Front seats - Revision history

Pokseva: /* Installing seat occupancy sensor emulator */ added note on type 2 emulator for facelift W220

2025-12-20T17:15:27Z

Installing seat occupancy sensor emulator: added note on type 2 emulator for facelift W220

← Older revision		Revision as of 17:15, 20 December 2025
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	===Installing seat occupancy sensor emulator===		===Installing seat occupancy sensor emulator===
	An electronic emulator may be purchased on eBay for a few dollars and substituted for the SRS Sensor Mat. Search for something like "seat ~~occupancy~~ sensor ~~w220~~" (~EUR 5).		An electronic emulator may be purchased on eBay for a few dollars and substituted for the SRS Sensor Mat. Search for something like "seat occupation sensor emulator W220" (~EUR 10).

			There are two types of sensors available depending on W220 model year:
			* Type 6 for pre-[[facelift]] W220
			* Type 2 for [[facelift]] W220

	'''Safety note:''' The emulator simulates that there is always someone sitting in the passenger seat, so in case of an accident, the airbag goes on.		'''Safety note:''' The emulator simulates that there is always someone sitting in the passenger seat, so in case of an accident, the airbag goes on.
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	{\|		{\|
	\|[[File:W220 SRS Emulator 001.JPG\|thumb\|none\|~~SRS occupancy~~ sensor emulator]]		\|[[File:W220 SRS Emulator 001.JPG\|thumb\|none\|Seat occupation sensor emulator (Type 6)]]
	\|[[File:W220 SRS Emulator 002.JPG\|thumb\|none\|Internal view of the emulator]]		\|[[File:W220 SRS Emulator 002.JPG\|thumb\|none\|Internal view of the emulator]]
			\|[[File:W220_seat_occupation_sensor_emulator_type_2.jpg\|thumb\|none\|Seat occupation sensor emulator (Type 2)]]
	\|}		\|}

Pokseva: /* Remove/install front seat (as of 01/09/2002) */ photos of retaining clam at bowden cable added

2018-06-30T20:50:50Z

Remove/install front seat (as of 01/09/2002): photos of retaining clam at bowden cable added

@@ Line 1,526: / Line 1,526: @@
 * Bolt to seat runner: 45 Nm
 * Screw on belt end fitting: 30 Nm
 {|

Pokseva: /* Front passenger seat occupied and child seat recognition sensor (B48) */ notes on fixing the sensor

2018-06-30T20:39:41Z

Front passenger seat occupied and child seat recognition sensor (B48): notes on fixing the sensor

← Older revision		Revision as of 20:39, 30 June 2018
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	==Front passenger seat occupied and child seat recognition sensor (B48)==		==Front passenger seat occupied and child seat recognition sensor (B48)==

	~~If the SRS Indicator and Warning Lamp stays on or comes on intermittently a possible cause is that the Passenger~~ Seat ~~Weight Sensor~~ (~~Front passenger seat occupied and child seat recognition~~ sensor (~~B48~~)~~), commonly called the SRS Sensor Mat, is faulty or failing.~~		{\|
			\|[[File:W220_Front_Seat_Occupant_Sensor_A2208211681.jpg\|thumb\|none\|Seat occupant sensor (A2208211681)]]
			\|[[File:W220_Front_Seat_Occupant_Sensor_module_A2208211681.jpg\|thumb\|none\|Occupant sensor module (A2208211681)]]
			\|}

	~~Weight sensor costs around EUR 250. It's not just~~ the ~~sensor, you have to replace~~ the seat ~~bottom actually~~ (~~pull the existing one out, pull it out of the leather, put new one in, and plug in / put back together. The SDS can be used to test the connection to see if the seat~~ is ~~empty~~ or ~~occupied; it should set off as occupied after 26 lbs" (12Kg)~~.		If the SRS indicator and warning lamp stays on or comes on intermittently a possible cause is that the passenger seat occupancy sensor (also known as weight sensor or SRS sensor mat) is faulty or failing.

