Pinpoint Test M: The Blower Motor Is Inoperative

WARNING: This page is about a different car, the 2004 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

Test Step

Result / Action to Take

Test Step

M1 VERIFY THE BLOWER MOTOR OPERATION

Key in ON position.
Press the PANEL button on the DATC module. Adjust the blower motor setting to LO and then to HI.
Is the blower motor inoperative in all settings?

Result / Action to Take

Yes

GO to M2.

Go To PINPOINT TEST N: THE BLOWER MOTOR DOES NOT OPERATE CORRECTLY .

Test Step

M2 CHECK FOR VOLTAGE TO THE BLOWER MOTOR

Key in OFF position.
Disconnect: Blower Motor C1031.
Key in ON position.
Measure the voltage between the blower motor C1031, circuit 371 (PK/WH) and ground.

Fig 1: Checking For Voltage To The Blower Motor
Courtesy of FORD MOTOR CO.
Is the voltage greater than 10 volts?

Result / Action to Take

Yes

GO to M3.

GO to M8.

Test Step

M3 CHECK THE BLOWER MOTOR

Key in OFF position.
Connect: Blower Motor C1031.
Disconnect: Blower Motor Speed Control C1308.
Connect a fused jumper lead between the blower motor speed control C1308-4, circuit 515 (OG/RD) and C1308-5, circuit 57 (BK).

Fig 2: Checking Blower Motor
Courtesy of FORD MOTOR CO.
Key in ON position.
Does the blower motor operate?

Result / Action to Take

Yes

GO to M6.

GO to M4.

Test Step

M4 CHECK CIRCUIT 57 (BK)

Key in OFF position.
Remove the fixed jumper lead from the blower motor speed control C1308.
Measure the resistance between the blower motor speed control C1308-5, circuit 57 (BK) and ground.

Fig 3: Checking Circuit 57 (BK)
Courtesy of FORD MOTOR CO.
Is the resistance less than 5 ohms?

Result / Action to Take

Yes

GO to M5.

REPAIR circuit 57 (BK).

TEST the system for normal operation.

Test Step

M5 CHECK CIRCUIT 515 (OG/RD)

Disconnect: Blower Motor C1031.
Measure the resistance between the blower motor C1031, circuit 515 (OG/RD) and the blower motor speed control C1308-4, circuit 515 (OG/RD).

Fig 4: Checking Circuit 515 (OG/RD)
Courtesy of FORD MOTOR CO.
Is the resistance less than 5 ohms?

Result / Action to Take

Yes

INSTALL a new blower motor. TEST the system for normal operation.

REPAIR circuit 515 (OG/RD). TEST the system for normal operation.

Test Step

M6 CHECK THE DATC MODULE OUTPUT

Key in OFF position.
Remove the fused jumper lead from the blower motor speed control C1308.
Connect: Blower Motor Speed Control C1308.
Key in ON position.
Adjust the blower motor speed to HI.
Measure the voltage between the DATC module C228a-8, circuit 754 (LG/WH) and ground by back-probing the DATC module C228a.

Fig 5: Checking DATC Module Output
Courtesy of FORD MOTOR CO.
Is the voltage within 2 volts of battery voltage?

Result / Action to Take

Yes

GO to M7.

INSTALL a new DATC module. TEST the system for normal operation.

Test Step

M7 CHECK CIRCUIT 754 (LG/WH) FOR AN OPEN OR SHORT TO GROUND

Key in OFF position.
Disconnect: Blower Motor Speed Control C1308.
Disconnect: DATC Module C228a.
Measure the resistance between the DATC module C228a-8, circuit 754 (LG/WH) and the blower motor speed control C1308-3, circuit 754 (LG/WH), and measure the resistance between the DATC module C228a-8, circuit 754 (LG/WH) and ground.

Fig 6: Checking Circuit 754 (LG/WH) For Open Or Short To Ground
Courtesy of FORD MOTOR CO.
Is the resistance less than 5 ohms between the DATC module and the blower motor speed control and greater than 10,000 ohms between the DATC module and ground?

Result / Action to Take

Yes

INSTALL a new blower motor speed control.

TEST the system for normal operation.

REPAIR circuit 754 (LG/WH). TEST the system for normal operation.

Test Step

M8 CHECK CIRCUIT 371 (PK/WH)

Key in OFF position.
Disconnect: Blower Motor Relay.
Measure the resistance between the blower motor relay socket pin 87, circuit 371 (PK/WH) and the blower motor C1031, circuit 371 (PK/WH).

Fig 7: Checking Circuit 371 (PK/WH)
Courtesy of FORD MOTOR CO.
Is the resistance less than 5 ohms?

Result / Action to Take

Yes

GO to M9.

REPAIR circuit 371 (PK/WH). TEST the system for normal operation.

Test Step

M9 CHECK CIRCUIT 181 (BN/OG)

Measure the voltage between the blower motor relay socket pin 86, circuit 181 (BN/OG) and ground.

Fig 8: Checking Circuit 181 (BN/OG)
Courtesy of FORD MOTOR CO.
Is the voltage greater than 10 volts?

Result / Action to Take

Yes

GO to M10.

REPAIR circuit 181 (BN/OG). TEST the system for normal operation.

Test Step

M10 CHECK THE DATC MODULE OUTPUT

Key in ON position.
Measure the voltage between the blower motor relay socket pin 86, circuit 181 (BN/OG) and socket pin 85, circuit 364 (BK/LG).

Fig 9: Checking DATC Module Output
Courtesy of FORD MOTOR CO.
Is the voltage greater than 10 volts?

Result / Action to Take

Yes

INSTALL a new blower motor relay. TEST the system for normal operation.

GO to M11.

Test Step

M11 CHECK CIRCUIT 364 (BK/LG) FOR SHORT TO VOLTAGE

Key in OFF position.
Disconnect: DATC Module C228b.
Key in ON position.
Measure the voltage between the blower motor relay socket pin 85, circuit 364 (BK/LG) and ground.

Fig 10: Checking Circuit 364 (BK/LG) For Short To Voltage
Courtesy of FORD MOTOR CO.
Is voltage present?

Result / Action to Take

Yes

REPAIR circuit 364 (BK/LG). TEST the system for normal operation.

GO to M12.

Test Step

M12 CHECK CIRCUIT 364 (BK/LG) FOR AN OPEN

Key in OFF position.
Measure the resistance between the DATC module C228b-9, circuit 364 (BK/LG) and the blower motor relay socket pin 85, circuit 364 (BK/LG).

Fig 11: Checking Circuit 364 (BK/LG) For Open
Courtesy of FORD MOTOR CO.
Is the resistance less than 5 ohms?

Result / Action to Take

Yes

INSTALL a new DATC module. TEST the system for normal operation.

REPAIR circuit 364 (BK/LG). TEST the system for normal operation.