For 1990-2009 cars
SIR Components
SIR Schematics
Handling ESD Sensitive Parts Notice
SIR Caution
SIR Caution
Handling ESD Sensitive Parts Notice

### 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 DRIVER 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.

### Conditions for Setting the DTC

The passenger seat belt side buckle pretensioner deployment loop resistance is less than 1.0 ohms. The passenger seat belt side buckle pretensioner deployment loop consists of the following components:

• | Passenger seat belt side buckle pretensioner.

• | Harness wiring of CKT AB900 and CKT AB950.

• | Harness wiring of CKT XB901 and CKT XB950.

• | Connector terminal contacts, including shorting bars.

The deployment loop resistance test checks for this malfunction.

### 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 Current DTC 38 to set are no longer existing, History DTC 38 will set. History DTC 38 may be cleared using the scan tool.

### Diagnostic Aids

Inspect CKTs AB900, AB950, XB901 and XB950 carefully for cutting and/or chafing. The diagnostic table directs the technician to note the value of RH PRETENS RESIST. Comparing the value of 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.

1. This test determines the deployment loop resistance measured by the inflatable restraint sensing and diagnostic module.

2. This test checks for proper contact or corrosion of the SDM connector.

3. This test checks for a short from CKT AB900 or AB950 to CKT XB901 or XB950.

4. This test checks for a short in the driver pretensioner seat harness.

5. This test determines whether the malfunction is in the driver 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.

#### DTC 38 Passenger Pretensioner Deployment Loop Resistance Too Low

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the SIR Diagnostic System Check performed? | -- | Go to Step 2 | Go to SIR Diagnostic System Check
2 |

1. Turn the ignition switch to the OFF position.
2. Connect a scan tool to the data link connector. Follow the directions in the scan tool instruction manual.
3. Turn the ignition switch to the ON position.
4. Request the SIR data list display.
5. Read and record on the repair order the passenger pretensioner deployment loop resistance RH PRETENS RESIST.

Has the RH PRETENS RESIST. been read and recorded on the repair order?

--

Go to Step 3

--

3 |

1. Turn the ignition switch to the OFF position.
2. Wait one minute until the SDM energy reserve capacitors have discharged.
3. Disconnect the negative battery cable. Refer to

   Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

   .
4. Disconnect the 8-way body harness-to-passenger seat connector C316 from the 8-way passenger seat connector located under the RH front seat track cover.
5. Check for proper connection at terminals 1 and 2 on the 8-way body harness-to-passenger seat connector C316.

Are the terminals damaged or corroded?

--

Go to Step 4

Go to Step 6

4 | Repair the 8-way body harness-to-passenger seat connector C316. Refer to Wiring Repair . Is the repair complete? | -- | Go to Step 5 | --
5 | Check for proper connection at terminals 1 and 2 on C316A on the 8-way passenger seat connector. Are the terminals damaged or corroded? | -- | Go to Step 7 | Go to Step 19
6 | Check for proper connection at terminals 1 and 2 on C316A on the 8-way passenger seat connector. Are the terminals damaged or corroded? | -- | Go to Step 7 | Go to Step 8
7 | Repair the 8-way body harness-to-passenger seat connector C316. Refer to Wiring Repair . Is the repair complete? | -- | Go to Step 19 | --
8 |

1. Disconnect 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 .
2. Check for proper connection at terminals 15 and 45 of the SDM harness connector.

Are the terminals damaged or corroded?

--

Go to Step 9

Go to Step 11

9 | Use the J 42250 Catera Terminal Repair Kit to repair the SDM harness connector. Are the repairs complete? | -- | Go to Step 10 | --
10 | Check for proper connection at terminals 15 and 45 on the SDM. Are the terminals damaged or corroded? | -- | Go to Step 12 | Go to Step 18
11 | Check for proper connection at terminals 15 and 45 on the SDM. Are the terminals damaged or corroded? | -- | Go to Step 12 | Go to Step 13
12 | 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? | -- | Go to Step 19 | --
13 |

1. Zero the J 39200 Digital Multimeter.
2. Use the J 39200 Digital Multimeter to measure the resistance between the SDM harness connector terminals 15 and 45.

Is the resistance reading less than the specified value?

OL

Go to Step 14

Go to Step 15

14 | Repair a short from CKT AB900 or AB950 to XB901 or XB950. Is the repair complete? | -- | Go to Step 19 | --
15 |

1. Turn the ignition switch to the OFF position.
2. Wait one minute until the SDM energy reserve capacitors have discharged.
3. Disconnect the negative battery cable. Refer to

   Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

   .
4. Remove the front passenger seat. Refer to Seat Replacement .
5. Disconnect the passenger seat belt side buckle pretensioner orange 2-way integral harness connector.
6. Use the J 39200 Digital Multimeter to measure the resistance between the passenger pretensioner yellow 2-way integral harness connector terminal 1 and 2.

Is the resistance reading less than the specified value?

OL

Go to Step 16

Go to Step 17

16 | Repair a short from CKT AB900 or AB950 to XB901 or XB950. Is the repair complete? | -- | Go to Step 19 | --
17 |

1. Use the J 38715-30 adapter to connect the J 38715-A SIR Driver/Passenger Load Tool PASSENGER INFLATOR connector to the pretensioner orange 2-way integral harness connector.
2. Reconnect the 8-way body harness-to-passenger seat connector C316 to the 8-way passenger seat connector.
3. Reconnect the SDM harness connector to the SDM.
4. Reconnect the negative battery cable.
5. Turn the ignition switch to the ON position.
6. Use the scan tool to request the SIR data list display.
7. Read the passenger pretensioner loop resistance RH PRETENS RESIST.

Is RH PRETENS RESIST. less than the specified value?

1.0 ohms

Go to Integrity Check

Go to Step 18

18 | Replace the passenger seat belt side buckle pretensioner. Refer to Seat Belt Side Buckle Pretensioner Replacement - Pass. . Has the passenger seat belt side buckle pretensioner been replaced? | -- | Go to Step 19 | --
19 | 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? | -- | Go to Step 19 | --
20 | Clear the SIR diagnostic trouble codes. Are the SIR diagnostic trouble codes cleared? | -- | Go to SIR Diagnostic System Check | --