Circuit Description
The driver frontal air bag deployment loop is a 2 wire circuit. One wire is the high side of the loop while the other is the low side of the loop. When you first turn the ignition switch ON, the supplemental restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. Then the SDM performs the following continuous diagnostic tests on the deployment loops:
| • | Deployment loop voltage out of range test |
| • | Deployment loop resistance measurement test |
If the voltage out of range test detects a short to voltage condition, the resistance measurement test for that deployment loop will not be performed.
Conditions for Running the DTC
The SDM monitors the driver frontal air bag deployment loop at power on and continuously there after.
Conditions for Setting the DTC
| • | Deployment loop voltage out of range test. |
| - | Ignition 1 voltage is within the normal operating voltage range. |
| - | Driver frontal high terminal is less than 2.4 volts and driver frontal deployment loop resistance is greater than or equal to 6 ohms for 5 consecutive samples, the SDM sets this code. |
| • | Deployment loop resistance measurements test. |
| - | Ignition 1 voltage is within the normal operating voltage range. |
| - | Driver frontal deployment loop resistance is greater than 4.8 ohms for 5 consecutive samples, the SDM sets this code. |
The driver frontal deployment loop consists of the following components:
| • | Supplemental restraint steering wheel inflator module. |
| • | Supplemental restraint steering wheel module coil. |
| • | Harness wiring of driver frontal high and low deployment circuits. |
| • | Connector terminal contact. |
Action Taken When the DTC Sets
| • | The SDM sets a DTC. |
| • | The SDM commands AIR BAG warning lamp ON through a Class 2 message to the cluster (IP). |
The SDM also sets this DTC as current after an accident. The SDM will write the status of this DTC to the "crash log" area of the EEPROM for retrieval.
Conditions for Clearing the DTC
| • | Current DTC |
| - | Driver frontal high terminal is less than 2.4 volts and driver frontal deployment loop resistance is less than 6 ohms for 5 consecutive samples. |
| - | Driver frontal high deployment loop resistance is less than or equal to 4.8 ohms for 5 consecutive samples. |
| - | CLEAR CODES command. |
| • | History DTC |
| - | You issue a scan tool CLEAR CODES command. |
| - | Once 255 malfunctions free ignition cycles have occurred. |
Diagnostic Aids
If the DTC is a stored as a history DTC the deployment circuit must be checked for:
| • | Frayed insulation |
| • | Damaged connectors |
| • | Moisture damage |
| • | Stretched/broken wires |
The fact that the DTC set and now is stored as a history DTC indicates an open or high resistance between the two sides of the deployment circuit has happened in the past. The open or high resistance will prevent deployment if it happens again during a commanded air bag deployment.
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
-
This step checks the driver inflator module in-line connector below the supplemental restraint steering wheel module coil.
-
This step test for the proper operation of supplemental restraint steering wheel module coil and/or supplemental restraint steering wheel inflator module.
-
This step checks to see if the supplemental restraint sensing and diagnostic module (SDM) wiring harness connector is OK.
-
This step checks to see if there is an open or a high resistance in the driver frontal high circuit.
-
This step determines if there is an open or a high resistance in the driver frontal low circuit, or if there is a malfunctioning SDM.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the A Diagnostic System Check - SRS? | -- | ||||||||
Does connector exhibits any signs of corrosion, terminal damaged, or poor connections? | -- | |||||||||
3 |
Did you complete the replacement? | -- | -- | |||||||
4 |
Does the scan tool indicate that this DTC is current? | -- | Go to Diagnostic Aids | |||||||
5 |
Does the scan tool indicate that this DTC is current? | -- | ||||||||
Does the scan tool indicate that this DTC is current? | -- | |||||||||
7 |
Did you complete the replacement? | -- | -- | |||||||
8 |
Did you complete the replacement? | -- | -- | |||||||
Is the SDM wiring harness connector OK? | -- | |||||||||
10 | Replace the SDM wiring harness connector. Refer to Connector Repairs in Wiring Systems. Did you complete the replacement? | -- | -- | |||||||
Use the DMM and measure the resistance between driver frontal high deployment circuit of in-line connector and the SDM wiring harness connector. Does the resistance measure less than the specified value? | 0-0.5 ohms | |||||||||
12 | Locate and repair an open or a high resistance in the driver frontal high circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||
Use the DMM and measure the resistance between driver frontal low deployment circuit of in-line connector and the SDM wiring harness connector. Does the resistance measure less than the specified value? | 0-0.5 ohms | |||||||||
14 | Locate and repair an open or a high resistance in the driver frontal low circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||
15 | Replace the SDM. Refer to Supplemental Restraint Sensing and Diagnostic Module Replacement . Did you complete the replacement? | -- | -- | |||||||
16 |
Did you complete the action? | -- | -- |
