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

### 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 ground in the inflator module circuits.

### Conditions for Setting the DTC

• | The driver deployment loop is not open.

• | The passenger deployment loop is not open.

• | The driver deployment loop is not shorted to voltage.

• | The voltage at DRIVER SIDE LOW terminal 10 is more than 1.5 volts.

• | The voltage at the PASSENGER SIDE LOW terminal 3 is less than 1.5 volts for 500 milliseconds.

The following tests check for this DTC. These tests occur when IGNITION 1 is within the normal operating voltage range.

• | The POWER ON test--When the malfunction is detected in this test, The RESISTANCE MEASUREMENT test will not be performed.

• | The CONTINUOUS MONITORING Test.

### 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

• | Clear the Current DTC when the voltage at the PASSENGER SIDE LOW terminal 3 is more than 1.5 volts for 500 milliseconds.

• | Clear the History DTC under the following conditions:

- | You issue a scan tool CLEAR CODES command.

- | 250 malfunction free ignition cycles have occurred.

### Diagnostic Aids

A short-to-ground in the inflatable restraint (SIR) IP module circuit can cause and intermittent condition. Moving wires while monitoring PASSENGER SENSELO may help locate the fault. Inspect the YEL/RED wire and the YEL wire carefully for cut or chafed wires. Wiring pigtail damage requires replacement of the inflatable restraint IP module.

The diagnostic table directs the technician to note the entry value of PASSENGER SENSELO. Comparing the value of the PASSENGER 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.

### Test Description

Numbers below refer to step numbers on the diagnostic table.

1. This test determines the PASSENGER SIDE LOW voltage measured by inflatable restraint Sensing Diagnostic Module (SDM).

2. This test isolates the malfunction to one side of the inflatable restraint IP module yellow 2-way connector located behind the IP compartment.

3. This test determines whether the malfunction is in the YEL/RED wire.

4. This test determines whether the malfunction is in the YEL wire.

#### DTC B1018 Passenger Deployment Loop Short to GND

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 and record on the repair order the PASSENGER SIDE LOW voltage PASSENGER SENSELO.

Is the PASSENGER SENSELO less than the specified value?

3.3 V

Go to Step 3

Refer to Diagnostic Aids

3 |

1. Turn the ignition switch to the LOCK position.
2. Disconnect the inflatable restraint (SIR) steering wheel and inflatable restraint IP modules yellow 2-way connectors. These are located under the steering wheel side cap and behind the IP compartment.
3. Connect the J 38715-A to the inflatable restraint steering wheel and 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. Read the PASSENGER SIDE LOW voltage PASSENGER SENSELO.

Is the PASSENGER SENSELO less than specified value?

1.5 V

Go to Step 5

Go to Step 4

4 |

1. Turn the ignition switch to the LOCK position.
2. Inspect the inflatable restraint IP module pigtail for damage. Verify that the pigtail and the nearby wiring are routed correctly.
3. Replace the inflatable restraint IP module. Refer to Inflatable Restraint Instrument Panel Module Replacement in this section.

Did you replace the inflatable restraint IP module?

--

Go to Step 9

--

5 |

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. Measure the resistance on the SDM harness connector from terminal 4 to terminal 6 (ground).

Is the resistance reading less than the specified value?

OL

Go to Step 6

Go to Step 7

6 | Repair a short to ground condition in the YEL/RED wire. Refer to Wiring Repair . Are the repairs complete? | -- | Go to Step 9 | --
7 | Measure the resistance on the SDM harness connector from terminal 3 to terminal 6 (ground). Is the resistance reading less than the specified value? | OL | Go to Step 8 | Go to Integrity Check
8 | Repair a short to ground condition in the YEL wire. Is the circuit repair complete? | -- | Go to Step 9 | --
9 | Reconnect and confirm that all the SIR components are properly mounted. Did you reconnect and properly mount all the SIR components? | -- | Go to Step 10 | --
10 | Clear the SIR diagnostic trouble codes. Did you clear the SIR diagnostic trouble codes? | -- | Go to SIR Diagnostic System Check | --