Check quiescent current consumption - AR54.10-P-1030RT

MODEL 251

	Risk of explosion caused by escaping oxyhydrogen gas. Risk of injury caused by caustic burns to eyes, skin and mucous membranes from battery electrolyte (contains diluted sulfuric acid) or metal spatter due to short circuit. Risk of burn injuries caused by short circuit. Risk of poisoning caused by swallowing battery electrolyte (contains diluted sulfuric acid) or absorption of lead over the skin or orifices	No fire, sparks, open flames or smoking. Wear acid-resistant gloves and clothing and safety glasses with side guards. Do not place any conductive objects on the battery and avoid any short circuit from battery positive to ground. Only fill liquid battery electrolyte (diluted sulfuric acid) into suitable and appropriately marked containers.	AS54.10-Z-0001-01A
	Notes on battery	All models	AH54.10-P-0001-01A
	Notes on AGM battery		AH54.10-P-0002-01A
	Removing
1	Switch of all electrical and electronic equipment, remove additional consumers (e.g. adaptors connected to 12 V-power outlets), switch off ignition and detach the transmitter key from the EIS [EZS] control unit	On vehicles with Keyless Go, code 889: Press Keyless Go start/stop button repeatedly until ignition is switched off. Remove transmitter key from vehicle and store it in a location beyond its transmission range (at least 2 m).
2	Expose the battery negative terminal and battery compartment prefuse box	Do not disconnect the ground line, do not remove the battery. See: ↓
2		Remove/install battery	AR54.10-P-0005RT
3.1	Connect positive measurement cable of multimeter to ground connection of body	When measuring with multimeter.
3.1		Electrical connection set Multimeter	Fig 1
4.1	Loosen the nut on the terminal of the battery negative pole, pull the terminal of the battery negative pole carefully upwards and simultaneously connect the negative measuring cable of the multimeter to the battery negative pole	When measuring with multimeter. The circuit should not be broken as this could delete faults that may be stored in the control units. If the multimeter cannot be attached without breaking the circuit, an additional battery must be connected parallel to the power supply battery. The multimeter can now be looped in free from interruptions between the battery negative pole and ground connection. Once the multimeter has been looped in the additional battery must be disconnected again.
4.1		Electrical connection set Multimeter	Fig 1
5.1	Completely detach battery negative pole terminal from battery negative pole	When measuring with multimeter.
6	Open engine hood, trunk lid and all doors, position the rotary tumblers in the locks of the engine hood, of the trunk lid and doors on the "closed" position	Once the measurement is finished the rotary tumblers must be unlocked again by actuating the external handles or the engine hood release as otherwise they may be destroyed when closing. The engine hood, trunk lid and doors are opened in order to guarantee the access to all fuse boxes, fuse and relay boxes and bus nodes. After placing the rotary tumblers in the "closed" position, the interior light is switched off after a delay of approx. 10 s.
7	Locking the vehicle from outside with the remote control	On vehicles with Keyless Go, code 889: Remove transmitter key from the vehicle and store outside the transmission range (at least 2 m). It must be ensured that a jump-starting device is not connected to the vehicle. The time between locking the vehicle and performing the measurements must be at least 35 minutes. The vehicle must be stationary during this time. No doors should be opened or closed, the vehicle should not be locked and unlocked, and none of the switches and instruments should be operated.
	Measure
8	Check quiescent current consumption	A measured value of 50 mA must not be exceeded. Possible causes for increased values: ↓ If the measured value is between 0.05 and 1.6 A, this usually indicates that a control unit has failed to switch itself off. However, this can also be caused by an electric or electronic component (e.g. switch or relay). At a value over 1.6 A as a rule a defective control unit keeps the engine CAN bus (CAN-C), the interior CAN bus (CAN-B) or the telematics CAN alert. Measurement with multimeter: ↓
