On Board Diagnostics II PCED

1999 PCED On Board Diagnostics II

SECTION 5: Pinpoint Tests

KF: Fan Control (FC) Relay

KF1 DTC P1474/P1479: CHECK VPWR VOLTAGE TO APPLICABLE FAN CONTROL RELAY

NOTE: During diagnosis, use the chart below to determine the correct circuit and relay being tested.

DTC	Circuit/ Relay
P1474	LFC
P1479	HFC

Disconnect appropriate fan control relay.
Key on, engine off.
Measure VPWR circuit voltage at the applicable fan control relay harness connector.

Is voltage greater than 10.5 volts?

Yes	No
GO to KF2 .	REPAIR open VPWR circuit to the applicable fan control relay.

KF2 CHECK FOR LFC or HFC CIRCUIT CYCLING

Key on, engine off.
Connect a non-powered test lamp between the VPWR circuit and the LFC or HFC circuit at the applicable fan control relay harness connector.
Access Output Test Mode on scan tool.
While observing test lamp, command the appropriate cooling fan speed on and off.

Does the test lamp turn on and off when the cooling fan output is commanded on and off?

Yes	No
REPLACE appropriate fan control relay.	REPEAT test step to VERIFY results. If test lamp still does not turn on and off as expected, turn KEY OFF. REMOVE test lamp. GO to KF3 .

KF3 CHECK LFC or HFC CIRCUIT FOR SHORT TO POWER IN HARNESS

Disconnect PCM.
Key on, engine off.
Measure voltage between the LFC or HFC circuit at the applicable fan relay harness connector and ground.

Is voltage less than 1.0 volt?

Yes	No
KEY OFF. GO to KF4 .	REPAIR short circuit.

KF4 CHECK LFC or HFC CIRCUIT FOR SHORT TO GROUND IN HARNESS

Disconnect scan tool from DLC.
Measure resistance between the LFC or HFC circuit at the applicable fan relay harness connector and ground.

Is resistance greater than 10,000 ohms?

Yes	No
GO to KF5 .	REPAIR short circuit.

KF5 CHECK FOR OPEN LFC or HFC CIRCUIT

Note: Refer to the PCM connector pin numbers at the beginning of this pinpoint test.

Measure resistance of the LFC or HFC circuit between the appropriate PCM harness connector pin (LFC or HFC) and the appropriate fan control relay harness connector.

Is resistance less than 5.0 ohms?

Yes	No
REPLACE PCM (refer to Section 2 , Flash EEPROM).	REPAIR open circuit.

KF10 CONTINUOUS MEMORY DTC P1474: CHECK LOW SPEED FAN CONTROL (LFC) CIRCUIT FOR OPEN OR SHORT TO POWER

A/C and defrost off.
Disconnect cooling fan connector (both for applications with two fans).
Connect a non-powered test lamp between the LOW FAN PWR circuit and ground circuit at the cooling fan harness connector (either one for applications with two fans).
Key on, engine off.
Access Output Test Mode on scan tool.
Command Low Speed Fan on.
Observe test lamp for an indication of a fault while completing the following (the lamp will turn off when a fault is detected, indicating an open or short to power):

Shake, wiggle and bend the LFC circuit between the PCM and low speed FC relay.
Shake, wiggle and bend the VPWR circuit to the low speed FC relay.
Lightly tap on the low speed FC relay to simulate road shock.

Is a fault indicated?

Yes	No
ISOLATE fault and REPAIR as necessary.	GO to KF11 .

KF11 CHECK LFC CIRCUIT FOR SHORT TO GROUND

Key on, engine off.
Command Low Speed Fan off.
Observe test lamp for an indication of a fault while completing the following (the lamp will turn on when a fault is detected, indicating LFC circuit short to ground):

Shake, wiggle and bend the LFC circuit between the PCM and low speed FC relay.
Lightly tap on the low speed FC relay to simulate road shock.

Is a fault indicated?

Yes	No
ISOLATE fault and REPAIR as necessary.	KEY OFF. GO to Pinpoint Test Step Z1 .

