Function of electrical coolant level indicator - RA20001044450X(20-4450)

Model 124 

Fig 1: Function Of Electrical Coolant Level Indicator (Model 124)

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

General 

The coolant level indicator monitors the coolant level in the expansion reservoir (1) when the engine is running.

When the ignition is switched on, the warning light (A1e11) comes on weakly (check function) and goes out if the coolant is at the correct level as soon as the engine is started.

The coolant level sensor (S41) has two retaining lugs of different width and can only be installed in one position. It is sealed by means of an O-ring (52) and is fixed in place by a circlip (55).

Operation 

If the coolant is at the correct level, a permanent magnet (2) in the float (51) and a permanent magnet (3) in the sensor (S41) keep a contact (arrow) open.

If the coolant level is too low, the float (51) moves down and the permanent magnet (3) closes the contact (arrow) in the coolant level sensor (S41). A permanent input signal (vehicle ground) exists at the microprocessor (a) in the electrical base plate of the instrument panel unit (A1) and the warning lamp (A1e11) comes on with a bright light.

Models 129, 140, 202, 210 

Fig 2: Function Of Electrical Coolant Level Indicator (Models 129, 140, 202, 210)

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

General 

In models 129, 140, 202, 210, coolant does not flow directly around the coolant level sensor (S41) and the sensor can be removed and installed without draining the coolant in the expansion reservoir (1).

Operation 

If the coolant level is too low, the ring magnet (54) in the float (1) closes the contact (arrow) in the coolant level sensor (S41).

A permanent input signal (vehicle ground) exists at microprocessor (a) in the electrical base plate of the instrument panel unit (A1) and the warning light (A1e11) comes on with a bright light.