	~~There are three options to fix the SRS Indicator and Warning Lamp staying on.~~		{\| class="wikitable"
	~~# Replace the~~ Front passenger seat occupied and child seat recognition ~~sensor (B48~~).		! Error Code
	~~# Dismantle the Passenger Seat (be warned this is a substantial task) and diagnose where the issue~~ is ~~occurring. If you are lucky and it is in the electrical cable between the plug connector and the Sensor Mat then it can be repaired.~~		! Generated By
	~~# Replace the SRS Sensor Mat with an electronic emulator~~.		! Description
	~~# Disable the passenger seat occupation sensor in SDS.~~		\|-
			\|9028
			\|AB - Airbag
			\|The coding for component B48 (Front passenger seat occupied and child seat recognition) is faulty.
			\|}

	===Disabling seat occupancy sensor in ~~SDS~~===		There are four options to fix the SRS indicator and warning lamp staying on:
	To disable passenger seat occupancy sensor in ~~SDS~~ select control unit "AB - Airbag" -> "Development data" -> "Control unit adaptations" -> "Control unit adaptations (Variant coding)" -> "Fahrzeugausstattung kodieren" and change "AKSE/OC Beifahrer" from "ja" to "nein" (see photo below).		# Replace the front passenger seat occupied and child seat recognition sensor (B48). The sensor costs around EUR 480 and its replacement involves dissecting seat cushion (be warned this is a substantial task). The DAS can be used to test the connection to see if the seat is empty or occupied; it should set off as occupied after 26 lbs" (12Kg).
			# Diagnose where the issue is occurring and fix the sensor (see below).
			# Disable the passenger seat occupancy sensor in DAS (see section below).
			# Replace the sensor with an electronic sensor emulator (see section below).

			=== Fixing seat occupancy sensor ===
			If the Airbag ECU says it can't communicate with the seat occupancy sensor, or open or shorted wiring, then any one of these causes may exist:
			* Breakage of electrical cable between the plug connector and the sensor (quite common). If this is the case the wire can be repaired.
			* The sensor elements may be dead
			* The sensor electronics may be shorted. This can be quickly verified by measuring the voltage between the red and brown wires in the yellow connector, the voltage should be about 12V DC. The sensor mat gets the power from the seat control module located under the passenger seat. If it is around 0.6V, the sensor is short-circuiting the supply voltage to the ground which causes the built-in circuit protection to drop the voltage to 0.6V when the sensor is connected. The electronics are in the white box inside the seat cushion. The white box is filled with some caulk type filler. Nasty job, this box is neither meant to be opened nor repaired. Once opened and the caulk excavated (using knives, screw drivers and a heat gun) to reveal the components, there can be found a 15uF tantalum capacitor which is shorted when voltage is applied to it. It can be replaced with a regular electrolytic capacitor.

			===Disabling seat occupancy sensor in DAS===
			To disable passenger seat occupancy sensor in DAS select control unit "AB - Airbag" -> "Development data" -> "Control unit adaptations" -> "Control unit adaptations (Variant coding)" -> "Fahrzeugausstattung kodieren" and change "AKSE/OC Beifahrer" from "ja" to "nein" (see photo below).

	[[File:W220_DAS_disable_passenger_occupancy_sensor.png\|thumb\|none\|DAS: Passenger seat occupancy sensor enabled]]		[[File:W220_DAS_disable_passenger_occupancy_sensor.png\|thumb\|none\|DAS: Passenger seat occupancy sensor enabled]]

Pokseva: /* Remove/install front seat backrest (as of 01/09/2002) */ note about interchangeability

2018-06-30T20:05:32Z

Remove/install front seat backrest (as of 01/09/2002): note about interchangeability

← Older revision		Revision as of 20:05, 30 June 2018
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	Torque specifications:		Torque specifications:
	* Bolt on backrest fitting: 35 Nm		* Bolt on backrest fitting: 35 Nm

			Seat backrest leather cover is interchangeable between left and right seat.
			Backrest seat-back lining is interchangeable between left and right seat.
			Seat backrest frame has different code in EPC depending on the left or right seat, however, backrest rest has the same code and thus is interchangeable.

	{\|		{\|

Pokseva: /* Remove/install front seat backrest seat-back lining */

2018-06-30T20:01:49Z

Remove/install front seat backrest seat-back lining

← Older revision		Revision as of 20:01, 30 June 2018
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	# Install in the reverse order		# Install in the reverse order

			Backrest seat-back lining is interchangeable between left and right seat backrest.
	{\|		{\|
	\|[[File:W220_seat_backrest_lining_screw.jpg\|thumb\|none\|Seat backrest lining screw.]]		\|[[File:W220_seat_backrest_lining_screw.jpg\|thumb\|none\|Seat backrest lining screw.]]