KF20 CONTINUOUS MEMORY DTC P1479: CHECK HIGH SPEED FAN CONTROL (HFC) CIRCUIT FOR OPEN OR SHORT TO POWER

A/C and defrost off.
Disconnect cooling fan connector(s) (both for applications with two fans).
Connect a non-powered test lamp between the HIGH FAN PWR circuit and ground circuit at the cooling fan harness connector (either one for applications with two fans).
Key on, engine off.
Access Output Test Mode on scan tool.
Command High Speed Fan on.
Observe test lamp for an indication of a fault while completing the following (the lamp will turn off when a fault is detected, indicating an open or short to power):

Shake, wiggle and bend the HFC circuit between the PCM and high speed FC relay.
Shake, wiggle and bend the VPWR circuit to the high speed FC relay.
Lightly tap on the high speed FC relay to simulate road shock.

Is a fault indicated?

Yes	No
ISOLATE fault and REPAIR as necessary.	GO to KF21 .

KF21 CHECK HFC CIRCUIT FOR SHORT TO GROUND

Command High Speed Fan off.
Observe test lamp for an indication of a fault while completing the following (the lamp will turn on when a fault is detected, indicating an HFC circuit short to ground):

Shake, wiggle and bend the HFC circuit between the PCM and high speed FC relay.
Lightly tap on the HFC relay to simulate road shock.

Is a fault indicated?

Yes	No
ISOLATE fault and REPAIR as necessary.	KEY OFF. GO to Pinpoint Test Step Z1 .

KF30 ELECTRIC COOLING FAN CONCERN (WITH NO DTCs): CHECK FAN FUNCTION

Key on, engine off.
Access Output Test Mode on scan tool.
Command the cooling fan on and check for fan operation. For two speed fan applications, check both fan speeds (wait 20 seconds after commanding high speed fan on, verify fan speed changes).

Does the fan(s) operate (all speeds)?

Yes	No
KEY OFF. Cooling fan circuits OK. RETURN to Section 3 Chart.	COMMAND cooling fan off. REMAIN in Output Test Mode. For Contour/Mystique/Cougar and Windstar : GO to KF50 . All others : GO to KF31 .

KF31 DID THE FAN(S) OPERATE AT ANY SPEED?

Note: For Taurus/Sable, if one cooling fan motor does not operate when the other motor operates, GO to KF70 .

During the operational check of both fan speeds, did the fan(s) operate at any speed?

Yes	No
Only one fan speed is operational. GO to KF40 .	Cooling fan will not operate at any speed. GO to KF32 .

KF32 COOLING FAN WILL NOT OPERATE AT ANY SPEED: COMMAND HIGH SPEED FAN ON AND CHECK FOR VOLTAGE TO COOLING FAN

Key on, engine off.
Still in Output Test Mode, with fan commanded off.
Disconnect cooling fan (both for Taurus/Sable).
Command high speed fan on.
Measure voltage between the HIGH FAN PWR circuit at the cooling fan harness connector (either one for Taurus/Sable) and chassis ground.

Is voltage greater than 10.0 volts?

Yes	No
KEY OFF. Power is being supplied to fan. GO to KF37 (to check cooling fan ground circuit).	KEY OFF. Power is not being supplied to fan. GO to KF33 .

KF33 CHECK B+ TO HIGH SPEED FC RELAY AND LOW SPEED FC RELAY

Disconnect high speed and low speed FC relays.
Measure B+ circuit voltage at the high speed FC relay harness connector.
Measure B+ circuit voltage at the low speed FC relay harness connector.

Is voltage greater than 10.0 volts?

Yes	No
GO to KF34 .	B+ circuit fault. CHECK condition of related fuses. If OK, REPAIR open circuit. If fuse is damaged, CHECK B+ and FAN PWR circuits for short to ground before replacing.

