Circuit Description
When you turn the ignition switch to the ON position, the inflatable restraint Sensing and Diagnostic Module (SDM) performs tests in order to diagnose critical malfunctions. Next, the SDM measures IGNITION 1 voltage, the 23-volt loop reserve, and the deployment loop voltages in order to verify the normal ranges. The SDM proceeds with Continuous Monitoring. The SDM contains a network of resistors that is connected to 5 volts, to ground, and to the SDM sensor signal terminal 2. The 8.45K ohm resistor in the inflatable restraint forward discriminating sensor is parallel to the normally open switch, and 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 in order to detect an open sensor or a short to voltage.
Conditions for Setting the DTC
| • | The SDM has an inflatable restraint forward discriminating sensor. |
| • | The voltage at Sensor Feed terminal 2 is more than 4.5 volts for 500 milliseconds. |
The Continuous Monitoring test checks for this DTC. This test occurs if 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 less than 4.5 volts for 500 milliseconds. |
| • | History DTC |
| - | Use a scan tool in order to clear the DTC. |
| - | 250 ignition cycles have occurred without a malfunction. |
Diagnostic Aids
Damaged wiring to the inflatable restraint forward discriminating sensor can cause an intermittent condition. Carefully inspect the sensor input and the ground circuits for broken wires or for 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 in Electrical Diagnosis. 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 correct contact and/or for corrosion of the yellow 2-way connector.
-
This test checks for a malfunction of the inflatable restraint forward discriminating sensor.
-
This test checks for an open in the sensor ground circuit.
-
This test checks for the correct contact and/or for corrosion of the connector of the Sensing and Diagnostic Module (SDM).
-
This test checks for an open in the sensor input circuit.
-
This test checks for a short to voltage in the sensor input circuit.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Was the SIR Diagnostic System Check performed? | -- | ||
Are the terminals damaged or corroded? | -- | |||
3 | Replace the harness connector of the inflatable restraint forward discriminating sensor. Refer to SIR Connector (Plastic Body and Terminal Metal Pin) Repair portion of Wiring Repair . Did you replace the harness connector? | -- | -- | |
4 | Check for the correct connection at terminal 1 and at terminal 2 on the connector of the inflatable restraint forward discriminating sensor. Are the terminals damaged or corroded? | -- | ||
5 | Check for the correct connection at terminal 1 and at terminal 2 on the connector of the inflatable restraint forward discriminating sensor. Are the terminals damaged or corroded? | -- | ||
6 | Replace the inflatable restraint forward discriminating sensor. Refer to Inflatable Restraint Front End Discriminating Sensor Replacement . Has the sensor been replaced? | -- | -- | |
Measure the resistance from terminal 1 to terminal 2 of the inflatable restraint forward discriminating sensor. Is the resistance reading more than the specified value? | 8.54 Kohms | |||
Measure the resistance from terminal 1 of the harness connector of the inflatable restraint forward discriminating sensor to ground. Is the resistance reading within the specified value? | 0-5 ohms | |||
9 | Repair an open condition in the GRY/BLK wire. Is the circuit repair complete? | -- | -- | |
Is the SDM harness connector damaged or corroded? | -- | |||
11 | Replace the SDM harness connector. Refer to SIR Connector (Plastic Body and Terminal Metal Pin) Repair portion of Wiring Repair . Did you replace the SDM harness connector? | -- | -- | |
12 | Check for a correct connection at terminal 2 on the SDM. Is the SDM terminal damaged or corroded? | -- | ||
13 | Check for a correct connection at terminal 2 on the SDM. Is the SDM terminal damaged or corroded? | -- | ||
14 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Did you replace the SDM? | -- | -- | |
Measure the resistance on harness connector terminal 2 of the SDM to terminal 2 of the harness connector of the inflatable restraint forward discriminating sensor. Is the resistance reading within the specified values? | 0-5 ohms | |||
16 | Repair an open condition in the GRY wire. Is the circuit repair complete? | -- | -- | |
Is the measured voltage less than the specified value? | 1 V | |||
18 |
Is the circuit repair complete? | -- | -- | |
19 | Reconnect and mount all the SIR system components. Are all the SIR components reconnected and correctly mounted? | -- | -- | |
20 | Replace the AIR BAG Fuse. Did you replace the AIR BAG Fuse? | -- | -- | |
21 | Reconnect and mount all the SIR system components. Are all the SIR components reconnected and correctly mounted? | -- | -- | |
22 | Clear the SIR diagnostic trouble codes. Did you clear the SIR diagnostic trouble codes? | -- | -- |
