Cylinder Head Coolant Valve - N489-, Checking

General Description

The rotary coolant valve (RCV) module combines several elements (thermostat, valves, coolant pump, etc.) into one component. Two mechanically connected RCVs are part of the module. The position of RCV 1 controls the coolant flow through the engine oil cooler, the cylinder head and the main radiator. The RCV 2 controls the coolant flow through the cylinder block. The engine temperature can be adjusted to an optimum value regarding engine speed and load. In addition, the engine heat-up to optimum operating temperature is accelerated by the fact that the coolant circulation can be minimized. A position sensor detects the position of RCV 1. The monitor detects a stuck RCV. An emergency thermostat opens the main cooling circuit if the engine temperature is too high.

Special Tools And Workshop Equipment Required

Multimeter.
Wiring Diagram.
Scan Tool.

Test Requirements

Fuses OK.
Battery voltage OK.
Switch OFF all electrical and electronic accessories.
Vehicles with automatic transmission, ensure the selector lever position is in "P".
Vehicles with manual transmission, ensure the shifter lever position is in "N" with the parking brake applied.
Observe all safety precautions: SAFETY PRECAUTIONS .
View clean working conditions: CLEAN WORKING CONDITIONS .

Test Procedure

Step	Procedure	Result / Action to Take
1	PERFORM: Preliminary Check to verify the customers complaint. Refer to PRELIMINARY CHECK . -- Was Complaint verified?	-- YES: GO TO: Step 2 Cylinder Head Coolant Valve - N489-, CHECKING - 2 . -- NO: GATHER more information from customer about the complaint.
2	IGNITION: OFF. DISCONNECT: Cylinder Head Coolant Valve -N489- harness connector. CHECK: Cylinder Head Coolant Valve -N489- component connector terminals 1 to 2 for resistance. SPECIFIED VALUE: 20 - 90 Ω (@ approx. 20° C). -- Was Value obtained?	-- YES: GO TO: Step 3 Cylinder Head Coolant Valve - N489-, CHECKING - 3 . -- NO: REPLACE: Cylinder Head Coolant Valve -N489-. Refer to the appropriate service information. GO TO: Step 5 Cylinder Head Coolant Valve - N489-, CHECKING - 5 .
3	IGNITION: ON. CHECK: Cylinder Head Coolant Valve -N489- harness connector terminal 1 to ground for voltage. SPECIFIED VALUE: Battery voltage. IGNITION: OFF. -- Was Value obtained?	-- YES: GO TO: Step 4 Cylinder Head Coolant Valve - N489-, CHECKING - 4 . -- NO: PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 5 Cylinder Head Coolant Valve - N489-, CHECKING - 5 .
4	REMOVE: Engine Control Module - J623-. Refer to the appropriate service information. CHECK: Cylinder Head Coolant Valve -N489- harness connector terminal 2 to the Engine Control Module - J623- harness connector T94 / 29 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Was Value obtained?	-- YES: TIP: The Cylinder Head Coolant Valve -N489- may fail under loaded operation; please swap a known good Cylinder Head Coolant Valve -N489- prior to continuing to the next step. GO TO: Step 5 Cylinder Head Coolant Valve - N489-, CHECKING - 5 . -- NO: PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 5 Cylinder Head Coolant Valve - N489-, CHECKING - 5 .
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