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

### Circuit Description

When the ignition switch is turned to the ON position, the inflatable restraint sensing and diagnostic and seat belt pretensioner module (SDM) performs tests to diagnose critical malfunctions within itself. The SDM monitors the six deployment loops to detect leakage currents to B+ in the frontal air bag deployment loops, the side air bag deployment loops and the seat belt pretensioner deployment loops. Then, the SDM proceeds with the RESISTANCE MEASUREMENT test to measure the deployment loop resistances to ensure they are within their respective normal resistance ranges. Upon passing these tests, the energy reserve is charged and the firing transistors are tested. The SDM then goes into CONTINUOUS MONITORING mode. The SDM service wait time is 1 minute. Refer to ENABLE/DISABLE procedures.

### Conditions for Setting the DTC

• | The ignition is within normal operating voltage range.

• | The measured leakage currents to voltage are above a specified value caused by a short to voltage in the inflatable restraint side impact module (LH) deployment loop.

### Action Taken When the DTC Sets

• | The SDM sets a DTC 76.

• | 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 76 to set are no longer present, History DTC 76 will set. History DTC 76 may be cleared using the scan tool.

### Diagnostic Aids

A short to voltage in the inflatable restraint side impact module (LH) deployment loop can cause an intermittent condition. Inspect CKT XB100 and CKT AB11 carefully for cutting and/or chafing. A careful inspection of the circuitsand components indicated on the DTC 76 table is essential to make sure that the replacement SDM will not be damaged.

### Test Description

The numbers below refer to step numbers on the diagnostic table.

1. This step checks to see if the inflatable restraint side impact module (LH) is defective.

2. This step checks to see if terminal 10 or terminal 11 of the SDM wiring harness connector is damaged or corroded.

3. This step checks for a short to B+ in CKT XB100.

4. This step determines if there is a short to B+ in CKT AB11 or if there is a malfunctioning SDM.

#### DTC 76 Inflatable Restraint Side Impact Module (LH) Deployment Loop Short to Voltage

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. Remove the ignition key from the ignition switch.
3. Wait 1 minute for the SDM energy reserve capacitors to discharge.
4. Disconnect the inflatable restraint side impact module (LH) yellow 2-way connector located under the LH seat track cover. Refer to Inflatable Restraint Seat Module Replacement - Driver .
5. Use the J 38715-55 adaptor to connect the J 38715-A SIR Driver/Passenger Load Tool to the inflatable restraint side impact module (LH) wiring harness connector.
6. Turn the ignition switch to the ON position.
7. Install the scan tool.
8. Use the scan tool to request the SIR DTC display.

Is DTC 76 current?

--

Go to Step 4

Go to Step 3

3 |

1. Turn the ignition switch to the OFF position.
2. Remove the ignition key from the ignition switch.
3. Wait 1 minute for the SDM energy reserve capacitors to discharge.
4. Replace the the inflatable restraint side impact module (LH). Refer to Inflatable Restraint Seat Module Replacement - Driver .

Is the repair complete?

--

Go to Step 13

--

4 |

1. Turn the ignition switch to the OFF position.
2. Remove the ignition key from the ignition switch.
3. Wait 1 minute for the SDM energy reserve capacitors to discharge.
4. Remove the J 38715-A SIR Driver/Passenger Load Tool.
5. 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 .
6. Check terminal 10 and terminal 11 of the SDM wiring harness connector for damaged terminals or corrosion.

Are the SDM wiring harness connector terminals damaged or corroded?

--

Go to Step 5

Go to Step 7

5 | Use the J 42250 Catera Terminal Repair Kit to repair the SDM wiring harness connector. Is the repair complete? | -- | Go to Step 6 | --
6 | Check for a proper connection at terminal 10 and terminal 11 of the SDM. Are the SDM terminals damaged or corroded? | -- | Go to Step 8 | Go to Step 13
7 | Check for a proper connection at terminal 10 and terminal 11 of the SDM. Are the SDM terminals damaged or corroded? | -- | Go to Step 8 | Go to Step 9
8 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic and Seat Belt Pretensioner Module Replacement . Is the repair complete? | -- | Go to Step 13 | --
9 |

1. Install the J 42113 SIR Shorting Bar Tool into the SDM wiring harness connector above terminal 10 and terminal 11.
2. Turn the ignition switch to the ON position.
3. Use the J 39200 Digital Multimeter (DMM) to measure the voltage between terminal 10 of the SDM wiring harness connector and a known good ground.

Is the measured voltage more than the specified value?

1 V

Go to Step 10

Go to Step 11

10 |

1. Locate a short to B+ in CKT XB100.
2. Repair the short to B+ in CKT XB100.

Is the repair complete?

--

Go to Step 13

--

11 | Use the J 39200 Digital Multimeter (DMM) to measure the voltage between terminal 11 of the SDM wiring harness connector and a known good ground. Is the measured voltage more than the specified value? | 1 V | Go to Step 12 | Go to Sensing and Diagnostic Module Integrity Check
12 |

1. Locate a short to B+ in CKT AB11.
2. Repair the short to B+ in CKT AB11.

Is the repair complete?

--

Go to Step 13

--

13 | Reconnect all the SIR components, making sure all the components are properly mounted. Have all SIR components been reconnected and properly mounted? | -- | Go to Step 14 | --
14 | Use the scan tool to clear all current and history SIR DTCs. Have all current and history SIR DTCs been cleared? | -- | Go to SIR Diagnostic System Check | --