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

### Circuit Description

When you turn the ignition switch to the ON position, the inflatable restraint Sensing and Diagnostic Module (SDM) performs tests in order to diagnose critical malfunctions. Next, the SDM measures IGNITION 1 voltage, the 23-volt loop reserve, and the deployment loop voltages in order to verify the normal ranges. The SDM proceeds with Continuous Monitoring. The SDM contains a network of resistors that is connected to 5 volts, to ground, and to the SDM sensor signal terminal 2. The 8.45K ohm resistor in the inflatable restraint forward discriminating sensor is parallel to the normally open switch, and provides a parallel path to ground. This causes a specified percentage of voltage to appear at the SDM Sensor Feed input. The SDM monitors this voltage in order to detect an open sensor or a short to voltage.

### Conditions for Setting the DTC

• | The SDM has an inflatable restraint forward discriminating sensor.

• | The voltage at Sensor Feed terminal 2 is more than 4.5 volts for 500 milliseconds.

The Continuous Monitoring test checks for this DTC. This test occurs if IGNITION 1 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 DTC

| The voltage at Sensor Feed terminal 2 is less than 4.5 volts for 500 milliseconds.

• | History DTC

- | Use a scan tool in order to clear the DTC.

- | 250 ignition cycles have occurred without a malfunction.

### Diagnostic Aids

Damaged wiring to the inflatable restraint forward discriminating sensor can cause an intermittent condition. Carefully inspect the sensor input and the ground circuits for broken wires or for chafed wires.

When measurements are requested in this table, use the J 39200 Digital Multimeter with the correct terminal adapter from the J 35616 Connector Test Adapter Kit. When a check for proper connection is requested, refer to Intermittents and Poor Connections in Electrical Diagnosis. When a wire, connector or terminal repair is requested, use the J-38125 Terminal Repair Kit and refer to Wiring Repair .

### Test Description

Caution: Be careful when you handle a sensor. Do not strike or jolt a sensor. Before applying power to a sensor:

• | Remove any dirt, grease, etc. from the mounting surface.

• | Position the sensor horizontally on the mounting surface.

• | Point the arrow on the sensor toward the front of the vehicle.

• | Tighten all of the sensor fasteners and sensor bracket fasteners to the specified torque value.

Failure to follow the correct procedure could cause air bag deployment, personal injury, or unnecessary SIR system repairs.

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

1. This test checks for correct contact and/or for corrosion of the yellow 2-way connector.

2. This test checks for a malfunction of the inflatable restraint forward discriminating sensor.

3. This test checks for an open in the sensor ground circuit.

4. This test checks for the correct contact and/or for corrosion of the connector of the Sensing and Diagnostic Module (SDM).

5. This test checks for an open in the sensor input circuit.

6. This test checks for a short to voltage in the sensor input circuit.

#### DTC B1036 Disc Sensor Circuit Open or Short to Voltage

Step | Action | Values | 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. Disconnect the inflatable restraint forward discriminating sensor.
3. Check for the correct connection at terminal 1 and at terminal 2 on the harness connector of the inflatable restraint forward discriminating sensor.

Are the terminals damaged or corroded?

--

Go to Step 3

Go to Step 5

3 | Replace the harness connector of the inflatable restraint forward discriminating sensor. Refer to SIR Connector (Plastic Body and Terminal Metal Pin) Repair portion of Wiring Repair . Did you replace the harness connector? | -- | Go to Step 4 | --
4 | Check for the correct connection at terminal 1 and at terminal 2 on the connector of the inflatable restraint forward discriminating sensor. Are the terminals damaged or corroded? | -- | Go to Step 6 | Go to Step 19
5 | Check for the correct connection at terminal 1 and at terminal 2 on the connector of the inflatable restraint forward discriminating sensor. Are the terminals damaged or corroded? | -- | Go to Step 6 | Go to Step 7
6 | Replace the inflatable restraint forward discriminating sensor. Refer to Inflatable Restraint Front End Discriminating Sensor Replacement . Has the sensor been replaced? | -- | Go to Step 21 | --
7 | Measure the resistance from terminal 1 to terminal 2 of the inflatable restraint forward discriminating sensor. Is the resistance reading more than the specified value? | 8.54 Kohms | Go to Step 6 | Go to Step 8
8 | Measure the resistance from terminal 1 of the harness connector of the inflatable restraint forward discriminating sensor to ground. Is the resistance reading within the specified value? | 0-5 ohms | Go to Step 10 | Go to Step 9
9 | Repair an open condition in the GRY/BLK wire. Is the circuit repair complete? | -- | Go to Step 21 | --
10 |

1. Remove the AIR BAG Fuse.
2. Disconnect the yellow connectors of the inflatable restraint steering wheel module and of the inflatable restraint IP modules near the base of the steering column and behind the IP compartment.
3. Disconnect the Sensing and Diagnostic Module (SDM).
4. Check for a correct connection at terminal 2 on the harness side of the SDM connector.

Is the SDM harness connector damaged or corroded?

--

Go to Step 11

Go to Step 13

11 | Replace the SDM harness connector. Refer to SIR Connector (Plastic Body and Terminal Metal Pin) Repair portion of Wiring Repair . Did you replace the SDM harness connector? | -- | Go to Step 12 | --
12 | Check for a correct connection at terminal 2 on the SDM. Is the SDM terminal damaged or corroded? | -- | Go to Step 14 | Go to Step 19
13 | Check for a correct connection at terminal 2 on the SDM. Is the SDM terminal damaged or corroded? | -- | Go to Step 14 | Go to Step 15
14 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Did you replace the SDM? | -- | Go to Step 19 | --
15 | Measure the resistance on harness connector terminal 2 of the SDM to terminal 2 of the harness connector of the inflatable restraint forward discriminating sensor. Is the resistance reading within the specified values? | 0-5 ohms | Go to Step 17 | Go to Step 16
16 | Repair an open condition in the GRY wire. Is the circuit repair complete? | -- | Go to Step 19 | --
17 |

1. Install the AIR BAG Fuse.
2. Turn the ignition switch to ON.
3. Measure the voltage on the harness connector of the inflatable restraint forward discriminating sensor from terminal 2 to ground.

Is the measured voltage less than the specified value?

1 V

Go to Sensing and Diagnostic Module Integrity Check

Go to Step 18

18 |

1. Turn the ignition switch to the OFF position.
2. Remove the AIR BAG Fuse.
3. Repair a short to B+ condition in the GRY wire.

Is the circuit repair complete?

--

Go to Step 19

--

19 | Reconnect and mount all the SIR system components. Are all the SIR components reconnected and correctly mounted? | -- | Go to Step 20 | --
20 | Replace the AIR BAG Fuse. Did you replace the AIR BAG Fuse? | -- | Go to Step 22 | --
21 | Reconnect and mount all the SIR system components. Are all the SIR components reconnected and correctly mounted? | -- | Go to Step 22 | --
22 | Clear the SIR diagnostic trouble codes. Did you clear the SIR diagnostic trouble codes? | -- | Go to SIR Diagnostic System Check | --