When you first turn the ignition switch to the RUN position, the inflatable restraint sensing and diagnostic module (SDM) performs tests in order to diagnose critical malfunctions within itself. Then the SDM measures Ignition Positive Voltage, 23 VLR and the deployment loop voltages in order to ensure they are within the normal voltage ranges. Then the SDM proceeds to Continuous Monitoring. The SDM contains a resistor network connected to 5 volts, ground, and to the SDM front end sensor signal terminal 9. The 1 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 front end sensor signal input. The SDM monitors this voltage in order to detect shorts to power or an open discriminating sensor.
• | The SDM is configured for an inflatable restraint front end discriminating sensor |
• | The voltage at front end sensor signal terminal 9 is more than 5.0 volts for 500 milliseconds. |
The Continuous Monitoring test checks for this DTC. This test occurs when Ignition Positive Voltage is within the normal operating voltage range.
• | The SDM sets a Diagnostic Trouble Code. |
• | The SDM turns ON the AIR BAG warning lamp. |
• | Current DTC |
The voltage at front end sensor signal terminal 9 is less than 3.2 volts for 500 milliseconds. |
• | History DTC |
- | You issue a scan tool Clear DTCs command. |
- | 250 ignition cycles have passed since the last malfunction. |
A broken or chafed wire in the inflatable restraint front end discriminating sensor circuit may cause an intermittent condition. Carefully inspect CKT 1834 (YEL) and CKT 1751 (BLK/WHT) 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 an inspection for proper connection is requested, refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. When a wire, connector or terminal repair is requested, use the J-38125 Terminal Repair Kit. Refer to Wiring Repairs in Wiring Systems.
The numbers below refer to the step numbers on the diagnostic table:
This test checks for proper contact or corrosion of the yellow 2-way connector.
This test checks for a malfunctioning discriminating sensor.
This test checks for an open in CKT 1751 (BLK/WHT).
This test checks for proper contact or corrosion of the inflatable restraint sensing and diagnostic module (SDM) connector.
This test checks for an open in CKT 1834 (YEL).
This test checks for a short to voltage in CKT 1834 (YEL) .
Step | Action | Value(s) | Yes | No |
---|---|---|---|---|
1 | Was the SIR Diagnostic System Check performed? | -- | Go to Step 2 | |
Are the terminals damaged or corroded? | -- | Go to Step 3 | Go to Step 5 | |
3 | Replace the sensor harness connector. Refer to Wiring Repairs in Wiring Systems. Are the repairs complete? | -- | Go to Step 4 | -- |
4 | Check for proper connection at the sensor connector terminals A and B. Are the terminals damaged or corroded? | -- | Go to Step 6 | Go to Step 19 |
5 | Check for proper connection at the sensor connector terminals A and B. Are the terminals damaged or corroded? | -- | Go to Step 6 | Go to Step 7 |
6 | Replace the inflatable restraint front end discriminating sensor. Refer to Inflatable Restraint Front End Discriminating Sensor Replacement . Has the inflatable restraint front end discriminating sensor been replaced? | -- | Go to Step 19 | -- |
Measure the resistance between the sensor connector terminals A and B. Is the resistance reading more than the specified value? | 1050 ohms | Go to Step 6 | Go to Step 8 | |
Measure the resistance from the sensor harness connector terminal B to ground. Is the resistance less than the specified value? | 5 ohms | Go to Step 10 | Go to Step 9 | |
9 | Repair an open condition in CKT 1751 (BLK/WHT). Refer to Wiring Repairs in Wiring Systems. Are the repairs complete? | -- | Go to Step 19 | -- |
Is the connector damaged or corroded? | -- | Go to Step 11 | Go to Step 13 | |
11 | Replace the SDM harness connector. Refer to Wiring Repairs in Wiring Systems. Are the repairs complete? | -- | Go to Step 12 | -- |
12 | Check for proper connection at terminal 9 of the SDM. Is the terminal damaged or corroded? | -- | Go to Step 14 | Go to Step 19 |
13 | Check for proper connection at terminal 9 of the SDM. Is the terminal damaged or corroded? | -- | Go to Step 14 | Go to Step 15 |
14 | Replace the inflatable restraint sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Has the SDM been replaced? | -- | Go to Step 19 | -- |
Measure the resistance between the sensor harness connector terminal A and the SDM harness connector terminal 9. Is the resistance less than the specified value? | 5 ohms | Go to Step 17 | Go to Step 16 | |
16 | Repair an open condition in CKT 1834 (YEL). Refer to Wiring Repairs in Wiring Systems. Are the repairs complete? | -- | Go to Step 19 | -- |
Is the measured voltage less than the specified value? | 1 V | Go to Step 18 | ||
18 |
Are the repairs complete? | -- | Go to Step 19 | -- |
19 | Reconnect all the SIR system components, make sure all the components are properly mounted. Have all the SIR components been reconnected and properly mounted? | -- | Go to Step 20 | -- |
20 | Clear all the SIR DTCs. Have all the SIR DTCs been cleared? | -- | -- |