Radiator Cooling Fan: Testing and Inspection
Electric coolant fan, checking
Special tools, testers and auxiliary items required
^ Hand multimeter V.A.G 1526 B or V.A.G 1526 A
^ Voltage tester V.A.G 1527 B
^ Connector test kit V.A.G 1594 C or V.A.G 1594 A
^ Test box V.A.G 1598/31
^ Vehicle Diagnostic, Testing and Information System VAS 5051 with diagnostic cable VAS 5051/1
Work sequence
- Connect Vehicle Diagnostic, Testing and Information System VAS 5051 A and select vehicle system "01 - engine electronics". For this, ignition must be switched on Guided Fault Finding in VAS 5051.
Display on VAS 5051:
- In selection - 1 -, click on the function "03 - output Diagnostic Test Mode (DTM)"
- Press - button repeatedly, until "coolant fan activation 2" is activated.
^ Coolant Fan Control (FC) Control Module 2 J671 switches on Coolant Fan 2 V177 (right) 1 time slowly to full speed.
- Press -> button repeatedly, until "coolant fan activation 1" is activated.
^ Coolant Fan Control (FC) Control Module J293 switches on Coolant Fan V7 (left) 1 time slowly to full speed.
- End function "03 - output Diagnostic Test Mode (DTM)" by pressing <- button.
If fan activation does not react as described:
- Produce conditions for starting up coolant fan according to required input criteria (e.g. switch on A/C system, increase engine temperature correspondingly).
Display on VAS 5051:
- In selection - 1 -, click on function "08 - Read measuring value block".
Display on VAS 5051:
1 - Enter display group
- Select function "135" in button field - 2 - for "display group 135" and press Q to confirm input.
Display on VAS 5051:
- Check indication in display fields - 2 - and - 3 -.
Note:
^ At fan request by A/C system and/or coolant temperature greater than 98° C, duty cycle must rise above 10% and fans must start up.
- Press <- button to end function "08 - Read measuring value block".
If duty cycle does not rise above 10%:
- Read out DTC memory of engine control module (ECM).
- Select "06 - End Output".
- Switch off ignition.
- Repair displayed malfunctions if necessary.
If respective fan does not start up even though duty cycle is above 10%:
- Check Coolant Fan V7 or Coolant Fan 2 V177.
Checking Coolant Fan V7 (left)
^ Fuses for Coolant Fan V7 and Coolant Fan Control (FC) Control Module J293 OK.
- Remove cover - 1 - in engine compartment (left side).
- Remove electrical harness connector - 1 - from bracket and disconnect it.
- Connect multimeter for voltage measurement as follows.
^ Specification: approximately battery voltage respectively
If specifications are not obtained:
- Repair wire connection if necessary.
If specified values are achieved:
- Connect multimeter for voltage measurement as follows:
^ Specification: approximately battery voltage
If specification is not obtained:
- Repair wire connection if necessary.
If specified value is not achieved:
- Connect multimeter between terminal - 2 - and - 3 - of harness connector for voltage measurement.
^ Vehicle Diagnostic, Testing and Information System VAS 5051 connected, "Vehicle Self-Diagnosis" and vehicle system "01 Engine electronics" selected. The ignition must be switched on.
Display on VAS 5051:
- In selection - 1 -, click on function "03 - output Diagnostic Test Mode (DTM)"
- Press - key repeatedly, until "coolant fan activation 1 " is activated.
^ Voltage value must decrease slowly from approximately battery voltage to approximately 8 volts (and then increase again).
- End function "03 - output Diagnostic Test Mode (DTM)" by pressing - button.
- Select "06 - End Output"
- Switch off ignition.
If specification is not obtained:
- Connect test box V.A.G 1598/31 to wiring harness connectors, Engine Control Module (ECM) is not connected. Connect Ground (GND) clip at test box (not visible in illustration) to Ground (GND).
CAUTION! To avoid damaging electronic components, set measuring range before connecting test leads and observe all test requirements.
- Check following wire connection for open circuit and short circuit to Ground (GND) and B+:
- Repair wire connection if necessary.
If no malfunctions are detected:
- Remove front bumper cover.