KF34 CHECK FOR OPEN HIGH FAN PWR AND LOW FAN PWR CIRCUITS

Measure resistance of the HIGH FAN PWR circuit between the High Speed FC relay harness connector and the cooling fan harness connector(s).
Measure resistance of the LOW FAN PWR circuit between the low speed FC relay harness connector and the cooling fan harness connector(s).

Are all resistances less than 5.0 ohms?

Yes	No
GO to KF35 .	REPAIR open circuit.

KF35 COMMAND LOW SPEED FAN ON AND CHECK FOR VOLTAGE TO COOLING FAN

Reconnect low speed FC relay and high speed FC relay.
Key on, engine off.
Again, enter Output Test Mode on scan tool.
Command Low Speed Fan on.
Measure LOW FAN PWR circuit voltage at the cooling fan harness connector (either one for Taurus/Sable).

Is voltage greater than 10.0 volts?

Yes	No
KEY OFF. REPLACE the High Speed FC relay, then GO to KF37 .	KEY OFF. GO to KF75 , and follow directions for low speed fan inoperative. After repair, RETURN to KF75 and follow directions for high speed fan inoperative.

KF37 CHECK COOLING FAN GROUND CIRCUIT

Disconnect scan tool from DLC.
Measure resistance of ground circuit between the cooling fan harness connector and chassis ground.

Is resistance less than 5.0 ohms?

Yes	No
REPLACE fan motor(s).	REPAIR ground circuit.

KF40 DETERMINE WHICH FAN SPEED IS OPERATIONAL

Is the low speed fan operational?

Yes	No
High speed fan inoperative. GO to KF46 .	Low speed fan inoperative. GO to KF41 .

KF41 LOW SPEED FAN INOPERATIVE: COMMAND LOW SPEED FAN ON AND CHECK FOR VOLTAGE TO COOLING FAN

Key on, engine off.
Still in Output Test Mode with fan commanded off.
Disconnect cooling fan (both for Taurus/Sable).
Command low speed fan on.
Measure LOW FAN PWR circuit voltage at the cooling fan harness connector (either one for Taurus/Sable).

Is voltage greater than 10.0 volts?

Yes	No
VERIFY ground circuit to fan. If OK, REPLACE fan motor.	KEY OFF. GO to KF42 .

KF42 CHECK B+ VOLTAGE TO LOW SPEED FAN CONTROL (FC) RELAY

Disconnect Low Speed FC relay.
Measure B+ circuit voltage at the low speed FC relay harness connector.

Is voltage greater than 10.5 volts?

Yes	No
GO to KF43 .	VERIFY condition of related fuse. If OK, REPAIR open B+ circuit. If fuse was damaged CHECK B+ and LOW FAN PWR circuit for short to ground before replacing.

KF43 CHECK FOR OPEN LOW FAN PWR CIRCUIT

Measure resistance of the LOW FAN PWR circuit between the low speed FC relay harness connector and the cooling fan harness connector(s).

Is resistance less than 5.0 ohms?

Yes	No
GO to KF75 .	REPAIR open circuit.

KF46 HIGH SPEED FAN INOPERATIVE: COMMAND HIGH SPEED FAN ON AND CHECK FOR VOLTAGE TO COOLING FAN

Key on, engine off.
Still in Output Test Mode with fan commanded off.
Disconnect cooling fan (both for Taurus/Sable).
Command high speed fan on.
Measure HIGH FAN PWR circuit voltage at the cooling fan harness connector.

Is voltage greater than 10.0 volts?

Yes	No
VERIFY ground circuit to fan. If OK, REPLACE fan motor.	KEY OFF. GO to KF47 .

KF47 CHECK B+ VOLTAGE TO HIGH SPEED FAN CONTROL (FC) RELAY

Disconnect high speed FC relay.
Measure B+ circuit voltage at the high speed FC relay harness connector.

Is voltage greater than 10.5 volts?

Yes	No
GO to KF48 .	VERIFY condition of related fuse. If OK, REPAIR open B+ circuit. If fuse was damaged, CHECK B+ and HIGH FAN PWR circuit for short to ground before replacing.

