Test Procedure

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AH1 PRELIMINARY DIAGNOSIS

Key in OFF position.
Record the freeze frame data.
Carry out the PCM self-test.

Are any DTCs present?

Yes	No
For DTC P0480, GO to AH4. For DTC P0528, GO to AH3. For all others, REFER to DIAGNOSTIC TROUBLE CODE (DTC) DESCRIPTIONS .	GO to AH2.

AH2 CHECK THE COOLING FAN FOR MECHANICAL BINDING

NOTE: The VDF is a viscous coupling. The viscous drag should be smooth during fan rotation. The amount of resistance is dependant upon the final VDF operational state before engine shutdown.

Key in OFF position.
Manually rotate the cooling fan.

Does the fan clutch rotation feel rough or binding?

Yes	No
INSTALL a new VDF. REFER to ENGINE COOLING .	GO to AH3.

AH3 CHECK THE VDF OPERATION

NOTE: Check and verify the most current PCM calibration level.

NOTE: Inherent to viscous clutches is a delay in transitioning from a low to a high speed or from a high to a low speed. This delay can vary between 10 seconds and 3 minutes and is dependant upon engine speed and clutch temperature. With the engine at operating temperature and at 2,500 RPM, the delay should be less than 30 seconds.

Key ON, engine running.
Access the PCM and monitor the FANSS and RPM PIDs.
Increase the engine speed to 2,500 RPM.
Monitor the FANSS PID and the VDF duty cycle.
Access the PCM and control the VDF to LOW.
Allow the fan speed to stabilize below 600 RPM.
Access the PCM and control the VDF duty cycle to HIGH.

Does the fan speed change and does the FANSS PID indicate an RPM change?

Yes	No
If the FANSS PID stabilizes at less than 2,800 RPM with the engine speed at 2,500 RPM, INSTALL a new VDF. REFER to ENGINE COOLING . CLEAR the DTCs. REPEAT the self-test. If the FANSS PID stabilizes at greater than 2,800 RPM with the engine speed at 2,500 RPM, the system is operating correctly. CLEAR the DTCs. REPEAT the self-test. For cooling system concerns, REFER to ENGINE COOLING for diagnosis and testing. CLEAR the DTCs. REPEAT the self-test.	If the fan speed did not change, GO to AH4. If the fan speed did change and the FANSS PID did not indicate an RPM change, GO to AH10.

Yes

If the FANSS PID stabilizes at less than 2,800 RPM with the engine speed at 2,500 RPM, INSTALL a new VDF. REFER to ENGINE COOLING . CLEAR the DTCs. REPEAT the self-test.
If the FANSS PID stabilizes at greater than 2,800 RPM with the engine speed at 2,500 RPM, the system is operating correctly. CLEAR the DTCs. REPEAT the self-test.
For cooling system concerns, REFER to ENGINE COOLING for diagnosis and testing. CLEAR the DTCs. REPEAT the self-test.

If the fan speed did not change, GO to AH4.
If the fan speed did change and the FANSS PID did not indicate an RPM change, GO to AH10.

AH4 CHECK THE VDF SOLENOID RESISTANCE

Key in OFF position.
Cooling Fan Clutch connector disconnected.

Measure the resistance between:

( + ) VDF Connector, Component Side	( - ) VDF Connector, Component Side
VPWR - Pin 5	VDF - Pin 4

Is the resistance between 6 - 10 ohms?

Yes	No
GO to AH5.	INSTALL a new VDF. REFER to ENGINE COOLING . CLEAR the DTCs. REPEAT the self-test.

AH5 CHECK THE VDF SOLENOID FOR A SHORT TO GROUND

Measure the resistance between:

( + ) VDF Connector, Component Side	( - )
VDF - Pin 4	Ground

Is the resistance greater than 10K ohms?

Yes	No
GO to AH6.	INSTALL a new VDF. REFER to ENGINE COOLING . CLEAR the DTCs. REPEAT the self-test.

AH6 CHECK THE VDF SOLENOID VPWR CIRCUIT FOR VOLTAGE

Key ON, engine OFF.

Measure the voltage between:

( + ) VDF Connector, Harness Side	( - )
VPWR - Pin 5	Ground

Is the voltage greater than 10.5 V?

Yes	No
GO to AH7.	REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.

AH7 CHECK THE VDF SOLENOID CONTROL CIRCUIT FOR AN OPEN

Key in OFF position.
PCM connector disconnected.

