Circuit Description
The inflatable restraint Sensing and Diagnostic and Seat Belt Pretensioner Module (SDM) performs tests to diagnose critical malfunctions within itself when the ignition switch is turned ON. The SDM monitors the six firing loops to detect leakage currents to ground and system voltage in the frontal and side air bag inflator module and seat belt pretensioner circuits. The deployment loop resistances are measured to ensure they are within their respective normal resistance ranges. The SDM does the following during one portion of the RESISTANCE MEASUREMENT test:
| • | Measure the voltage difference between the PASSENGER BELT HIGH and the PASSENGER BELT LOW. |
| • | Uses the measured voltage to calculate the resistance of the passenger pretensioner deployment loop. |
Upon passing these tests, and if the energy reserve is charged up, the firing transistors are tested. The SDM then goes into Continuous Monitoring mode. The SDM service wait time is 1 minute. Refer to On-Vehicle Service for enable/disable procedures.
Circuit Description
The inflatable restraint Sensing and Diagnostic and Seat Belt Pretensioner Module (SDM) performs tests to diagnose critical malfunctions within itself when the ignition switch is turned ON. The SDM monitors the firing loops to detect leakage currents to ground and system voltage in the air bag inflator module and seat belt pretensioner circuits. The deployment loop resistances are measured to ensure they are within their respective normal resistance ranges. The SDM service wait time is 1 minute. Refer to On-Vehicle Service for enable/disable procedures
Conditions for Setting the DTC
The passenger seat belt pretensioner deployment loop resistance is more than 4.4 ohms. The passenger seat belt side buckle pretensioner deployment loop consists of the following components:
| • | The passenger seat belt side buckle pretensioner. |
| • | The harness wiring of CKT AB900 and CKT AB950. |
| • | The harness wiring of CKT XB901 and CKT XB950. |
| • | The connector terminal contact. |
The RESISTANCE MEASUREMENT test checks for this malfunction. This test only occurs continuously during each ignition cycle when the IGNITION 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 and History DTC codes must be cleared using a scan tool Clear DTC Information command. If the circuit fault has been successfully repaired and the conditions which caused the DTC to set are no longer existing, the DTC may be cleared using the scan tool. If the resistance in the passenger seat belt side buckle pretensioner circuit is less than 4.4 ohms, a Current DTC 37 will change to a History DTC 37, which may be cleared using the scan tool.
Diagnostic Aids
A poor connection can cause an intermittent condition. Check the following for a poor connection:
| • | The 8-way passenger seat connector C316A terminals 1 and 2. |
| • | The SDM terminals 15 and 45. |
| • | The wire to terminal connections in CKT AB900 and CKT AB950. |
| • | The wire to terminal connections in CKT XB901 and CKT XB950. |
| • | The passenger seat belt side buckle pretensioner integral 2-way connector. |
Inspect CKTs AB900, XB901, AB950 and XB950 carefully for cutting and/or chafing. The diagnostic table directs the technician to note the entry value of the RH PRETENS RESIST. Comparing the value of the RH PRETENS RESIST. over multiple ignition cycles can be helpful in determining if an intermittent condition exists.
When measurements are requested in this table, use J 39200 Digital Multimeter with the correct terminal adapter from 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 J-38125 Terminal Repair Kit and refer to Wiring Repair .
Test Description
The numbers below refer to step numbers on the diagnostic table.
-
This test determines whether the malfunction is in CKT AB900 or AB950 between the SDM harness connector and C316.
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This test determines whether the malfunction is in CKT XB901 or XB950 between the SDM harness connector and C316.
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This test determines whether the malfunction is in the passenger pretensioner belt assembly. This is done by substituting the known good resistance of the load tool and then observing if the malfunction is still present.
-
This test determines if the malfunction is in CKT AB900 in the passenger pretensioner seat harness.
-
This test determines if the malfunction is in CKT XB901 in the passenger pretensioner seat harness.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the SIR Diagnostic System Check performed? | -- | ||
2 |
Has RH PRETENS RESIST. been read and recorded on the repair order? | -- | -- | |
3 |
Are the terminals damaged and/or corroded? | -- | ||
4 | Repair the 8-way body harness-to-passenger seat connector C316. Refer to SIR Connector (Plastic Body and Terminal Metal Pin) Repair in this section. Is the repair complete? | -- | -- | |
5 | Check for proper connection at terminals 1 and 2 on C316A on the 8-way passenger seat connector. Are the terminals damaged and/or corroded? | -- | ||
6 | Repair C316A on the 8-way passenger seat connector. Is the repair complete? | -- | -- | |
7 |
Are the terminals damaged and/or corroded? | -- | ||
8 | Use the J 42250 Catera Terminal Repair Kit to repair the SDM harness connector. Are the repairs complete? | -- | -- | |
9 | Check for proper connection at terminals 15 and 45 on the SDM. Are the terminals damaged and/or corroded? | -- | ||
10 | Check for proper connection at terminals 15 and 45 on the SDM. Are the terminals damaged and/or corroded? | -- | ||
11 | Replace the inflatable restraint Sensing and Diagnostic and Seat Belt Pretensioner Module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic and Seat Belt Pretensioner Module Replacement . Is the replacement complete? | -- | -- | |
Use the J 39200 Digital Multimeter to measure the resistance on the SDM harness connector terminal 45 and the body harness-to-passenger seat connector C316 terminal 1. Is the resistance reading within the specified values? | 0-0.5 ohms | |||
13 | Repair the high resistance in CKT AB900 or AB950 between the 8-way body harness-to-passenger seat connector C316 and the SDM harness connector. Is the repair complete? | -- | -- | |
Measure the resistance between the SDM harness connector terminal 15 and the body harness-to-passenger seat connector C316 terminal 2. Is the resistance reading within the specified values? | 0-0.5 ohms | |||
15 | Repair the high resistance in CKT XB901 or XB950 between the 8-way body harness-to-passenger seat connector C316 and the SDM harness connector. Is the repair complete? | -- | -- | |
Is RH PRETENS RESIST. greater than the specified value? | 4.4 ohms | |||
17 |
Is the replacement complete? | -- | -- | |
Is the resistance reading within than the specified values? | 0-0.5 ohms | |||
19 | Repair the high resistance in CKT AB900 between the passenger pretensioner yellow 2-way integral harness connector terminal 1 and the 8-way passenger seat connector C316A terminal 1. Is the repair complete? | -- | -- | |
Use the J 39200 Digital Multimeter to measure the resistance between the passenger pretensioner yellow 2-way integral harness connector terminal 2 and the passenger seat connector C316A terminal 2. Is the resistance reading within the specified values? | 0-0.5 ohms | Go to Integrity Check | ||
21 | Repair the high resistance in CKT XB901 between the passenger pretensioner yellow 2-way integral harness connector terminal 2 and the 8-way passenger seat connector C316A terminal 2. Is the repair complete? | -- | -- | |
22 | Reconnect all the SIR system components. Ensure all the components are properly mounted. Are all the SIR system components reconnected and are all the SIR system components properly mounted? | -- | -- | |
23 | Clear the SIR diagnostic trouble codes. Are the SIR diagnostic trouble codes cleared? | -- | -- |
