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

### Circuit Description

When you first turn the ignition switch to the RUN position, the inflatable restraint Sensing and Diagnostic Module (SDM) performs tests to diagnose critical malfunctions within itself. Next the SDM measures IGNITION POSITIVE VOLTAGE, 23 VLR and the deployment loop voltages to make sure they are within their respective normal voltage ranges. Then the SDM proceeds to CONTINUOUS MONITORING. The SDM contains a resistor network connected to 5 volts, ground, and to the SDM front end sensor signal terminal 9. The 1.0 K ohm resistor in the inflatable restraint front end discriminating sensor parallel to the normally open switch provides a parallel path to ground. This causes a specified percentage of voltage to appear at the SDM front end sensor signal input. The SDM monitors this voltage to detect shorts to power or an open discriminating sensor.

### Conditions for Setting the DTC

• | The SDM is configured for an inflatable restraint front end discriminating sensor

• | The voltage at front end sensor signal terminal 9 is more than 5.0 volts for 500 milliseconds.

The CONTINUOUS MONITORING test checks for this DTC. This test occurs when IGNITION POSITIVE VOLTAGE 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 MIL/DTC

• | Current DTC

| The voltage at front end sensor signal terminal 9 is less than 3.2 volts for 500 milliseconds.

• | History DTC

- | You issue a scan tool CLEAR CODES command.

- | Once 250 malfunction free ignition cycles have occurred.

### Diagnostic Aids

A broken or chafed wire in the inflatable restraint front end discriminating sensor circuit can cause an intermittent condition. Inspect CKT 1834 and CKT 1751 carefully for cut or chafed wires.

When measurements are requested in this table, use the J 39200 DMM with the correct terminal adapter from the J 35616 Connector Test Adapter Kit. When an inspection for proper connection is requested, refer to Testing for Electrical Intermittents in Wiring Systems. When a wire, connector or terminal repair is requested, use the J-38125 Terminal Repair Kit and refer to Wiring Repairs in Wiring Systems.

### Test Description

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

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

2. This test checks for a malfunctioning discriminating sensor.

3. This test checks for an open in CKT 1751.

4. This test checks for proper contact or corrosion of the inflatable restraint Sensing and Diagnostic Module (SDM) connector.

5. This test checks for an open in CKT 1834.

6. This test checks for a short-to-B+ in CKT 1834.

#### DTC B1036 Disc Sensor CKT Open or 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. Disconnect the inflatable restraint front end discriminating sensor.
3. Check for proper connection at the sensor harness connector terminals A and B.

Are the terminals damaged or corroded?

--

Go to Step 3

Go to Step 5

3 | Replace the sensor harness connector. Refer to Wiring Repair . Are the repairs complete? | -- | Go to Step 4 | --
4 | Check for proper connection at the sensor connector terminals A and B. Are the terminals damaged or corroded? | -- | Go to Step 6 | Go to Step 19
5 | Check for proper connection at the sensor connector terminals A and B. Are the terminals damaged or corroded? | -- | Go to Step 6 | Go to Step 7
6 | Replace the inflatable restraint front end discriminating sensor. Refer to Inflatable Restraint Front End Discriminating Sensor Replacement . Are the repairs complete? | -- | Go to Step 19 | --
7 | Measure the resistance between the sensor connector terminals A and B. Is the resistance reading more than the specified value? | 1050 ohms | Go to Step 6 | Go to Step 8
8 | Measure the resistance from the sensor harness connector terminal B to ground. Is the resistance reading within the specified values? | 0-5 ohms | Go to Step 10 | Go to Step 9
9 | Repair an open condition in CKT 1751. Are the repairs complete? | -- | Go to Step 19 | --
10 |

1. Disconnect the inflatable restraint steering wheel and I/P module yellow 2-way connectors at the base of the steering column and above the RH sound insulator.
2. Disconnect the inflatable restraint Sensing and Diagnostic Module (SDM).
3. Check for proper connection at terminal 9 on the harness side of the SDM connector.

Is the connector damaged or corroded?

--

Go to Step 11

Go to Step 13

11 | Replace the SDM harness connector. Refer to Wiring Repair . Are the repairs complete? | -- | Go to Step 12 | --
12 | Check for proper connection at terminal 9 of the SDM. Is the terminal damaged or corroded? | -- | Go to Step 14 | Go to Step 19
13 | Check for proper connection at terminal 9 of the SDM. Is the terminal damaged or corroded? | -- | Go to Step 14 | Go to Step 15
14 | Replace the inflatable restraint Sensing and Diagnostic Module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Are the repairs complete? | -- | Go to Step 19 | --
15 | Measure the resistance between the sensor harness connector terminal A and the SDM harness connector terminal 9. 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 CKT 1834. Are the repairs complete? | -- | Go to Step 19 | --
17 |

1. Turn the ignition switch to the RUN position.
2. Measure the voltage on the sensor harness connector from terminal A to ground.

Is the measured voltage less than the specified value?

1.0 V

Go to Sensing and Diagnostic Module Integrity Check

Go to Step 18

18 |

1. Turn the ignition switch to the OFF position.
2. Repair a short-to-B+ condition in CKT 1834.

Are the repairs complete?

--

Go to Step 19

--

19 | Reconnect all the SIR system components, make sure all the components are properly mounted. Have all the SIR components been reconnected and properly mounted? | -- | Go to Step 20 | --
20 | Clear all the SIR DTCs. Have all the SIR DTCs been cleared? | -- | Go to SIR Diagnostic System Check | --