Pinpoint Test O: The Blower Motor Does Not Operate Correctly
Climate Control System
Pinpoint Test O: The Blower Motor Does Not Operate Correctly
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information Electrical Diagrams.
Normal Operation
Under normal operation, the blower motor is provided a ground through part of the blower resistor in LO, MED-LO and MED-HI blower setting. The blower motor resistor is grounded through the blower motor switch in any setting except HI. In HI, the blower motor is grounded directly through the blower motor switch. The blower switch is provided a ground. The blower motor switch is part of the HVAC module and can not be replaced separately.
- DTC 51 (Blower Relay Driver Circuit/Performance)- This DTC sets when any of the following occur:
- The module senses ground on the relay coil ground circuit when the relay is not grounded by the HVAC module, indicating a short directly to ground.
- The module senses voltage on the relay coil ground circuit when the relay is grounded by the HVAC module, indicating a short directly to voltage.
- The module senses no voltage on the relay coil ground circuit when the relay is not grounded by the HVAC module, indicating an open.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Blower motor resistor
- HVAC module
PINPOINT TEST O : THE BLOWER MOTOR DOES NOT OPERATE CORRECTLY
O1 CHECK THE HVAC MODULE FOR DTCs
- Ignition ON.
- CARRY OUT the HVAC module self-test.
- Check for HVAC DTCs retrieved during the self-test.
Is DTC 51 present?
Yes
REPAIR circuit CH123 (VT/GN) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to O2.
O2 CHECK THE BLOWER MOTOR OPERATION
- 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 will not turn off, REPAIR circuit CH402 (YE/GN) for a short to voltage. TEST the system for normal operation.
If the blower motor does not operate in HI setting only, GO to O3.
If the blower motor does not operate in LO, MED-LO or MED-HI setting only, GO to O4.
If the blower motor operates in HI setting only, GO to O6.
For all other symptoms, GO to O7.
No
GO to Pinpoint Test N Pinpoint Test N: The Blower Motor is Inoperative.
O3 CHECK THE BLOWER MOTOR GROUND CIRCUIT TO THE BLOWER MOTOR SWITCH FOR AN OPEN
- Ignition OFF.
- Disconnect: HVAC Module C228B.
- Disconnect: Blower Motor C2004.
- Measure the resistance between HVAC module C228B-6, circuit CH430 (VT/OG), harness side and blower motor C2004-2, circuit CH430 (VT/OG), harness side.
Is the resistance less than 5 ohms?
Yes
GO to O9.
No
REPAIR circuit CH430 (VT/OG) for an open. TEST the system for normal operation.
O4 CHECK THE BLOWER MOTOR RESISTOR
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. 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 C293.
- Ignition ON.
- Turn the function selector switch to the FLOOR position.
- For LO inoperative
For LO inoperative: With the blower motor switch in the LO speed position, connect a 12-volt test light between blower motor resistor C293-2, circuit CH430 (VT/OG), harness side and blower motor resistor C293-4, circuit CH427 (BN), harness side.
- 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 C293-2, circuit CH430 (VT/OG), harness side and blower motor resistor C293-1, 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 C293-2, circuit CH430 (VT/OG), harness side and blower motor resistor C293-3, 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 O5.
O5 CHECK THE BLOWER MOTOR RESISTOR TO BLOWER MOTOR SWITCH CIRCUITS
- Disconnect: HVAC Module C228B.
- For LO inoperative
For LO inoperative, measure the resistance between HVAC module C228B-1, circuit CH427 (BN), harness side and blower motor resistor C293-4, circuit CH427 (BN), harness side.
- For MED-LO inoperative
For MED-LO inoperative, measure the resistance between HVAC module C228B-4, circuit CH428 (GN/WH), harness side and blower motor resistor C293-1, circuit CH428 (GN/WH), harness side.
- For MED-HI inoperative
For MED-HI inoperative, measure the resistance between HVAC module C228B-5, circuit CH429 (GY/BN), harness side and blower motor resistor C293-3, circuit CH429 (GY/BN), harness side.
Is the resistance less than 5 ohms?
Yes
GO to O9.
No
REPAIR circuit CH427 (BN), CH428 (GN/WH) or CH429 (GY/BN) for an open. TEST the system for normal operation.
O6 CHECK THE BLOWER MOTOR GROUND CIRCUIT TO THE BLOWER MOTOR RESISTOR FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor C2004.
- Disconnect: Blower Motor Resistor C293.
- Measure the resistance between blower motor resistor C293-2, circuit CH430 (VT/OG), harness side and blower motor C2004-2, 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) for an open. TEST the system for normal operation.
O7 CHECK THE BLOWER MOTOR RESISTOR CIRCUITS FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Blower Motor C2004.
- Disconnect: Blower Motor Resistor C293.
- Disconnect: HVAC Module C228B.
- Measure the resistance between ground and blower motor resistor:
- C293-1, circuit CH428 (GN/WH), harness side.
- C293-3, circuit CH429 (GY/BN), harness side.
- C293-2, circuit CH430 (VT/OG), harness side.
Are the resistances greater than 10,000 ohms?
Yes
GO to O8.
No
REPAIR the affected circuit for a short to ground. TEST the system for normal operation.
O8 CHECK THE BLOWER MOTOR RESISTOR CIRCUITS FOR SHORTS TOGETHER
- Measure the resistance between blower motor resistor C293, harness side using the following chart:
Blower Motor Resistor Circuit Blower Motor Resistor Circuit C293-1 CH428 (GN/WH) C293-2 CH430 (VT/OG) C293-1 CH428 (GN/WH) C293-3 CH429 (GY/BN) C293-1 CH428 (GN/WH) C293-4 CH427 (BN) C293-2 CH430 (VT/OG) C293-3 CH429 (GY/BN) C293-2 CH430 (VT/OG) C293-4 CH427 (BN) C293-3 CH429 (GY/BN) C293-4 CH427 (BN)
Are the resistances greater than 10,000 ohms?
Yes
GO to O9.
No
REPAIR the affected circuits. TEST the system for normal operation.
O9 CHECK THE HVAC MODULE CONNECTION
- Disconnect all the HVAC module connectors.
- Inspect the HVAC module connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat all the HVAC module connectors.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new HVAC module. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.