SRS - Airbag Technology
SOURCE: Hyundai Tech Net Times Volume 14 Issue 1 2004TITLE: Supplemental Restraint System
APPLIES TO: 2003 - 2004 Accent, and 2004 Elantrta
SERVICE TIP:
The December 2002 issue of TechNet Times discussed airbag technology. Since that time, additional system features have been added. The Santa Fe now offers side impact airbags (SAB) and the 2003-04 Accent and 2004 Elantra are equipped with dual-stage airbags. Let's look at the Accent.
Before performing any diagnosis it is important to determine which Supplemental Restraint System Control Module is installed in the particular vehicle you are diagnosing. Accents produced before January 6, 2003 are not equipped with side impact airbags. All 2003 and 2004 Accents manufactured for the U.S. are equipped with dual-stage airbags. The Accent 2003 and 2004 shop manuals include two systems, one not including dual-stage airbags (SRE-LC), and one with dual-stage airbags. U.S. vehicles use the dual-stage airbag system. The SRELC system is used in other countries.
The Accent's dual-stage airbag inflation is determined by the impact speed, seat belt usage and seat position. The driver (DAB) and the passenger (PAB) airbags both have dual circuits. The DAB has two separate connectors for the two circuits. The two connectors are of a different style and are not interchangeable. The connectors differ from connectors for previous models years. The PAB has only one connector with four pins (two for each circuit). The connector is located behind the center console, just to the left of the glove box. To access the connector, open the glove box, remove both glove box stoppers and lower the glove box.
The PAB connector has a red sliding secondary lock mechanism. To remove the connector, push the red locking clip to the left side (as shown in figure 1). After the secondary lock has been unfastened, the connector can be released completely by pushing down on the primary lock tab and separating the connector halves.
Seat Track Position Sensor:
The Seat Track Position Sensor (STPS) is located on the inside seat rail of both front seats. The STPS resistance changes depending on its location relative to a vane mounted on the seat rail. When the STPS is positioned over the vane (6 latching positions or more rearward of the forward-most position), its resistance is approximately 900 ohms. When it is positioned off of the vane (within 5 latching positions from the forwardmost position), the sensor's resistance is approximately 300 ohms. (The STPS resistance values are measured without requiring power to the circuit).
In the event of a frontal impact severe enough to deploy the airbags, if one of the front seats is placed within 5 latching positions from the forward-most position (STPS off of the vane), only the first stage circuit will be activated for that airbag. If the front seat is placed 6 latching positions or more rearward of the forward- most position (STPS over the vane), then the SRS Control Module will deploy the airbag with either the first or second stage circuit (depending on the seat belt usage and the severity of the impact). If there is a condition with the STPS where the SRSCM cannot determine the position of the seat, then a Seat Track Sensor Fault Code is generated and the SRS warning light will illuminate until erased from the SRSCM memory using from the SRSCM memory using a Hi-Scan Pro (The Fault Code will remain as a history code if the condition has been corrected). The table at the bottom of this page shows the deployment strategy of the dual-stage system:
Front Impact Sensors
The 2003 and 2004 Accents are equipped with two front impact sensors that are mounted on the radiator support panel on both sides of the radiator. The front impact sensor aids in the airbag deployment decision.
Side Impact Airbag (SAB) (If Equipped):
The side impact airbags (installed in both driver and passenger front seats) are the single output type. Side airbag equipped vehicles have "SRS Airbag" imprinted on the side of the front seats. The two satellite sensors are located at the bottom of the B-pillars, behind the seat belt pretensioner assembly.
NOTE: Any modification(s) of the seats may prevent proper operation of the side impact airbags when they are intended to deploy in a collision, which may result in serious injury or death.
See TSB # 01-90-012 ("Side Impact Airbags") for more details. For a complete listing of applicable Diagnostic Trouble Codes, parts and special tools, review TSB #03-90-021.