For 1990-2009 cars

### Circuit Description

When the ignition switch is turned to ON, the sensing and diagnostic module (SDM) will perform a turn-on test to diagnose critical malfunctions within the SDM itself.

These test ignition and deployment loop voltages are measured to ensure that they are within their normal voltage ranges. The SDM monitors the voltages at the driver low and the passenger low to detect shorts to ground or voltage in the deployment loops.

If the warning lamp operates properly ON and OFF, the SDM measures the voltage continuously from the warning lamp terminal.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2500 Inflatable Restraint System Indicator Circuit

### Conditions for Running the DTC

Ignition voltage is within the normal operating voltage range.

### Conditions for Setting the DTC

The warning lamp does not blink properly ON and OFF.

### Action Taken When the DTC Sets

The SDM commands the AIR BAG indicator ON.

### Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.

### Reference

When the ignition switch is turned ON, the warning lamp blinks 7 times during 7 seconds.

If the warning lamp stays ON or blinks a second after the above normal blinking, 7 times during 7 seconds, then it is regarded as a defect, old or current. Please inspect the defect with the scan tool.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Caution: Refer to Sensing and Diagnostic Module Handling Caution in the Preface section. Caution: Refer to Sensing and Diagnostic Module Voltage after Ignition is Turned Off Caution in the Preface section. Schematic Reference: SIR Schematics Connector End View Reference: SIR Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Inspect fuse F4. Is the fuse open? | -- | Go to Step 3 | Go to Step 4
3 | Replace fuse F4. Is the repair complete? | -- | Go to Step 15 | --
4 |

1. Confirm the ignition switch is ON.
2. Measure the voltage from fuse F4.

Is the voltage within the specified range?

11-14 V

Go to Step 6

Go to Step 5

5 | Repair the power supply and the wiring to fuse F4. Is the repair complete? | -- | Go to Step 15 | --
6 |

1. Confirm the ignition switch is OFF.
2. Remove the instrument cluster or clock.
3. Inspect the bulb of the air bag warning lamp.

Is the bulb OK?

--

Go to Step 8

Go to Step 7

7 | Replace the bulb of the air bag warning lamp. Is the repair complete? | -- | Go to Step 15 | --
8 |

1. Confirm the ignition switch is ON.
2. Measure the voltage from terminal B15 of the cluster wiring connector.

Is the voltage within the specified range?

11-14 V

Go to Step 10

Go to Step 9

9 | Repair the wiring between fuse F4 and terminal B15 of the cluster wiring connector. Is the repair complete? | -- | Go to Step 15 | --
10 | Inspect the connection between terminal B15 and B7 of the cluster. Is the connection OK? | -- | Go to Step 12 | Go to Step 11
11 | Replace the instrument cluster. Refer to Instrument Cluster Replacement . Is the repair complete? | -- | Go to Step 15 | --
12 |

1. Confirm the ignition switch is OFF.
2. Remove the connector of the instrument panel (I/P) module and the connector of steering wheel module coil.
3. Remove the connector of the sensing and diagnostic module (SDM).
4. Confirm the ignition switch is ON.
5. Carefully lift the shorting bar from terminal 27 of the SDM connector and measure the voltage.

Is the voltage within the specified range?

11-14 V

Go to Step 13

Go to Step 14

13 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Is the repair complete? | -- | Go to Step 15 | --
14 | Repair the wiring between terminal 27 of the SDM and the instrument cluster. Is the repair complete? | -- | Go to Step 15 | --
15 |

1. Reconnect all SIR components.
2. Verify that all components, connectors and connector position assurances (CPAs) are properly mounted.
3. Use the scan tool in order to clear the DTCs.
4. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK