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 may reset the front end sensor up to two times by removing and reapplying power to it. If the fault is still present, the SDM will set a diagnostic trouble code (DTC).
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC B0083 Front End Sensor 1 (Left) |
| • | DTC B0084 Front End Sensor 2 (Right) |
This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description .
DTC Symptom | DTC Symptom Descriptor |
|---|---|
01 | Front End Sensor Short To Battery |
02 | Front End Sensor Short To Ground |
04 | Front End Sensor Open Circuit |
39 | Front End Sensor Internal Electronic Failure |
71 | Front End Sensor Invalid Serial Data Received |
0F | Front End Sensor Erratic |
3A | Front End Sensor Incorrect Component Installed |
Conditions for Running the DTC
Ignition 1 voltage is within the normal operating voltage range of 9-16 volts.
Conditions for Setting the DTC
All of the following conditions exist for 2.5 seconds:
B0083 01 or B0084 01
| • | The front end sensor has been shorted to voltage. |
| • | The SDM has not received a message from the front end sensor for more than 375 milliseconds. |
B0083 02 or B0084 02
| • | The front end sensor has been shorted to ground. |
| • | The front end sensor current has been above 23 mA for longer than 5 milliseconds. |
B0083 04 or B0084 04
The front end sensor circuit is open.
B0083 39 or B0084 39
| • | The SDM has received a NOK message from the front end sensor. |
| • | The SDM has not received a message. |
B0083 71 or B0084 71
The SDM has received invalid serial data from the front end sensor.
B0083 0F or B0084 0F
The SDM has received erratic messages from the front end sensor.
B0083 3A or B0084 3A
| • | 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 the correct ID message. |
Action Taken When the DTC Sets
The SDM commands ON the AIR BAG warning lamp via GMLAN serial data.
Conditions for Clearing the MIL/DTC
| • | The DTC will clear when 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:
| • | An open in the front end sensor circuit |
| • | 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 |
| • | An internal failure in the front end sensor |
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 .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
Tests the front end sensor signal and front end sensor voltage circuits for high or low resistance or open
-
Tests between the front end sensor signal and front end sensor voltage circuits for continuity
-
Tests the front end sensor signal and front end sensor voltage circuits for a short to voltage or ground.
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 | |
2 |
Important: CANdi module EL-39021-460 must be used with the scan tool. Does the scan tool indicate that DTC B0083-B0084 is current? | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections |
3 |
Does the connector exhibit any signs of damage or corrosion? | Go to Step 4 | Go to Step 5 |
4 |
Did you complete the repair? | Go to Step 11 | -- |
5 |
Does the connector exhibit any signs of damage or corrosion? | Go to Step 6 | Go to Step 7 |
6 |
Did you complete the repair? | Go to Step 11 | -- |
Did you find and correct the condition? | Go to Step 11 | Go to Step 8 | |
Test for continuity between the front end sensor signal and voltage circuits on the SDM connector. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 11 | Go to Step 9 | |
Did you find and correct the condition? | Go to Step 11 | Go to Step 10 | |
10 |
Did you complete the replacement? | Go to Step 11 | -- |
11 |
Does the DTC reset? | Go to Step 12 | System OK |
12 |
Did you complete the replacement? | Go to Step 13 | -- |
13 |
Does the DTC reset? | Go to Step 2 | System OK |
