3315697 - E5020 ENGINE COOLING - Functional description

Functional description

The power supply to both fans N11 and N12 is controlled by two relays R7 (1. speed) and R6 (2. speed), located in relay control unit B3 . Both relays are supplied with power directly from the battery - junction unit A5 - by a line protected by a special fuse F9 for R7 and F8 for R6 , all located in B3 .

Functional description

These are excited by an earth signal from 4-stage pressure switch K10 and engine management unit M10;

• if the coolant temperature reaches the first temperature stage, or the 4-stage pressure switch K10 pin 3 - indicates to control unit M10 pin 15 of connector E - that the first pressure stage has been reached, control unit M10 sends a signal to 1st speed relay R7 from pin 6 of connector A.
• if the engine coolant reaches a higher temperature level, or the 4-stage pressure switch K10 pin 6 - indicates to control unit M10 pin 17 of connector E - that a higher pressure level has been reached, control unit M10 sends an earth signal to 2nd speed relay R6 from pin 3 of connector D.