Blower Motor Malfunction
Blower Motor Malfunction
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Circuit/System Description
The blower motor switch applies ground to the blower motor control circuit that corresponds to the selected blower speed. The resistors and the blower motor are in a series circuit. The following list represents the number of resistors in series with the blower motor per particular speed request:
* Low speed, 3 resistors
* Medium 1 speed, 2 resistors
* Medium 2 speed, 1 resistors
When blower switch is in the Hi speed position, ground is applied directly to the blower motor through the blower switch.
Diagnostic Aids
Prior to motor replacement connect a direct independent B+ and ground to verify operation.
Inspect the motor shaft for rust or other foreign material which may prohibit proper motor operation.
If the motor operates properly please reinstall it, check for PIs or TSBs, and refer to Testing for Intermittent Conditions and Poor Connections in the Electrical Information Reference section of this document.
Reference Information
Schematic Reference
HVAC Schematics Electrical Diagrams
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
Manual HVAC Description and Operation HVAC - Manual
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Circuit/System Verification
1. Ignition ON
2. Verify the blower motor operates in all speed positions
• If the blower motor does not operate in any speed positions
Refer to the Blower Motor Circuit Test
• If the blower motor operates in one or more, but not all speed positions
Refer to the Blower Motor Switch Circuit Test
• If the blower motor operates in all speed positions
3. All OK
Circuit/System Testing
Blower Motor Circuit Test
1. Ignition OFF, disconnect the KR32E blower motor relay.
2. Test for less than 5 ohms between the ground circuit terminal R5 1 and ground.
• If 5 ohms or greater
1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 5 ohms
3. Ignition ON.
4. Verify a test lamp illuminates between the B+ circuit terminal R5 3 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF.
2. Test for less than 2 ohms in the B+ circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is good and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF, disconnect the harness connector at the M8 blower motor and remove the 10 A F32DA fuse.
2. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for infinite resistance between the control circuit terminal R5 5 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the M8 blower motor.
• If the test lamp illuminates
5. Connect a test lamp between the control circuit terminal R5 2 and the ground circuit terminal R5 1, ignition ON.
6. Verify the test lamp turns ON and OFF when commanding the BCM Run Relay ON and OFF with a scan tool.
• If the test lamp is always OFF
1. Ignition OFF, disconnect the harness connector at the K9 body control module
2. Test for infinite resistance between the control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K9 body control module
• If the test lamp is always ON
1. Ignition OFF, disconnect the harness connector at the K9 body control module, ignition ON.
2. Test for less than 1 V between the control circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K9 body control module.
• If the test lamp turns ON and OFF
7. Verify that a test lamp does not illuminate between the control circuit terminal R5 5 and ground.
• If the test lamp illuminates
Repair the short to voltage on the control circuit.
• If the test lamp does not illuminate
8. Ignition OFF and all vehicle systems OFF, disconnect the X1 harness connector at the K33 HVAC control module. It may take up to 2 minutes for all vehicle system to power down.
9. Test for less than 5 ohms between the ground circuit terminal 1 and ground.
• If 5 ohms or greater
1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 5 ohms
10. Ignition OFF, connect the harness connector at the K33 HVAC control module and disconnect the harness connector at the R3 blower motor resistor.
11. Place the blower motor switch in the high speed position.
12. Test for less than 5 ohms between the control circuit terminal D and ground.
• If 5 ohms or greater
1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC control module.
2. Test for less than 2 ohms in the control circuit terminal end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K33 HVAC control module.
• If less than 5 ohms
13. Ignition OFF, connect the harness connector at the R3 blower motor resistor and disconnect the harness connector at the M8 Blower Motor. Place the blower motor switch in the high speed position.
14. Test for less than 5 ohms between the control circuit terminal 1 and ground.
• If 5 ohms or greater
1. Ignition OFF, disconnect the harness connector at the R3 blower motor resistor.
2. Test for less than 2 ohms in the control circuit terminal end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the R3 blower motor resistor.
• If less than 5 ohms
15. Connect the harness connector at the M8 blower motor.
16. Ignition ON, connect a 30 A fused jumper wire between the B+ circuit terminal R5 3 and the control circuit terminal R5 5
17. Verify the M8 blower motor is activated.
• If the blower motor does not activate
1. Ignition OFF, disconnect the harness connector at the M8 blower motor.
2. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the M8 blower motor.
• If the blower motor activates
18. Test or replace the KKR32E blower motor relay.
Blower Motor Switch Circuit Test
1. Ignition OFF, disconnect the harness connector at the R3 blower motor resistor.
2. Place the blower motor switch in the OFF position.
3. Test for less than 1 V between the appropriate control circuit terminal listed below and ground:
* Blower speed 1 terminal E
* Blower speed 2 terminal A
* Blower speed 3 terminal B
* Blower speed 4 terminal D
• If 1 V or greater
1. Disconnect the X 1 harness connector at the K33 HVAC control module.
2. Test for less than 1 V between the control circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K33 HVAC control module.
• If less than 1 V
4. Place the blower motor switch in the OFF position.
5. Test for infinite resistance between the control circuit terminals lister below and ground:
* Blower speed 1 terminal E
* Blower speed 2 terminal A
* Blower speed 3 terminal B
* Blower speed 4 terminal D
• If less than infinite resistance
1. Disconnect the X 1 harness connector at the K33 HVAC control module.
2. Test for infinite resistance between the control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K33 HVAC control module.
• If infinite resistance
6. Test for less than 5 ohms between the control circuit terminals listed below and ground with the blower switch in the appropriate position.
* Blower speed 1 terminal E
* Blower speed 2 terminal A
* Blower speed 3 terminal B
* Blower speed 4 terminal D
• If 5 ohms or greater
1. Disconnect the X 1 harness connector at the K33 HVAC control module.
2. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K33 HVAC control module.
• If less than 5 ohms
7. Test or replace the R3 blower motor resistor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic repair.
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