Pinpoint Test K: The Blower Motor Does Not Operate Correctly
Climate Control System
Pinpoint Test K: The Blower Motor Does Not Operate Correctly
Normal Operation
Under normal operation, the blower motor is provided a ground from the blower resistor. The blower motor is grounded though the entire resistor in the lowest blower setting. In MED-LO and MED-HI the blower motor is grounded through a part of the resistor, depending on selected speed. In HI, the blower motor is grounded directly through the blower switch. The blower switch is continuously grounded.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Blower motor resistor
- Blower motor switch
PINPOINT TEST K : THE BLOWER MOTOR DOES NOT OPERATE CORRECTLY
K1 CHECK THE BLOWER MOTOR OPERATION
- Ignition ON.
- Turn the function selector switch to the FLOOR position.
- Select all blower speed positions.
Does the blower motor operate in any position?
Yes
If the blower motor does not operate in HI setting only, GO to K2.
If the blower motor does not operate in LO setting only, GO to K3.
If the blower motor does not operate in MED-LO or MED-HI setting only, GO to K4.
If the blower motor operates in HI setting only, GO to K6.
If the blower motor operates in LO setting only, GO to K7.
For all other symptoms, GO to K8.
No
GO to Pinpoint Test J. Pinpoint Test J: The Blower Motor is Inoperative
K2 CHECK THE BLOWER MOTOR GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Switch C294B.
- Disconnect: Blower Motor C1227.
- Measure the resistance between blower motor switch C294B-2, circuit CH430 (VT/OG), harness side and blower motor C1227-2, circuit CH430 (VT/OG), harness side.
Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor switch. TEST the system for normal operation.
No
REPAIR circuit CH430 (VT/OG) for an open. TEST the system for normal operation.
K3 CHECK BLOWER MOTOR RESISTOR GROUND
- Disconnect: Blower Motor Resistor C1228.
- Measure the resistance between blower motor resistor C1228-3, circuit GD123 (BK/GY), harness side and ground.
Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor resistor. TEST the system for normal operation.
No
REPAIR circuit GD123 (BK/GY) for an open. TEST the system for normal operation.
K4 CHECK THE BLOWER MOTOR SWITCH
NOTICE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table at the beginning or equivalent. To avoid connector terminal damage, use the Flex Probe Kit for the test light probe connection to the vehicle. Do not use the test light probe directly on any connector.
- Ignition OFF.
- Disconnect: Blower Motor Resistor C1228.
- Ignition ON.
- For MED-LO inoperative
For MED-LO inoperative: With the blower motor switch in the MED-LO speed position, connect a 12-volt test light between blower motor resistor C1228-1, circuit CH430 (VT/OG), harness side and blower motor resistor C1228-4, circuit CH428 (GN/WH), harness side.
- For MED-HI inoperative
For MED-HI inoperative: With the blower motor switch in the MED-HI speed position, connect a 12-volt test light between blower motor resistor C1228-1, circuit CH430 (VT/OG), harness side and blower motor resistor C1228-2, circuit CH429 (GY/BN), harness side.
Does the test light illuminate?
Yes
INSTALL a new blower motor resistor. TEST the system for normal operation.
No
GO to K5.
K5 CHECK THE MED-LO AND MED-HI BLOWER MOTOR SWITCH TO BLOWER MOTOR RESISTOR CIRCUITS FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Switch C294B.
- For MED-LO inoperative
For MED-LO inoperative: Measure the resistance between blower motor switch C294B-4, circuit CH428 (GN/WH), harness side and blower motor resistor C1228-4, circuit CH428 (GN/WH), harness side.
- For MED-HI inoperative
For MED-HI inoperative: Measure the resistance between blower motor switch C294B-3, circuit CH429 (GY/BN), harness side and blower motor resistor C1228-2, circuit CH429 (GY/BN), harness side.
Is the resistance less than 5 ohms?
Yes
CARRY OUT the Blower Motor Resistor component test. If the resistor tests OK, INSTALL a new blower motor switch. TEST the system for normal operation. Component Tests
No
REPAIR circuit CH428 (GN/WH) or CH429 (GY/BN) for an open. TEST the system for normal operation.
K6 CHECK THE BLOWER MOTOR GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Resistor C1228.
- Disconnect: Blower Motor C1227.
- Measure the resistance between blower motor resistor C1228-1, circuit CH430 (VT/OG), harness side and blower motor C1227-2, circuit CH430 (VT/OG), harness side.
Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor resistor. TEST the system for normal operation.
No
REPAIR circuit CH430 (VT/OG). TEST the system for normal operation.
K7 CHECK THE BLOWER MOTOR SWITCH GROUND CIRCUIT
- Ignition OFF.
- Disconnect: Blower Motor Switch C294B.
- Measure the resistance between blower motor switch C294B-1, circuit GD116 (BK/VT), harness side and ground.
Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor switch. TEST the system for normal operation.
No
REPAIR circuit GD116 (BK/VT). TEST the system for normal operation.
K8 CHECK THE BLOWER MOTOR RESISTOR CIRCUITS FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Blower Motor C1227.
- Disconnect: Blower Motor Resistor C1228.
- Disconnect: Blower Motor Switch C294B.
- Place the blower switch in the lowest setting.
- Measure the resistance between ground and blower motor resistor:
- C1228-1, circuit CH430 (VT/OG), harness side.
- C1228-2, circuit CH429 (GY/BN), harness side.
- C1228-4, circuit CH428 (GN/WH), harness side.
Are the resistances less than 5 ohms?
Yes
GO to K9.
No
REPAIR the affected circuit for a short to ground. TEST the system for normal operation.
K9 CHECK THE BLOWER MOTOR RESISTOR CIRCUITS FOR A SHORT TOGETHER
- Measure the resistance between blower motor resistor:
- C1228-4, circuit CH428 (GN/WH), harness side and C1228-1, circuit CH430 (VT/OG), harness side.
- C1228-4, circuit CH428 (GN/WH), harness side and C1228-2, circuit CH429 (GY/BN), harness side.
- C1228-1, circuit CH430 (VT/OG), harness side and C1228-2, circuit CH429 (GY/BN), harness side.
Are the resistances greater than 10,000 ohms?
Yes
INSTALL a new blower motor switch. TEST the system for normal operation.
No
REPAIR the affected circuits for a short together. TEST the system for normal operation.