Circuit Description
When you first turn the ignition switch to the ON position, the inflatable restraint Sensing and Diagnostic Module (SDM) performs tests to diagnose critical malfunctions within itself. The SDM then measures IGNITION 1, 23 VLR and the deployment loop voltages to ensure that the deployment loop voltages are within their respective normal voltage ranges. Next, the SDM proceeds to CONTINUOUS MONITORING. The SDM contains a resistor network connected to 5 volts, ground and to the SDM sensor signal terminal 2. The 8.45 K ohm resistor in the inflatable restraint front end discriminating sensor parallel to the normally open switch provides a parallel path to ground. This causes a specified percentage of voltage to appear at the SDM sensor feed input. The SDM monitors this voltage to detect shorts to ground or a closed discriminating sensor.
Conditions for Setting the DTC
| • | The SDM is configured for an inflatable restraint front end discriminating sensor. |
| • | The voltage at sensor feed terminal 2 is less than 0.5 volts for 500 milliseconds. |
The CONTINUOUS MONITORING test checks for this DTC. This test occurs when IGNITION 1 is within the normal operating voltage range.
Action Taken When the DTC Sets
| • | The SDM sets a diagnostic trouble code. |
| • | The SDM turns ON the AIR BAG warning lamp. |
Conditions for Clearing the DTC
| • | Current DTC |
| The voltage at SENSOR FEED terminal 2 is more than 0.5 volts for 500 milliseconds. |
| • | History DTC |
| - | You issue a scan tool CLEAR CODES command. |
| - | 250 ignition cycles occur without a malfunction. |
Diagnostic Aids
A short-to-ground in the inflatable restraint front end discriminating sensor circuit can cause an intermittent condition. Inspect CKT Gr and the inflatable restraint front end discriminating sensor pigtail carefully for cut or chafed wires.
When measurements are requested in this table, use the J 39200 Digital Multimeter with the correct terminal adapter from the J 35616 Connector Test Adapter Kit. When a check for proper connection is requested, refer to Intermittents and Poor Connections . When a wire, connector or terminal repair is requested, use the J-38125 Terminal Repair Kit and refer to Wiring Repair .
Test Description
Caution: Be careful when you handle a sensor. Do not strike or jolt a sensor.
Before applying power to a sensor:
• Remove any dirt, grease, etc. from the mounting surface. • Position the sensor horizontally on the mounting surface. • Point the arrow on the sensor toward the front of the vehicle. • Tighten all of the sensor fasteners and sensor bracket fasteners
to the specified torque value.
The numbers below refer to the step numbers on the diagnostic table.
-
This test checks for a malfunctioning discriminating sensor.
-
This test checks for a short to ground in the GRN wire.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the SIR Diagnostic System Check performed? | -- | ||
Is the resistance reading more than the specified value? | 8.36 Kohms | |||
3 | Replace the inflatable restraint front end discriminating sensor. Refer to Inflatable Restraint Front End Discriminating Sensor Replacement . Did you replace the inflatable restraint front end discriminating sensor? | -- | -- | |
Is the resistance reading less than the specified value? | OL | Go to Integrity Check | ||
5 | Repair a short to ground condition in the GRN wire. Is the circuit repair complete? | -- | -- | |
6 | Reconnect and mount all the SIR system components. Are all the SIR components reconnected and properly mounted? | -- | -- | |
7 | Replace the AIR BAGFuse. Did you replace the AIR BAG Fuse? | -- | -- | |
8 | Reconnect and mount all the SIR system components. Are all the SIR components reconnected and properly mounted? | -- | -- | |
9 | Clear the SIR diagnostic trouble codes. Did you clear the diagnostic trouble codes? | -- | -- |
