2003 E320 SRS Light on, brought to be fixed, did diagnosis, found cracked sensor pad on passenger side and replaced, switch also gone so replaced that too. Couldn't get the computer to reset once they did this so thought the SRS Unit needed to be replaced, replaced it, still nothing. Unable to communicate as the codes have been erased now... any thoughts?

Speculation without further details but 3 usual causes:
1. Clock spring in steering wheel for airbag open circuit.
To Test - disconnect battery-disconnect airbag ribbon from steering wheel -insert 3 -8ohm resistance bypass in airbag plug below steering column feeding clockspring. reconnect battery and see if light goes out after 5 seconds
2. Check passenger seat sensor operational.
To test - with ignition off - disconnect plug under passenger seat for sensor pad and insert test ohm resistance in feed plug. switch ignition on as test 1.
3. Check steering wheel button operation. if any radio actions do not work problem may be infrared link between steering wheel and radio (especially aftermarket modules)

There is no relay for the passenger side air bag . What seams to be the trouble ? There is possibly a code set in the air bag control module .
Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS) The air bag supplemental restraint system (SRS) is designed to provide increased collision protection for front seat and second row outboard occupants, in addition to that provided by the 3-point safety belt system. Safety belt use is necessary to obtain the best occupant protection and to receive the full advantage of the SRS.
This vehicle line contains dual stage deployment (advanced restraint system) driver and front passenger air bag modules. These vehicles are also equipped with driver and front passenger safety belt retractor pretensioners. These vehicles can also be equipped with optional side air curtains that deploy from the A-pillar to the C-pillar upon a side impact. Vehicles with optional side air curtains are also equipped with seat side air bag modules in the front seats.
Side air curtains deploy from the headliner, protecting the first and second row outboard occupants during a side impact. Seat side air bag modules deploy from the outboard front seat backrest upon a side impact. In addition, a front impact severity sensor is mounted to the lower radiator support, a seat position sensor is mounted to the driver seat and a usage detection switch is added to the front driver and passenger outboard buckles. If equipped with optional side air curtain modules and seat side air bag modules, there are an additional 4 side impact sensors.
Vehicles are also equipped with an occupant classification sensor (OCS) system as part of the front passenger seat. The OCS system includes 2 OCS rails and an OCS module.
Passenger Air Bag Deactivation (PAD) Indicator
The passenger air bag deactivation (PAD) indicator is a visual indicator used to inform the front seat occupants of the passenger air bag deactivation state. The PAD indicator is a stand-alone lamp installed into the vehicle instrument panel in a position visible to each front seat occupant.
The restraints control module (RCM) controls the state of the PAD indicator through a direct hardwire connection, based on information provided by the occupant classification sensor (OCS) system. The PAD indicator is lit to indicate the passenger air bag module is disabled. An exemption to this is when the front passenger seat is determined to be empty and passenger safety belt buckle unbuckled, and therefore indication of a deactivated passenger air bag module is not necessary. In all other cases, the PAD indicator is unlit when the passenger air bag module is enabled.
When the ignition switch is in the ON position, the PAD indicator prove-out period is initiated by the RCM. The RCM briefly activates the PAD indicator to prove-out the indicator function and verify to the front occupants correct functional operation of the PAD indicator.
The PAD indicator will be lit/unlit within 1.0 to 1.5 seconds of a change of state from the OCS system.
When an OCS system fault is present, the RCM defaults the passenger air bag module to the last valid state received from the OCS system until the ignition switch is turned OFF. If the OCS system fault is still present when the ignition switch is turned ON, the RCM defaults the passenger air bag module to enabled regardless of the size of occupant in the front passenger seat. The PAD indicator will be unlit. For information on the OCS system, refer to Occupant Classification Sensor System in this section.
The following table indicates the passenger air bag status and the PAD indicator status based the size of the front outboard passenger occupant.

srs lights are the airbag light most common fault is a wire in the steering which atatches to air bag on steering wheel cannot remember what its called but i have just replaced mine for same problem

If you are talking about the SRS light, the LFC ( light Flash Code ) 27 is :

Passenger Air Bag Deactivation ( PAD ) warning lamp shorted to ground

Have you done, or had any work done in the dash area as of late ?

The PAD light cannot illuminate, so the truck is reporting the code via the SRS LFC.

Start with the PAD lamp, and work you way backwards on the wiring harness, looking for a wire that has the insulation damaged, and making contact with the dash frame.
Could be right at the PAD lamp holder also.

This will take some time, but should be an easy fix.

Your SRS light is related to your "airbag system". You need to have it repaired because you have no airbags while that light is on.

Well thats one of two things. First the srs light stands for Supplemental Restraint System or in otherwords the airbag system now the light being on could be because its due for a maintance check up or there could be a problem with the system

Hi, Joe here to help,
Without going to a dealer, you need to get a scan tool to reset the srs light. Go to an Autozone store, They will scan it and reset it free of charge.

Passenger Air Bag Deactivation (PAD) Switch
The passenger air bag deactivation (PAD) switch:

• is located on the instrument panel to the right of the climate controls.
• contains a light emitting diode (LED) that indicates when the PAD switch is activated (passenger air bag disabled).
• allows the passenger air bag deployment circuit to be disabled using the ignition key.
• should be used whenever a child safety seat is being used in the front passenger seating position.

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Prove Out the System
Prove out the system means to turn the ignition switch from the OFF to the RUN position and visually monitor the air bag indicator with the air bag modules installed. The air bag indicator will light continuously for approximately six seconds and then turn off. If an air bag supplemental restraint system (SRS) fault is present, the air bag indicator will either:

• fail to light.
• remain lit continuously.
• flash.

The flashing might not occur until approximately 30 seconds after the ignition switch has been turned from the OFF to the RUN position. This is the time required for the restraints control module (RCM) to complete the testing of the SRS. If the air bag indicator is inoperative and an SRS fault exists, a chime will sound in a pattern of five sets of five tone bursts. If this occurs, the air bag indicator will need to be repaired before diagnosis can continue.
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Active Commands
This command allows the technician to verify operation of the air bag indicator, passenger air bag deactivation (PAD) lamp and chime. When the air bag output command is executed, the indicator, the PAD lamp, chime and the chime are activated simultaneously for approximately four seconds. All devices are deactivated automatically.

you need to have the airbag system checked...srs stands for supplemental restraint system....as long as that light is o the airbag may or may not work or may go off when it shouldnt

We had the seat pan replaced on the passenger side because the SRS indication came on. My wife put her knee right in the middle of the seat, probably breaking the sensor, while assisting the kids in the back seat.