KF48 CHECK FOR OPEN HIGH FAN PWR CIRCUIT

Measure resistance of the HIGH FAN PWR circuit between the high speed FC relay harness connector and the cooling fan harness connector.

Is resistance less than 5.0 ohms?

Yes	No
GO to KF75 .	REPAIR open circuit.

KF50 LOW AND/OR HIGH SPEED COOLING FAN DOES NOT OPERATE: CHECK FOR B+ TO HIGH SPEED FC AND LOW SPEED FC RELAYS

Note: If one cooling fan motor does not operate when the other motor operates, GO to KF70 .

Disconnect high speed FC and low speed FC relays.
Measure B+ circuit voltage at both high speed FC and low speed FC relay harness connectors.

Are both voltages greater than 10.5 volts?

Yes	No
GO to KF51 .	VERIFY condition of related fuses. If OK, REPAIR open B+ circuit. If fuse was damaged, CHECK B+ and fan(s) PWR circuits for short to ground before replacing.

KF51 CHECK FOR OPEN FAN PWR, FAN GROUND AND INTERNAL FAN CIRCUITS

Measure resistance between battery negative post and the FAN PWR circuit at both the high speed FC and low speed FC relay harness connectors.

Are both resistances less than 15.0 ohms?

Yes	No
GO to KF52 .	GO to KF56 .

KF52 CHECK FAN PWR CIRCUIT FOR SHORT TO GROUND IN HARNESS

Disconnect both cooling fans.
Measure resistance between the FAN PWR circuit in harness and ground.

Is resistance greater than 10,000 ohms?

Yes	No
GO to KF53 .	REPAIR FAN PWR circuit short to ground.

KF53 CHECK HIGH SPEED FC AND LOW SPEED FC RELAY OPERATION

Reconnect high speed FC and low speed FC relays.
Key on, engine off.
Access Output Test Mode on scan tool.
Check high speed FC relay operation:

Command high speed fan on, wait 15 seconds.
Measure voltage to the FAN PWR circuit at the cooling fan harness connector (either one).
Voltage must be greater than 10.5 volts.

Check low speed FC relay operation:

Command low speed fan on.
Measure voltage to the FAN PWR circuit at the cooling fan connector (either one).
Voltage must be greater than 10.0 volts.

Do the high speed FC and low speed FC relays operate correctly?

Yes	No
REPLACE cooling fan(s).	KEY OFF. NOTE which fan speed was inoperative. GO to KF75 .

KF56 CHECK FOR OPEN FAN PWR CIRCUIT BETWEEN COOLING FAN AND THE HIGH SPEED FC AND LOW SPEED FC RELAYS

Disconnect cooling fan (either one).
Measure resistance of FAN PWR circuit between cooling fan harness connector and both the high speed FC and low speed FC relay harness connectors.

Are both resistances less than 15.0 ohms?

Yes	No
GO to KF57 .	REPAIR open in FAN PWR circuit (if open is only between low speed FC relay and fan, first verify dropping resistor connection).

KF57 CHECK COOLING FAN GROUND CIRCUIT

Measure resistance of ground circuit between the cooling fan harness connector and chassis ground.

Is resistance less than 5.0 ohms?

Yes	No
REPLACE inoperative cooling fan(s).	REPAIR ground circuit.

KF60 LOW AND/OR HIGH SPEED COOLING FAN ALWAYS RUNS (NO DTCS): VERIFY FAN IS NOT ON BECAUSE OF A/C HIGH PRESSURE SWITCH INPUT TO PCM

Start engine.
Access ACP PID.

Is the ACP PID "CLOSED"?

Yes	No
The PCM will turn the cooling fan on when the A/C high pressure switch input is "closed". Leave engine running. GO to KF61 .	Input OK. GO to KF65 .

KF61 CHECK A/C HIGH PRESSURE SWITCH (the medium pressure, normally open contacts)

Disconnect A/C high pressure switch.
Again, view the ACP PID on scan tool.

Is the ACP PID still "CLOSED"?