8	Check quiescent current consumption	Electrical connection set Multimeter When measuring with current clamp: ↓ Current measurement pliers Current clamp with display and multimeter connection for checking quiescent current Current clamp with multimeter connection for checking quiescent current Current clamp with display for quiescent current measurement	Fig 1
9.1	Locate defective consumers via power supply	With a quiescent current consumption between 0.05 and 1.6 A (after a waiting time of at least 35 min after locking). For wiring diagram information on the front prefuse box, see	AR54.10-P-1030-09RT
	Fuse assignment of front prefuse box		GF54.15-P-1256-07RT
	Wiring diagram of front backup fuse box (F32]		PE54.15-P-2502RAA
		Wiring diagram information on the battery compartment prefuse box.
	Fuse assignment of battery compartment prefuse box		GF54.15-P-1256-15RT
	Wiring diagram for battery compartment prefuse box (F33)		PE54.15-P-2508RAA
		Wiring diagram information on the engine compartment fuse and relay box, right.
	Fuse assignment of fuse and relay box in right engine compartment		GF54.15-P-1256-02RT
	Relay assignment of fuse and relay box in right engine compartment		GF54.15-P-1257-02RT
	Wiring diagram for front fuse and relay box	Fuse and relay box F58, specification 1	PE54.15-P-2107RAA
		Fuse and relay box F58, specification 2 Wiring diagram information on cockpit fuse box.	PE54.15-P-2107RAB
	Fuse assignment of fuse box in cockpit		GF54.15-P-1256-16RT
	Wiring diagram for cockpit fuse box (F3)		PE54.15-P-2901RAA
		Wiring diagram information on rear fuse and relay box.
	Fuse assignment of load compartment fuse and relay box		GF54.15-P-1256-14RT
	Relay assignment of the load compartment fuse and relay box		GF54.15-P-1257-08RT
	Rear fuse and relay box wiring diagram	Fuse and relay box F4, specification 1	PE54.15-P-2103RAA
		Fuse and relay box F4, specification 2	PE54.15-P-2103RAB
		Fuse and relay box F4, specification 3	PE54.15-P-2103RAC
9.2	Locate defective consumer via CAN bus	With a quiescent current consumption >1.6 A (after a waiting time of at least 35 min after locking). Multimeter Wiring diagram information on interior CAN bus (CAN-B).	AR54.10-P-1030-10RT
	Location and assignment of line and plug connectors, cockpit		GF00.19-P-1000-03RAA
	Wiring diagram for interior CAN bus	Voltage distributor X30/4 and X30/6, specification 1	PE00.19-P-2300RAA
		Voltage distributor X30/7, specification 2 Wiring diagram information on engine CAN bus (CAN-C).	PE00.19-P-2300RAB
	Location and assignment of line and plug connectors, cockpit		GF00.19-P-1000-03RAA
	Wiring diagram for engine CAN bus		PE00.19-P-2200RAA
		Wiring diagram information on CAN Bus telematics (telematics CAN).
	Location and assignment of line and plug connectors, interior compartment, left	Only on vehicles with rear entertainment system, code 864 and/or with rear audio system, code 519.	GF00.19-P-1000-04RAA
	Wiring diagram for telematics CAN bus	Only on vehicles with rear entertainment system, code 864 and/or with rear audio system, code 519.	PE82.00-P-2720RAA
10.1	Disconnect the negative measuring cable from the battery negative pole, simultaneously connect the terminal for the battery negative pole completely to the battery negative pole and tighten the nut on the terminal for the battery negative pole	During the measurement with the multimeter.
10.1		The circuit must not be interrupted.	*BA54.10-P-1012-01C
	Remove/install
11	Remove consumer identified as being defective and fit new consumer	Subject to a new order.
12	Read out and erase fault memory	STAR DIAGNOSIS diagnosis system
	Connect STAR DIAGNOSIS and read out fault memory	STAR DIAGNOSIS diagnosis system	AD00.00-P-2000-04A
	Measure
13.1	Recheck quiescent current consumption	When electrical/electronic equipment have been replaced or removed and installed.
	Install
14	Reinstall cover parts of the battery and battery compartment	See: ↓
14		Remove/install battery	AR54.10-P-0005RT
15.1	Reinstall all parts which have been removed	If parts have been removed in order to permit access to fuse boxes, fuse and relay boxes, bus nodes and electrical/electronic components.
16	Move the rotary tumblers of the engine hood catches, the trunk lid and all doors by actuating the external handles or the engine hood release in the "open" position, close engine hood, trunk lid and all doors	The rotary tumblers must be unlocked again as otherwise they may be destroyed when closing.

BATTERY

Number	Designation			Model 251
BA54.10-P-1012-01C	Nut, battery cable to battery terminal	M6	Nm	6

Fig 1: Identifying Electrical Connection Kit (220 589 00 99 00)

Courtesy of MERCEDES-BENZ USA