconds after the ignition switch has been turned to the RUN position. This is the amount of time it takes the air bag diagnostic monitor to perform all tests and verify system faults, if present.

- DTCs are displayed as a series of flashes and pauses of the air bag indicator. DTCs are two-digit numbers. Example: A DTC 32 is displayed as follows:

flash flash flash - (two second pause) - flash flash - (five second pause)...

flash flash flash - (two second pause) - flash flash - (five second pause)...

- DTCs are prioritized numerically so that if two or more faults occur at the same time, the diagnostic trouble code with the highest priority will be displayed.

- After the DTC is displayed five times, the air bag indicator will illuminate continuously until the ignition switch is cycled.
- The air bag diagnostic monitor incorporates NVRAM to store DTCs and retain them indefinitely. The air bag diagnostic monitor will always flash the highest priority DTC stored in NVRAM. DTCs may be cleared from the air bag diagnostic monitor after the fault conditions are serviced.

- The air bag diagnostic monitor distinguishes between hard and intermittent (or repaired) fault conditions.

+ Each DTC number 12-45 represents a hard fault (a fault that is still present). Hard diagnostic trouble codes are higher priority than intermittent diagnostic trouble codes, and may not be cleared from NVRAM.

+ Each of these hard DTCs has an equivalent DTC which is the sum of the DTC number plus 40. This equivalent DTC will indicate that an intermittent condition exists, or that a hard condition has been repaired.

+ Only the intermittent (repaired) DTCs, numbers 52-85, may be cleared from the air bag diagnostic monitor. Example: A DTC 32 indicates that high resistance in the driver side air bag circuit has been, and still is, present. A DTC 72 (32 + 40) indicates that high resistance in the driver side air bag circuit existed at one time, but no longer exists due to an intermittent condition, or a repair made to the circuit.

- If a system fault exists and the air bag warning indicator is not functioning, an audible tone will be heard indicating a need for service. The tone is a series of five sets of five beeps. This does not indicate a DTC 55 or any other DTC. The air bag warning indicator must be serviced before DTC can be determined.