Test coolant thermostat - AR20.10-P-2455GZA (ML350, ML550, GL450, GL550)

WARNING: This page does not describe the selected car, but rather 28 other vehicles, including the 2012 Mercedes-Benz GL550, 2012 Mercedes-Benz GL450, 2011 Mercedes-Benz ML63, 2011 Mercedes-Benz ML550, and 2011 Mercedes-Benz ML350. However, it is still accessible from the selected car via links, so may be relevant.

ENGINE 272, 273 in MODEL 164, 251

Shown on engine 272

Fig 1: Identifying Multimeter, Electrical Connector And Three-Disk Thermostat Valve

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

	Remove/install
	Information on preventing damage to electronic components due to electrostatic discharge		AH54.00-P-0001-01A
1	Switch off ignition and remove the transmitter key from the EIS [EZS] control unit	On vehicles with code (889) Keyless Go: 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	Remove poly-V belt		AR13.20-P-0001GZA
3	Disconnect electrical connector (4) at three disc thermostat valve (Y110)
	Check
4	Connect multimeter (3) with adapter cable (1) to three disc thermostat valve (Y110)		Fig 2
5	Measure resistance	If resistance does not comply with preset data, the three disc thermostat valve (Y110) must be replaced: ↓
		Remove coolant thermostat	AR20.10-P-2460GZA
		Resistor	*BE20.10-P-1003-02C
6	Install in the reverse order
7	Connect STAR DIAGNOSIS and read fault memory	Stored faults which may be caused by disconnecting cables or by simulation during test operations, must be erased in the fault memory after completing the work.	AD00.00-P-2000-04A

CHECK VALUES FOR COOLANT THERMOSTAT

Number	Designation			Engine 272	Engine 273
BE20.10-P-1003-02C	Resistor	at 20°C	Ω	15.2 (± 1.5)	15.2 (± 1.5)

Fig 2: Identifying Electrical Connection Kit (220 589 00 99 00)

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.