DTC 098

Schematic:

CIRCUIT DESCRIPTION
When you first turn ON the ignition, the inflatable restraint sensing and diagnostic and Seat Belt Pretensioner Module (SDM) performs tests to diagnose critical malfunctions within itself. Then, the SDM proceeds with the RESISTANCE MEASUREMENT test to measure the deployment loop resistances to ensure that they are within their respective normal resistance ranges. Upon passing these tests, the energy reserve is charged and the firing transistors are tested. The SDM then goes into the CONTINUOUS MONITORING mode. The SDM is hardwired to the Body Control Module (BCM) through the Deployment Commanded Output (DCO) circuit. During the CONTINUOUS MONITORING mode, the SDM sends fixed frequency pulses to the BCM. In the event of a collision involving air bag or seat belt pretensioner deployment, the SDM sends higher frequency pulses to the BCM, which in turn sends a Class 2 message to the ONSTAR module. Upon receiving the Class 2 message, the ONSTAR module transmits a deployment commanded output (DCO) signal to the service center via the vehicle's cellular telephone.

CONDITIONS FOR RUNNING THE DTC
When the ignition voltage is within the normal operating voltage range and the SDM is in the CONTINUOUS MONITORING mode, the SDM monitors the DCO circuit in order to detect leakage currents to ground in the DCO circuit.

CONDITIONS FOR SETTING THE DTC
The measured leakage current to ground is above a specified value in the DCO circuit.

ACTION TAKEN WHEN THE DTC SETS
The SDM turns ON the AIR BAG warning lamp.

CONDITIONS FOR CLEARING THE DTC
You can issue a CLEAR CODES command. A history DTC will clear once 255 malfunction free ignition cycles have occurred.

DIAGNOSTIC AIDS
A short to ground in the DCO circuit can cause an intermittent condition. Inspect the DCO circuit carefully for cutting and/or chafing.

TEST DESCRIPTION

Steps 1 - 10:

Steps 11 - 15:

2. This step checks the SDM wiring harness connector.
4. This step checks the SDM terminals.
6. This step checks the BCM wiring harness connector C1.
8. This step checks the BCM terminals.
10. This step checks for a short to ground in the DCO circuit.
12. This step determines if there is a malfunctioning BCM or if there is a malfunctioning SDM.