Measure the resistance between:

( + ) VDF Connector, Harness Side	( - ) PCM Connector, Harness Side
VDF - Pin 4	VDF - Pin E14

Is the resistance less than 5 ohms?

Yes	No
GO to AH8.	REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.

AH8 CHECK THE VDF SOLENOID CONTROL CIRCUIT FOR A SHORT TO GROUND

Measure the resistance between:

( + ) VDF Connector, Harness Side	( - )
VDF - Pin 4	Ground

Is the resistance greater than 10K ohms?

Yes	No
GO to AH9.	REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.

AH9 CHECK THE VDF CONTROL CIRCUIT FOR A SHORT TO POWER

Key ON, engine OFF.

Measure the voltage between:

( + ) VDF Connector, Harness Side	( - )
VDF - Pin 4	Ground

Is any voltage present?

Yes	No
REPAIR the short circuit to PWR. CLEAR the DTCs. REPEAT the self-test.	GO to AH19.

AH10 CHECK THE FAN SPEED SENSOR FOR VOLTAGE

Key in OFF position.
VDF connector disconnected.

Measure the voltage between:

( + ) VDF Connector, Harness Side	( - ) VDF Connector, Harness Side
VBPWR - Pin 6	FSS SIGRTN - Pin 2

Is the voltage greater than 10.5 V?

Yes	No
GO to AH15.	GO to AH11.

AH11 CHECK THE VBPWR CIRCUIT FOR VOLTAGE

Measure the voltage between:

( + ) VDF Connector, Harness Side	( - )
VBPWR - Pin 6	Ground

Is the voltage greater than 10.5 V?

Yes	No
GO to AH14.	GO to AH12.

AH12 CHECK THE VBPWR CIRCUIT FOR AN OPEN

Key in OFF position.
PCM connector disconnected.

Measure the resistance between:

( + ) VDF Connector, Harness Side	( - ) PCM Connector, Harness Side
VBPWR - Pin 6	VBPWR - Pin E46

Is the resistance less than 5 ohms?

Yes	No
GO to AH13.	REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.

AH13 CHECK THE VBPWR CIRCUIT FOR A SHORT TO GROUND

Key in OFF position.
PCM connector disconnected.

Measure the resistance between:

( + ) VDF Connector, Harness Side	( - )
VBPWR - Pin 6	Ground

Is the resistance greater than 10K ohms?

Yes	No
GO to AH19.	REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.

AH14 CHECK THE FAN SPEED SENSOR FSS SIGRTN CIRCUIT FOR AN OPEN

Key in OFF position.
PCM connector disconnected.

Measure the resistance between:

( + ) VDF Connector, Harness Side	( - ) PCM Connector, Harness Side
FSS SIGRTN - Pin 2	FSS SIGRTN - Pin E22

Is the resistance less than 5 ohms?

Yes	No
GO to AH19.	REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.

AH15 CHECK THE FAN SPEED SENSOR SIGNAL CIRCUIT FOR AN OPEN

Key in OFF position.
PCM connector disconnected.

Measure the resistance between:

( + ) VDF Connector, Harness Side	( - ) PCM Connector, Harness Side
FSS - Pin 1	FSS - Pin E6

Is the resistance less than 5 ohms?

Yes	No
GO to AH16.	REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.

AH16 CHECK THE SIGNAL CIRCUIT FOR A SHORT TO GROUND

Measure the resistance between:

( + ) VDF Connector, Harness Side	( - )
FSS - Pin 1	Ground

Is the resistance greater than 10K ohms?

Yes	No
GO to AH17.	REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.

AH17 CHECK THE SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE

Key ON, engine OFF.

Measure the voltage between:

( + ) VDF Connector, Harness Side	( - )
FSS - Pin 1	Ground

Is any voltage present?

Yes	No
REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.	GO to AH18.

AH18 CHECK THE SIGNAL CIRCUIT FOR VOLTAGE

Key in OFF position.
PCM connector connected.
Key ON, engine OFF.

Measure the voltage between:

( + ) VDF Connector, Harness Side	( - )
FSS - Pin 1	Ground

Is the voltage greater than 10 V?

Yes	No
INSTALL a new VDF. REFER to ENGINE COOLING . CLEAR the DTCs. REPEAT the self-test.	GO to AH19.

AH19 CHECK FOR CORRECT PCM OPERATION

Disconnect all the PCM connectors.
Visually inspect for:
- pushed out pins
- corrosion
Connect all the PCM connectors and make sure they seat correctly.
Carry out the PCM self-test and verify the concern is still present.

Is the concern still present?

Yes	No
INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) .	The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.