Sable V6-3.0L VIN U (1999)
Air Bag Diagnostic Module: Description and Operation
The air bag Electronic Crash Sensor (ECS) module:
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discriminates between an event that warrants frontal air bag deployment and an event that does not.
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signals the inflators to deploy the air bags in the event of a deployable crash.
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monitors the air bag Supplemental Restraint System (SRS) for faults.
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illuminates the air bag indicator if a fault is detected.
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flashes the air bag indicator to indicate the Lamp Fault Code (LFC) detected.
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communicates through the Data Link Connector (DLC) the current and historical Diagnostic Trouble Codes (DTCs).
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activates a chime in the Generic Electronic Module (GEM) if the air bag indicator is not available and another SRS system fault exists.
AIR BAG SYSTEM FUNCTIONS
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The air bag Electronic Crash Sensor (ECS) module illuminates the AIR BAG indicator for approximately six seconds when the ignition switch is
turned to RUN 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 ECS.
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Lamp Fault Codes (LFCs), if present, will begin flashing approximately 30 seconds after the ignition switch has been turned to RUN. This is the
amount of time it takes the ECS to perform all tests and verify system faults, if present.
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LFCs are displayed as a series of flashes and pauses of the AIR BAG indicator. LFCs are two-digit numbers.
Example: An LFC 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)...
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LFCs are prioritized numerically so that if two or more faults occur at the same time, the LFC with the highest priority will be displayed.
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After the LFC is displayed five times, the air bag indicator will illuminate continuously until the ignition switch is cycled.
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The ECS incorporates Non-Volatile Random Access Memory (NVRAM) to store Diagnostic Trouble Codes (DTCs) and retain them for 254 key
cycles. The ECS will always display the highest priority DTC stored in NVRAM. DTCs may be cleared from the ECS after the fault conditions are
serviced.
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If a system fault exists and the air bag warning indicator is not functioning, an audible chime will be heard indicating a need for service. The chime
is a series of five sets of five beeps. This does not indicate an LFC 55 or any other DTC. The air bag warning indicator must be serviced before
LFCs can be determined.
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The ECS includes an internal back-up power supply. This feature provides sufficient back-up power to deploy the air bags in the event that the
