K6JRF at the mic K6JRF's Page
formerly W6FZC

My Mercedes Benz
S500 Coupe

K6JRF's MB S500 Cpe
(New: May 4, 2001)

Analyze and Troubleshoot "Check Engine" MIL and Electronic Control Units (ECU)!

Supplemental Restraint System (SRS)

Description, Operation and Location
SRS Major Parts Location The airbag/Supplemental Restraint system (SRS) includes the driver's and passenger's airbags. This systems also includes the Emergency Tension Restraint (ETR) seat belts.

The driver' airbag is located beneath the steering wheel pad and inflates in 25 milliseconds. The passenger's airbag is located inside the upper right hand side of the instrument panel. The folded airbag and tubular gas generator are located inside a plastic housing. The airbag is made of nylon material with gas permeable sides.

If voltage is interrupted during a collision, the driver's and passenger's airbags will deploy within 100 milliseconds, but the ETR will not deploy. If vehicle voltage drops below 9.5V for longer than 10 seconds, the airbag system warning lamp will light. Once the voltage is greater than 10 volts, the lamp will go off.

The SRS control module (N2/2) is located on the transmission tunnel. This module process vehicle deceleration from an frontal impact. An arming switch is installed to interrupt the deployment circuit during normal driving mode. This allows for system deployment only when the limits have been exceeded.

The control module detects longitudinal vehicle deceleration and generates a signal that is processed and sent to the threshold evaluation switch. When the limit is exceeded, information is given to the ETR and SRS for proper deployment sequence.

Fault Table, DTC Readout, SRS Control module (N2/2)

Socket 1: Black (ground)
Socket 3: Red (12V)
Socket 30: Yellow (SRS output)

* DTC readout '10' means that the airbag deployment circuits in the control module have been activated. The DTC readout can not be erased. The Control Module must be replaced

DTC Possible Cause
1 No faults in system
2 SRS control module (N2/2)
3 Driver airbag squib (R12/3)
4 Front passenger airbag squib (R12/8)
5 Driver seat belt buckle switch (S68/3)
6 Front passenger seat belt buckle switch (S68/4)
7 Front passenger airbag resistor
8 Voltage supply
9 SRS warning lamp (A1e15) or insufficient time to read out the DTC memory or erase DTCs
10* SRS control module (N2/2)

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