Yes	No
KEY OFF. GO to KF62 (to check A/C high pressure switch input to PCM).	KEY OFF. RECONNECT A/C high pressure switch. GO to the Climate Control System, General Information Section 412-00 of the Workshop Manual to check for proper A/C high pressure switch function, over-pressurized A/C system and other checks as directed.

KF62 CHECK ACPSW CIRCUIT FOR SHORT TO GROUND IN HARNESS

Disconnect scan tool from DLC.
Disconnect PCM.
Measure resistance between PCM harness connector Pin 86 and ground.

Is resistance greater than 10,000 ohms?

Yes	No
REPLACE PCM (refer to Section 2 , Flash EEPROM).	REPAIR short circuit.

KF63 LOW AND/OR HIGH SPEED COOLING FAN ALWAYS RUNS (NO DTCS): VERIFY FAN IS NOT ON BECAUSE OF A/C PRESSURE SENSOR INPUT TO PCM

A/C off.
Start engine.
Access ACP V PID.

Is the ACP V PID greater than 3.0 volts?

Yes	No
KEY OFF. GO to the Climate Control System, General Information Section 412-00 of the Workshop Manual to check for high A/C system pressure and other checks as directed.	Input is not causing the fan to run. GO to KF65 .

KF65 CHECK FOR LOW SPEED FC RELAY ALWAYS CLOSED

Note: Verify A/C and defrost are off.

Disconnect low speed FC relay.
Key on, engine off.

Does fan continue to run?

Yes	No
KEY OFF. GO to KF66 .	KEY OFF. GO to KF80 .

KF66 CHECK HIGH SPEED FC RELAY

Low speed FC relay disconnected.
Disconnect high speed FC relay.
Key on, engine off.

Does fan continue to run?

Yes	No
For Contour/Mystique/Cougar and Windstar: REPAIR FAN PWR circuit for short to power. All others: KEY OFF. GO to KF67 .	KEY OFF. GO to KF80 .

KF67 CHECK LOW FAN PWR CIRCUIT FOR SHORT TO POWER IN HARNESS

Disconnect cooling fan(s) (both for Taurus/Sable).
Key on, engine off.
Measure voltage to the LOW FAN PWR circuit at the cooling fan harness connector.

Is voltage less than 1.0 volt?

Yes	No
REPAIR HIGH FAN PWR circuit for short to power.	REPAIR LOW FAN PWR circuit for short to power.

KF70 ONE COOLING FAN MOTOR DOES NOT OPERATE WHEN THE OTHER COOLING FAN MOTOR OPERATES (NO DTCs): CHECK FOR OPEN GROUND CIRCUIT TO INOPERATIVE FAN

Disconnect inoperative cooling fan.
Measure resistance of ground circuit between cooling fan harness connector and ground.

Is resistance less than 5.0 ohms?

Yes	No
GO to KF71 .	REPAIR open circuit.

KF71 COMMAND FAN ON AND CHECK FOR POWER TO FAN

Disconnect the other cooling fan (so both are disconnected).
Access Output Test Mode on scan tool.
Command high speed fan on.
Measure voltage to the (HIGH) FAN PWR circuit at the inoperative fan harness connector.
For Taurus/Sable:

Command low speed fan on.
Measure voltage to the LOW FAN PWR circuit at the inoperative fan harness connector.

Is voltage greater than 10.0 volts (both voltages for Taurus/Sable)?

Yes	No
REPLACE inoperative cooling fan.	REPAIR open in FAN PWR circuit (HIGH or LOW for Taurus/Sable) between inoperative cooling fan and splice to other fan.

KF75 IS SCAN TOOL CAPABLE OF VIEWING PIDS WHILE IN OUTPUT TEST MODE?

Note: The symptom low speed fan or high speed fan inoperative can be caused by a primary circuit fault, even though a DTC was not set. The next test step will check the primary circuit operation.

Is scan tool being used capable of viewing PIDs while in Output Test Mode?

