GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2005 🢒 Grand Prix 🢒 Accessories 🢒 Navigation Systems 🢒 DTC B0103, B0104, or B0105

Circuit Description

The inflatable restraint front end sensor, also known as the electronic frontal sensor (EFS), utilizes a unidirectional 2-wire circuit. The front end sensor modulates current on the interface to send ID, State of Health, and deployment commands to the inflatable restraint sensing and diagnostic module (SDM). The SDM serves as a power source and a ground for the front end sensor. When the ignition is turned on and input power from the SDM is first detected, the front end sensor responds by performing internal diagnostics and sending an ID to the SDM. The SDM considers the ID to be valid if the response time is less than 5 seconds. The front end sensor continually communicates status messages to the SDM, which determines if a fault is present in the front end sensor circuit. When a fault is detected, the SDM resets the front end sensor twice by removing and reapplying power to it. If the fault is still present, the SDM will set a diagnostic trouble code (DTC). Some vehicles may refer to electronic frontal sensor 2 but only contain 1 electronic frontal sensor.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC B0103 Front End Sensor 2 Performance
    • DTC B0104 Discard Front End Sensor 2
    • DTC B0105 Incorrect Front End Sensor 2 Installed

Conditions for Running the DTC

Ignition voltage is within the normal operating voltage range.

Conditions for Setting the DTC
    • DTC B0103 for the front end sensor will set when one of the following conditions occur:
       - A valid ID message is not received within 5 seconds of the front end sensor being powered up.
       - Status message is not received.
       - The SDM has reset the front end sensor twice without detecting a valid ID message.
    • DTC B0104 for the front end sensor will set when the SDM has received a NOK message from the front end sensor.
    • DTC B0105 for the front end sensor will set when one of the following conditions occur:
       - The SDM has received an ID message from the front end sensor which does not match the ID stored in the SDM memory.
       - The SDM has reset the front end sensor twice without detecting a correct ID message.

Action Taken When the DTC Sets

The SDM commands ON the AIR BAG warning lamp via class 2 serial data.

Conditions for Clearing the DTC
    • The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.
    • A history DTC will clear once 255 malfunction free ignition cycles have occurred.

Diagnostic Aids

The following are conditions that may cause the malfunction:

    • A short to ground or voltage in the front end sensor circuit
    • High or low resistance in the front end sensor circuit
    • Improper front end sensor installed on vehicle

Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and connectors may result in misdiagnosis, causing a part replacement with the reappearance of the malfunction. If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

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

  1. This step tests the front end sensor signal and front end sensor voltage circuits for an open or high resistance.

    2.

  2. This step tests between the front end sensor signal and front end sensor voltage circuits for continuity.

    3.

  3. This step tests the front end sensor signal and front end sensor voltage circuits for a short to voltage.

Step

Action

Yes

No

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 in Vehicle DTC Information

2
  1. Install A scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Use the scan tool to request SIR DTCs displayed.

Does the scan tool indicate that DTC B0104 or B0105 is current?

Go to Step 10

Go to Step 3

3

  1. Turn OFF the ignition.
  2. If DTC B0103 is current, disconnect the front end sensor also known as the electronic frontal sensor (EFS) connector. Refer to Inflatable Restraint Front End Sensor Replacement .
  3. If DTC B0104 or B0105 is current, replace the front end sensor. Refer to Inflatable Restraint Front End Sensor Replacement .
  4. Inspect both the component and harness sides of the connector for damage or corrosion. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Does the connector exhibit any signs of damage or corrosion?

Go to Step 4

Go to Step 5

4
  1. If the component side of the front end sensor connector is damaged, the front end sensor must be replaced. Refer to Inflatable Restraint Front End Sensor Replacement .
  2. If the harness side of the front end sensor connector is damaged, replace the harness side of the connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 11

--

5
  1. Turn OFF the ignition.
  2. Disconnect the inflatable restraint sensing and diagnostic module (SDM) connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Inspect both the component and harness sides of the SDM connector for damage or corrosion. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Does the connector exhibit any signs of damage or corrosion?

Go to Step 6

Go to Step 7

6
  1. If the component side of the SDM connector is damaged, the SDM must be replaced. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.
  2. If the harness side of the SDM connector is damaged, replace the harness side of the connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 11

--

7

  1. If DTC B0103 is current, disconnect the front end sensor connector.
  2. Test both the front end sensor signal and front end sensor voltage circuits for an open or high resistance between the SDM connector and the front end sensor connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 8

8

Test for continuity between the front end sensor signal circuit and the front end sensor voltage circuit on the SDM connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 9

9

  1. Turn ON the ignition, with the engine OFF.
  2. Test both front end sensor signal and front end sensor voltage circuits for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 10

10
  1. Turn OFF the ignition.
  2. If DTC B0103, B0104, or B0105 was current replace the front end sensor. Refer to Inflatable Restraint Front End Sensor Replacement .

Did you complete the replacement?

Go to Step 11

--

11
  1. Reconnect all SIR components.
  2. Use the scan tool in order to Clear the DTCs.
  3. Operate the vehicle within the Conditions for Running the DTC as specified in the text.

Does the DTC reset?

Go to Step 12

System OK

12
  1. Turn OFF the ignition.
  2. Replace the SDM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 13

--

13
  1. Turn ON the ignition, with the engine OFF
  2. Use the scan tool in order to Clear the DTCs.
  3. Operate the vehicle within the Conditions for Running the DTC as specified in the text.

Does the DTC reset?

Go to Step 2

System OK