Checking Cooling System

Checking the cooling system

Checking the cooling system
The cooling system has several different functions. The engine control module (ECM) is an interlinking control module to control the engine motor fan, but also the diagnostics for the complete cooling system.
The component parts of the cooling system are:
- Engine cooling fan/ Control module Engine cooling fan
- A/C pressure sensor.
- Engine coolant temperature (ECT) sensor.
The engine cooling fan has two functions. One is to cool the engine compartment and the other is to cool the condenser when the A/C compressor is running.
The engine control module (ECM) sends a pulse width modulated (PWM) signal to the engine cooling fan's control modules, which in turn send a pulse width modulated (PWM) signal to activate the fans at different speeds. The speed is determined by the engine control module (ECM) and is dependent on the temperature of the coolant and the speed of the vehicle.
The temperature conditions for connection of the engine motor fan's different steps can vary slightly depending on the engine variant and equipment. Temperature conditions apply to:
- With the A/C shut off.
- When no fault is detected by the engine control module (ECM).
A cooling system fault can result in a lack of cooling of the engine or A/C. The engine control module (ECM) commands continuous activation of the engine cooling fan if there are active diagnostic trouble codes for any of the component parts of the cooling system, which result in component failure.
The reason that the engine cooling fan is activated continuously is that:
- Serious damage to the engine must be avoided.
- The A/C system must maintain its functionality.
The symptoms that can occur are:
- Engine cooling/Engine cooling fan (FC) always activated
- Engine cooling fan (FC)/Unusual noise





Continue - Fault tracing according to active DTCs.

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Fault tracing according to active DTCs.
Check for active DTCs for any of the following components:
1. Engine cooling fan/ Control module Engine cooling fan
2. A/C pressure sensor.
3. Engine coolant temperature (ECT) sensor.
If there are any active DTCs, fault trace and remedy as necessary according to the relevant DTC's fault tracing.

Continue - Checking the connections to the A/C pressure sensor

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Checking the connections to the A/C pressure sensor
Diagnostics have not detected a problem with the A/C pressure sensor ground lead. This signifies that the A/C pressure sensor's ground lead can be defective despite there being no active diagnostic trouble codes on the engine control module (ECM).
Check the ground lead between the A/C pressure sensor and the engine control module (ECM) with regard to an open circuit and short circuit.

Note! The cables between the Engine control module (ECM) and connector for the air conditioning (A/C) pressure sensor may be routed via a clamp where contact resistance/oxidation or other defects can occur.For further information see the wiring diagram.

Check the connector for the air conditioning (A/C) pressure sensor. Check for loose connections and/or contact resistance/oxidation.









Was a fault detected?

Yes - FAULT FOUND

No - Attempt New Test

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