Yes	No
GO to KF76 .	For low speed fan inoperative: GO to KF78 . For high speed fan inoperative: GO to KF79 .

KF76 CHECK OPERATION OF LOW SPEED FAN OR HIGH SPEED FAN PRIMARY CIRCUITS

Reconnect cooling fan and low speed or high speed fan control relay.
Key on, engine off.
Enter Output Test Mode on scan tool.
For low speed fan inoperative:

Access LFC and LFCF PIDs.
With LFC PID off (low speed fan commanded off by PCM), the LFCF PID must be NO.
Command the Low Speed Fan on (the LFC PID will now be on).
The LFCF PID must still be NO.

For high speed fan inoperative:

Access HFC and HFCF PIDs.
With HFC PID off (high speed fan commanded off by PCM), the HFCF PID must be NO.
Command the high speed fan on (the HFC PID will now be on).
The HFCF PID must still be NO.

Is the HFCF or LFCF PID Yes with the fan commanded on or off?

Yes	No
KEY OFF. An HFC or LFC primary fault is detected. If the HFCF PID was yes: GO to KF1 and follow DTC P1479 diagnosis. If the LFCF PID was yes: GO to KF1 and follow DTC P1474 diagnosis.	Primary circuits OK. For low speed fan inoperative, REPLACE the low speed FC relay. For high speed fan inoperative, REPLACE the high speed FC relay. VERIFY applicable FAN PWR circuit is not short to ground.

KF78 CHECK OPERATION OF LOW SPEED FAN PRIMARY CIRCUITS

Reconnect cooling fan (if it was disconnected).
Key on, engine off.
Connect a non-powered test lamp between the VPWR circuit and the LFC circuit at the low speed FC relay harness connector.
Access Output Test Mode on scan tool.
While observing test lamp, command the low speed fan on and off.

Does the test lamp turn on and off when the cooling fan output is commanded on and off?

Yes	No
Primary circuits OK. REPLACE the low speed FC relay. VERIFY applicable FAN PWR circuit is not short to ground.	KEY OFF. An LFC primary fault is detected. GO to KF1 and follow DTC P1474 diagnosis.

KF79 CHECK OPERATION OF HIGH SPEED FAN PRIMARY CIRCUITS

Reconnect cooling fan (if it was disconnected).
Key on, engine off.
Connect a non-powered test lamp between the VPWR circuit and the HFC circuit at the high speed FC relay harness connector.
Access Output Test Mode on scan tool.
While observing test lamp, command the high speed fan on (wait 15 seconds) and off.

Does the test lamp turn on and off when the cooling fan output is commanded on and off?

Yes	No
Primary circuits OK. REPLACE the high speed FC relay. VERIFY applicable FAN PWR circuit is not short to ground.	KEY OFF. A HFC primary fault is detected. GO to KF1 and follow DTC P1479 diagnosis.

KF80 CHECK OPERATION OF LOW SPEED FAN OR HIGH SPEED FAN PRIMARY CIRCUITS

Note: The symptom cooling fan always runs, can be caused by a primary circuit fault, even though a DTC was not set. This step will check the primary circuit operation.

Reconnect FC relay(s).
Key on, engine off.
If fan stops running with the low speed FC relay disconnected:

Access LFC and LFCF PIDs.
With LFC PID off (low speed fan commanded off by PCM), the LFCF PID must be NO.

If fan stops running with the high speed FC relay disconnected:

Access HFC and HFCF PIDs.
With HFC PID off (high speed fan commanded off by PCM), the HFCF PID must be NO.

Is the HFCF or LFCF PID Yes with the fan commanded off?

Yes	No
KEY OFF. An HFC or LFC primary circuit fault is detected. If the HFCF PID was yes: GO to KF1 and follow DTC P1479 diagnosis. If the LFCF PID was yes: GO to KF1 and follow DTC P1474 diagnosis.	Primary circuits OK. If fan stopped running with the low speed FC relay disconnected, REPLACE the low speed FC relay. If fan stopped running with the high speed FC relay disconnected, REPLACE the high speed FC relay.