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 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 service wait time is 1 minute. Refer to On-Vehicle Service for enable/disable procedures

### Conditions for Setting the DTC

The passenger deployment loop resistance is more than 5.0 ohms. The passenger deployment loop consists of the following components:

• | The inflatable restraint I/P module.

• | The harness wiring of CKT BA10.

• | The harness wiring of CKT BP10.

• | 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 inflatable restraint I/P module circuit is less than 5.0 ohms, a Current DTC 33 will change to a History DTC 33, 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 inflatable restraint I/P module integral 2-way connector.

• | The SDM terminals 3 and 4.

• | The wire to terminal connections in CKT BA10.

• | The wire to terminal connections in CKT BP10.

Inspect CKTs BA10 and BP10 carefully for cutting and/or chafing. The diagnostic table directs the technician to note the entry value of the PASSENGER AIR BAG RES. Comparing the value of the PASSENGER AIR BAG RES. 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 General Electrical Diagnosis Procedures in Wiring Systems. 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 SDM.

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

3. This test isolates the malfunction to one side of the inflatable restraint IP module yellow 2-way connector. This is done by substituting the known good resistance of the load tool and then, observing if the malfunction is still present.

4. This test determines whether the malfunction is in CKT BA10.

5. This test determines whether the malfunction is in CKT BP10.

#### DTC 33 Pass. Air Bag Deploy. Loop Resistance High

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 DLC.
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 frontal air bag deployment loop resistance PASSENGER AIR BAG RES.

Has PASSENGER AIR BAG RES. 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 inflatable restraint IP module. Refer to Inflatable Restraint Instrument Panel Inflator Module .
5. Check for proper connection at terminals 1 and 2 on the harness side of the inflatable restraint IP module orange 2-way connector.

Are the terminals damaged or corroded?

--

Go to Step 4

Go to Step 5

4 | Repair the inflatable restraint IP module yellow 2-way harness connector. Refer to SIR Connector (Plastic Body and Terminal Metal Pin) Repair in this section. Are the repairs complete? | -- | Go to Step 5 | --
5 | Check for proper connection at terminals 1 and 2 on the inflatable restraint IP module yellow 2-way connector. Are the terminals damaged and/or corroded? | -- | Go to Step 6 | Go to Step 7
6 | Replace the inflatable restraint IP module. Refer to Inflatable Restraint Instrument Panel Inflator Module . Is the replacement complete? | -- | Go to Step 18 | --
7 |

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 inflatable restraint Sensing and Diagnostic and Seat Belt Pretensioner Module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic and Seat Belt Pretensioner Module Replacement .
5. Check for proper connection at terminals 3 and 4 on the SDM harness connector.

Are the terminals damaged and/or corroded?

--

Go to Step 8

Go to Step 10

8 | Replace the IP harness. Is the replacement complete? | -- | Go to Step 9 | --
9 | Check for proper connection at terminals 3 and 4 on the SDM. Are the terminals damaged or corroded? | -- | Go to Step 11 | Go to Step 18
10 | Check for proper connection at terminals 3 and 4 on the SDM. Are the terminals damaged or corroded? | -- | Go to Step 11 | Go to Step 12
11 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic and Seat Belt Pretensioner Module Replacement . Is the replacement complete? | -- | Go to Step 18 | --
12 |

1. Use the J 38715-45 adapter to connect the J 38715-A SIR Driver/Passenger Load Tool PASSENGER INFLATOR connector to the inflatable restraint IP module harness connector.
2. Reconnect the SDM harness connector to the SDM.
3. Reconnect the negative battery cable.
4. Turn the ignition switch to the ON position.
5. Use the scan tool to request the SIR data list display.
6. Read the passenger air bag deployment loop resistance PASSENGER AIR BAG RES.

Is PASSENGER AIR BAG RES. greater than the specified value?

5.0 ohms

Go to Step 14

Go to Step 13

13 |

1. Turn the ignition switch to the OFF position.
2. Replace the inflatable restraint IP module. Refer to Inflatable Restraint Instrument Panel Inflator Module .

Is the replacement complete?

--

Go to Step 18

--

14 |

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 SDM. Refer to On-Vehicle Service in this section.
5. Insert the J 42113 Shorting Bar Tool into the SDM harness connector terminal above terminals 3 and 4. This opens the short circuit bridge between terminals 3 and 4.
6. Zero the J 39200 Digital Multimeter.
7. Use the Zero the J 39200 Digital Multimeter to measure the resistance from the SDM harness connector terminal 3 to the inflatable restraint IP module yellow 2-way harness connector terminal 2.

Is the resistance reading within the specified values?

0-0.5 ohms

Go to Step 16

Go to Step 15

15 | Repair an open circuit or high resistance in CKT BA10. Is the repair complete? | -- | Go to Step 18 |
16 |

1. Zero the J 39200 Digital Multimeter.
2. Use the Zero the J 39200 Digital Multimeter to measure the resistance from the SDM harness connector terminal 4 to the inflatable restraint IP module yellow 2-way harness connector terminal 1.

Is the resistance reading within the specified values?

0-0.5 ohms

Go to Integrity Check

Go to Step 17

17 | Repair an open circuit or high resistance in CKT BP10. Is the repair complete? | -- | Go to Step 18 | --
18 | Reconnect all the SIR system components. Ensure all the SIR system components are properly mounted. Are all the SIR system components reconnected and are all the SIR system components properly mounted? | -- | Go to Step 19 | --
19 | Clear the SIR diagnostic trouble codes. Are all the SIR diagnostic trouble codes cleared? | -- | Go to SIR Diagnostic System Check | --