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

### Circuit Description

When you first turn the ignition switch to the ON position, the inflatable restraint Sensing and Diagnostic Module (SDM) performs tests to diagnose critical malfunctions within itself. Upon passing these tests IGNITION 1, 23 VLR and deployment loop voltages are measured to make sure they are within their respective normal voltage ranges. The SDM monitors the voltages at DRIVER SIDE LOW terminal 10 and PASSENGER SIDE LOW terminal 3 to detect shorts to B+ in the inflator module circuits. The service wait time is 10 minutes. Refer to Disabling the SIR System .

### Conditions for Setting the DTC

• | The voltage at the PASSENGER SIDE LOW terminal 3 is less than 3.5 volts.

• | The voltage at DRIVER SIDE LOW terminal 10 is more than 3.5 volts for 500 milliseconds.

The CONTINUOUS MONITORING test checks this DTC. This test occurs when IGNITION 1 is within the normal operating voltage range.

### Action Taken When the DTC Sets

• | The SDM sets DTC B1025 and also DTC B1071.

• | The SDM turns ON the AIR BAG warning lamp.

### Conditions for Clearing the DTC

DTC B1025 is a latched code. You cannot clear a latched code. Repair the malfunction that set this DTC before you replace the SDM.

### Diagnostic Aids

A short-to-B+ in the inflatable restraint steering wheel module circuit may cause an intermittent condition. A DTC B1025 would be accompanied by DTC B1071. Inspect the GRN/RED wire and the GRN wire carefully for cut or chafed wires. A careful inspection of circuits and components indicated on the DTC B1025 Table is essential to make sure that replacement SDM will not be damaged. The diagnostic table directs the technician to note the entry value of DRIVER SENSELO. Comparing the value of DRIVER SENSELO 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 in this section.

### DTC Table Test Description

Numbers below refer to step numbers on the diagnostic table.

1. This step determines the DRIVER SIDE LOW voltage measured by the inflatable restraint Sensing and Diagnostic Module (SDM).

2. This step isolates the malfunction to one side of the yellow 2-way connector on the inflatable restraint steering wheel module coil. This connector is located near the base of the steering column.

3. This step determines whether the malfunction is in the inflatable restraint steering wheel module coil or in the inflatable restraint steering wheel module.

4. This step determines whether the malfunction is in the GRN/RED wire.

5. This step determines whether the malfunction is in the GRN wire.

Notice: When DTC B1025 is set, it is necessary to replace the inflatable restraint Sensing and Diagnostic Module (SDM). Setting DTC B1025 also causes DTC B1071 to set. When a scan tool clear codes command is issued and the malfunction is no longer present, DTC B1025 and DTC B1071 will remain current. Ensure that the short to B+ condition is repaired prior to installing a replacement SDM in order to avoid damaging the SDM.

#### DTC B1025 Driver 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 LOCK position.
2. Connect a scan tool to the data link connector. Follow the directions in the instruction manual of the scan tool.
3. Turn the ignition switch to the ON position.
4. Request the SIR data list display.
5. Read the DRIVER SIDE LOW voltage DRIVER SENSELO. Record this value on the repair order.

Have you read and recorded DRIVER SENSELO?

--

Go to Step 3

--

3 |

1. Turn the ignition switch to the LOCK position.
2. Disconnect the yellow 2-way connectors on the inflatable restraint steering wheel module and the inflatable restraint IP module. These connectors are located near the base of the steering column and behind the IP compartment.
3. Connect the J 38715-A SIR Driver/Passenger Load Tool to the inflatable restraint steering wheel and to the inflatable restraint IP module harness connectors.
4. Turn the ignition switch to the ON position.
5. Using the scan tool, request the SIR data list display and read the DRIVER SIDE LOW voltage DRIVER SENSELO.

Is DRIVER SENSELO more than the specified value?

4.8 V

Go to Step 7

Go to Step 4

4 |

1. Turn the ignition switch to the LOCK position.
2. Remove the inflatable restraint steering wheel module from the steering wheel. Refer to Steering Wheel Inflator Module Replacement in Steering Wheel and Column.
3. Disconnect the J 38715-A from the 2-way connector at the base of the steering column.
4. Reconnect the 2-way connector at the base of the steering column.
5. Connect the J 38715-A to the inflator module connector on the steering column.
6. Turn the ignition switch to the ON position.
7. Using the scan tool, request the SIR data list display, and read the DRIVER SIDE LOW voltage DRIVER SENSELO.

Is DRIVER SENSELO more than the specified value?

4.8 V

Go to Step 6

Go to Step 5

5 |

1. Turn the ignition switch to the LOCK position.
2. Replace the inflatable restraint steering wheel module. Refer to Steering Wheel Inflator Module Replacement in Steering Wheel and Column.

Have you replaced the inflatable restraint steering wheel module?

--

Go to Step 11

--

6 |

1. Turn the ignition switch to the LOCK position.
2. Remove the inflatable restraint steering wheel module coil and inspect the connecting wires for damage.
3. Determine and repair the cause of damage. Then replace the inflatable restraint steering wheel module coil. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement - Off Vehicle in Steering Wheel and Column.

Have you replaced the inflatable restraint steering wheel module coil?

--

Go to Step 11

--

7 |

1. Turn the ignition switch to the LOCK position.
2. Disconnect the inflatable restraint Sensing and Diagnostic Module (SDM).
3. Disconnect the J 38715-A .
4. Turn the ignition switch to the ON position.
5. Measure the voltage on the SDM harness connector from terminal 9 to terminal 6 (ground).

Is the measured voltage less than the specified value?

1 V

Go to Step 9

Go to Step 8

8 |

1. Turn the ignition switch to the LOCK position.
2. Repair a short to B+ condition in the GRN/RED wire.

Is the circuit repair complete?

--

Go to Step 11

--

9 | Measure the voltage on the SDM harness connector from terminal 10 to terminal 6 (ground). Is the measured voltage less than the specified value? | 1 V | Go to Integrity Check | Go to Step 10
10 |

1. Turn the ignition switch to the LOCK position.
2. Repair a short to B+ condition in the GRN wire.

Is the circuit repair complete?

--

Go to Step 11

--

11 |

1. Reconnect and confirm that all of the SIR system components are properly mounted.
2. Turn the ignition switch to the ON position.
3. Confirm that DRIVER SENSELO is less than the specified value.

Are all the SIR components connected and properly mounted?

--

Go to SIR Diagnostic System Check

--