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. Next, the SDM measures IGNITION 1, 23 VLR and the deployment loop voltages to ensure that they are within their respective normal voltage ranges. The SDM then proceeds to CONTINUOUS MONITORING. The SDM contains a resistor network connected to 5 volts, ground and to the SDM sensor signal terminal 2. The 8.45K 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 power or an open 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 more than 4.5 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 less than 4.5 volts for 500 milliseconds. |
| • | History DTC |
| - | You issue a scan tool CLEAR CODES command. |
| - | 250 ignition cycles have occurred without a malfunction. |
Diagnostic Aids
A broken or chafed wire in the inflatable restraint front end discriminating sensor circuit can cause an intermittent condition. Inspect CKT Gr and CKT Gr/B 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 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 proper contact and/or corrosion of the yellow 2-way connector.
-
This test checks for a malfunctioning discriminating sensor.
-
This test checks for an open in CKT Gr/B.
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This test checks for proper contact and/or corrosion of the inflatable restraint Sensing and Diagnostic Module (SDM) connector.
-
This test checks for an open in CKT Gr.
-
This test checks for a short to voltage in CKT Gr.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the SIR Diagnostic System Check performed? | -- | ||
Are the terminals damaged or corroded? | -- | |||
3 | Replace the inflatable restraint front end discriminating sensor harness connector. Refer to SIR Connector (Plastic Body and Terminal Metal Pin) Repair portion of Wiring Repair . Did you replace the inflatable restraint front end discriminating sensor harness connector? | -- | -- | |
4 | Check for proper connection at terminal A1 and terminal A2 on the inflatable restraint front end discriminating sensor connector. Are the terminals damaged or corroded? | -- | ||
5 | Check for proper connection at terminal A1 and terminal A2 on the inflatable restraint front end discriminating sensor connector. Are the terminals damaged or corroded? | -- | ||
6 | Replace the inflatable restraint front end front end discriminating sensor. Refer to Inflatable Restraint Front End Discriminating Sensor Replacement . Has the front end discriminating sensor been replaced? | -- | -- | |
Measure the resistance of the inflatable restraint front end discriminating sensor from terminal A1 to terminal A2. Is the resistance reading more than the specified value? | 8.54 Kohms | |||
Measure the resistance from the inflatable restraint front end discriminating sensor harness connector terminal A2 to ground. Is the resistance reading within the specified value? | 0-5ohms | |||
9 | Repair an open condition in the GRN/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 proper connection at terminal 2 on the SDM. Is the SDM terminal damaged or corroded? | -- | ||
13 | Check for a proper 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 the SDM harness connector terminal 2 to the inflatable restraint front end discriminating sensor harness connector terminal A1. Is the resistance reading within the specified values? | 0-5ohms | |||
16 | Repair an open condition in the GRN wire. Is the circuit repair complete? | -- | -- | |
Is the measured voltage less than the specified value? | 1 V | Go to Integrity Check | ||
18 |
Is the circuit repair complete? | -- | -- | |
19 | Reconnect and mount all the SIR system components. Are all the SIR components reconnected and properly 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 properly mounted? | -- | -- | |
22 | Clear the SIR diagnostic trouble codes. Did you clear the SIR diagnostic trouble codes been cleared? | -- | -- |