- Connect multimeter with measuring probes and connector adapters from connector test kit VAG 1594 C between terminal - 1 - and terminal - 2 - of brown harness connector on Coolant Fan Control (FC) Control Module J293 ; harness connector remains connected.
^ Vehicle Diagnostic, Testing and Information System VAS 5051 A connected, "Vehicle Self-Diagnosis" and vehicle system "01 Engine electronics" selected. The ignition must be switched on.
Display on VAS 5051:
- In selection - 1 -, click on function "03 - output Diagnostic Test Mode (DTM)"
- Press -> key repeatedly, until "coolant fan activation 1 " is activated.
^ Voltage value must increase up to approximately 10.5 volts (and then decrease again).
- End function "03 - output Diagnostic Test Mode (DTM)" by pressing - button.
- Select "06 - End Output".
- Switch off ignition.
If specified value is reached but fan does not run:
- Replace Coolant Fan V7.
If specification is not obtained:
- Check wire connections from harness connector at left front in engine compartment to Coolant Fan Control (FC) Control Module J293 according to wiring diagram.
If no malfunctions are detected:
- Replace Coolant Fan Control (FC) Control Module J293.
Checking Coolant Fan 2 V177 (right)
^ Fuses for Coolant Fan 2 V177 and Coolant Fan Control (FC) Control Module 2 J671 OK.
- Remove front bumper cover.
- Connect multimeter with measuring probes and connector adapters from connector test kit VAG 1594 C between terminal - 1 - and terminal - 2 - ; harness connector for Coolant Fan 2 V177 remains connected.
^ Vehicle Diagnostic, Testing and Information System VAS 5051 connected, "Vehicle Self-Diagnosis" and vehicle system "01 Engine electronics" selected. The ignition must be switched on.
Display on VAS 5051:
- In selection - 1 -, click on function "03 - output Diagnostic Test Mode (DTM)"
- Press - key repeatedly, until "coolant fan activation 2" is activated.
^ Voltage value must increase up to approximately 9 volts
- End function "03 - output Diagnostic Test Mode (DTM)" by pressing <- button.
- Select "06 - End Output".
- Switch off ignition.
If specified value is reached but fan does not run:
- Replace Coolant Fan 2 V177.
If specification is not obtained:
- Bring lock carrier into service position go to Lock carrier, moving into service position.
- Remove Coolant Fan Control (FC) Control Module 2 J671 on left front longmember - arrows -.
- Disconnect electrical harness connector - 2 - on Coolant Fan Control (FC) Control Module 2 J671.
- Connect multimeter for voltage measurement as follows.
^ Specification: approximately battery voltage respectively
If specifications are not obtained:
- Repair wire connection if necessary.
If specified values are achieved:
- Disconnect electrical harness connector - 1 - on Coolant Fan Control (FC) Control Module 2 J671.
- Connect multimeter between terminal - 1 - and - 2 - of harness connector for voltage measurement.
^ Vehicle Diagnostic, Testing and Information System VAS 5051 A connected, "Vehicle Self-Diagnosis" and vehicle system "01 Engine electronics" selected. The ignition must be switched on.
Display on VAS 5051:
- In selection - 1 -, click on function "03 - output Diagnostic Test Mode (DTM)"
- Press - button repeatedly, until "coolant fan activation 2" is activated.
^ Voltage value must decrease slowly from approximately battery voltage to approximately 8 volts (and then increase again)
- End function "03 - output Diagnostic Test Mode (DTM)" by pressing - button.
- Select "06 - End Output".
- Switch off ignition.
If specification is not obtained:
- Connect test box VAG 1598/31 to wiring harness connectors, Engine Control Module (ECM) is not connected.
- Connect Ground (GND) clip at test box to Ground (GND) (not visible in illustration).
CAUTION! To avoid damaging electronic components, set measuring range before connecting test leads and observe all test requirements.
- Check the following wire connection for open circuit and short circuit to Ground (GND) and B+:
- Repair wire connection if necessary.
If no malfunctions are detected:
- Check wire connection from Coolant Fan Control (FC) Control Module 2 J671 to harness connector on longmember - arrow -.
If no malfunctions are detected in wiring:
- Replace Coolant Fan Control (FC) Control Module 2 J671