Pokseva: /* Remove/install front seat cushion (as of 01/09/2002) */ note about left/right interchangeability

2018-06-30T19:56:54Z

Remove/install front seat cushion (as of 01/09/2002): note about left/right interchangeability

← Older revision		Revision as of 19:56, 30 June 2018
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	* Bolt, seat cushion to seat adjustment mechanism: 15 Nm		* Bolt, seat cushion to seat adjustment mechanism: 15 Nm

	~~The leather on seat~~ cushion is interchangeable between left and right seat cushion ~~(not known about~~ the ~~whole cushion)~~.		Seat cushion frame is interchangeable between left and right seat cushion.
			The cushion rest and cushion leather cover, however, have different part numbers in EPC depending on the side.
	Passenger seat cushion has passenger occupancy sensor installed with extra connector (yellow).		Passenger seat cushion has passenger occupancy sensor installed with extra connector (yellow).

Pokseva: photos from EPC added

2018-06-30T19:53:22Z

photos from EPC added

← Older revision		Revision as of 19:53, 30 June 2018
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			[[File:W220_prefacelift_front_seat_crosscut.jpg\|thumb\|none\|Pre-[[facelift]] front seat (crosscut).]]

	[[File:~~W220_prefacelift_front_seat_crosscut~~.~~jpg~~\|thumb\|none\|~~Pre-~~[[~~facelift~~]] ~~front~~ seat ~~(crosscut)~~.]]		{\|
			\|[[File:W220_DAS_EPC_drivers_seat_1.png\|thumb\|none\|EPC: Driver's seat: left seat]]
			\|[[File:W220_DAS_EPC_drivers_seat_2.png\|thumb\|none\|EPC: Driver's seat: left seat]]
			\|[[File:W220_DAS_EPC_drivers_seat_3.png\|thumb\|none\|EPC: Driver's seat: right seat]]
			\|[[File:W220_DAS_EPC_drivers_seat_4.png\|thumb\|none\|EPC: Driver's seat: right seat]]
			\|}
			{\|
			\|[[File:W220_DAS_EPC_drivers_seat_5.png\|thumb\|none\|EPC: Driver's seat: seat adjustment]]
			\|[[File:W220_DAS_EPC_drivers_seat_6.png\|thumb\|none\|EPC: Driver's seat: coverings, fire extinguisher, first aid box]]
			\|[[File:W220_DAS_EPC_drivers_seat_7.png\|thumb\|none\|EPC: Driver's seat: Front seat safety belt]]
			\|}

	== Front seat adjustment ==		== Front seat adjustment ==

Pokseva: /* Remove/install front seat backrest frame overpressure reservoir */ photo added

2018-06-30T13:47:15Z

Remove/install front seat backrest frame overpressure reservoir: photo added

← Older revision		Revision as of 13:47, 30 June 2018
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	# Install in the reverse order		# Install in the reverse order
	# Perform function check of lumbar support or multicontour backrest		# Perform function check of lumbar support or multicontour backrest

			[[File:W220_front_seat_overpressure_reservoir.jpg\|thumb\|none\|Front seat overpressure reservoir]]

	==Remove/install front seat backrest lumbar support air cushion (except code 404/405/433/434)==		==Remove/install front seat backrest lumbar support air cushion (except code 404/405/433/434)==

Pokseva: /* Remove/install front seat cushion (as of 01/09/2002) */ photos added

2018-06-30T13:45:37Z

Remove/install front seat cushion (as of 01/09/2002): photos added

@@ Line 1,771: / Line 1,771: @@
 Torque specifications:
 * Bolt, seat cushion to seat adjustment mechanism: 15 Nm
 ==Remove/install front seat cushion covering (up to 31/08/2002)==

Pokseva: /* Remove/install front seat control module (as of 01/07/2001) */ photo added

2018-06-30T13:35:26Z

Remove/install front seat control module (as of 01/07/2001): photo added

← Older revision		Revision as of 13:35, 30 June 2018
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	# Install in the reverse order		# Install in the reverse order
	# Perform front seat adjustment function test		# Perform front seat adjustment function test

			[[File:W220_drivers_left_front_seat_control_module.jpg\|thumb\|none\|Left front seat control module (A2208205585)]]

	==Remove/install front seat adjustment mechanism==		==Remove/install front seat adjustment mechanism==