Malfunction Lamp / Indicator: Description and Operation

AIR BAG WARNING LAMP




The instrument cluster contains an air bag warning indicator and sensing and diagnostic module (SDM). The SDM performs a turn-on test when the ignition is turned ON.

The SDM flashes the air bag indicator seven times by supplying an intermittent ground to the indicator lamp circuit. After flashing seven times, the air bag indicator will turn off if no more malfunctions have been detected.

If the SDM has detected malfunctions in the internal and external circuits, which could potentially affect the operation of the supplemental inflatable restraints (SIR), the air bag indicator stays on. Some malfunctions could result in non-deployment when necessary or deployment under conditions which would not normally result in deployment.

When the SDM is not properly attached to its connector, the air bag circuit is shorted to ground because there is a shorting bar in the SDM electrical connector. The shorting bar is disengaged when proper connection is made, but if a poor connection exists the SDM connector supplied a ground to the air bag indicator independently of the SDM, and the air bag indicator turns on.