B0024

DTC B0024 LF/Driver Frontal Deployment Loop (Single Stage or Stage 1) Short to Ground/Voltage Out of Range

Schematic:

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 inflatable 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
^ If the SDM detects the driver frontal high is greater than 6 volts for 5 consecutive samples, the SDM sets this DTC.
^ Driver frontal high terminal is less than 2.4 Volts and driver frontal deployment loop resistance is less than 6 Ohm for 5 consecutive samples, the SDM sets this DTC.

The driver frontal deployment loop consists of the following components:
^ Inflatable restraint steering wheel module.
^ Inflatable 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).

CONDITIONS FOR CLEARING THE DTC
^ Current DTC
- Driver frontal high is less than or equal to 6 Volts for 5 consecutive samples.
- Driver frontal high terminal is greater than or equal to 2.4 Volts and driver frontal deployment loop resistance is less than 6 Ohm 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 a short to ground or to voltage on either of the two sides of the deployment circuit has happened in the past. The short to ground or voltage will prevent deployment if it happens again during a commanded air bag deployment.

TEST DESCRIPTION

Test Step 1 - Step 5:

Test Step 6 - Step 13:

Test Step 14 - Step 18:

The number(s) below refer to the step number(s) on the diagnostic table.
2. This step checks the driver inflator module in-line connector below the steering wheel restraint module coil.
6. This step test for the proper operation of inflatable restraint steering wheel module coil and/or inflatable restraint steering wheel inflator module.
9. This step checks to see if there is a short to ground in the driver frontal high deployment circuit.
11. This step checks to see if there is a short to ground in the driver frontal low deployment circuit.
13. This step checks to see it there is a short to voltage in the driver frontal high deployment circuit.
15. This step determines if there is a short to voltage in the driver frontal low deployment circuit, or if there is a malfunctioning SDM.
18. This step clears all SIR DTC's.