Auxiliary Blower Motor Malfunction
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Auxiliary Blower Motor Malfunction
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Diagnostic Fault Information
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Circuit
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Short to Ground
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Open/High Resistance
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Short to Voltage
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Signal Performance
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Rear Blower Motor Control Module B+
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B0208 06
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B0208 06
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-
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-
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Rear Blower Motor B+
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1
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1
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-
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-
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Rear Blower Motor Control Module Control
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B0208 06
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B0208 06
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B0208 01
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-
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Rear Blower Motor Control
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2
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1
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1
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-
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Rear Blower Motor Control Module Ground
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-
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1
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-
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-
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1. Rear Blower Motor Inoperative
2. Rear Blower Motor Always ON
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Circuit/System Description
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The blower motor control module - auxiliary is an interface between the HVAC control module and the blower motor - auxiliary. The Blower Motor Speed Control from the HVAC Control Module, battery positive and ground circuits enable the Blower Motor Control Module - Auxiliary to operate. The HVAC Control Module provides a Pulse Width Modulation (PWM) signal to the Blower Motor Control Module - Auxiliary in order to command the blower motor speed. The Blower Motor Control Module - Auxiliary transfers the PWM signal into a corresponding blower motor voltage. The voltage amounts to between 2-13 V and changes linear to the reading of the PWM signal.
Check the following mechanical fault sources:
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Air distribution hoses/air distribution ducts
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Schematic Reference
HVAC Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Automatic HVAC Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References
for scan tool information
Circuit/System Verification
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1.
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Ignition ON, press and release the blower speed increase switch. Verify the scan tool Auxiliary Blower Motor Switch parameter. The reading should correspond to the selected blower step.
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2.
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If not the specified value, replace the A21 Radio/HVAC Controls - Auxiliary.
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3.
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Press and release the blower speed decrease switch. Verify the scan tool Auxiliary Blower Motor Switch parameter. The reading should correspond to the selected blower step.
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4.
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If not the specified value, replace the A21 Radio/HVAC Controls - Auxiliary.
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1.
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Ignition OFF, disconnect the X1 harness connector at the K8A Blower Motor Control Module - Auxiliary.
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2.
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Verify that a test lamp illuminates between the K8A Blower Motor Control Module - Auxiliary ground circuit terminal 4 X1 and B+.
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3.
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If the test lamp does not illuminate, test the ground circuit for an open circuit/high resistance.
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4.
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Ignition ON, verify that a test lamp illuminates between the K8A Blower Motor Control Module - Auxiliary B+ circuit terminal 2 X1 and ground.
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5.
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If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
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6.
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Ignition OFF, disconnect the harness connector at the M8B Blower Motor - Auxiliary and connect the X1 harness connector at the K8A Blower Motor Control Module - Auxiliary.
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7.
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Ignition ON, verify that a test lamp illuminates between the M8B Blower Motor - Auxiliary B+ circuit terminal B and ground.
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8.
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If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K8A Blower Motor Control Module - Auxiliary.
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9.
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Connect a test lamp between the M8B Blower Motor - Auxiliary B+ circuit terminal B and the M8B Blower Motor - Auxiliary control circuit terminal A.
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10.
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Turn the blower motor to high speed then to low speed. The test lamp intensity should be bright when in high speed and very dim or off when the blower is on low speed.
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11.
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If the test lamp illuminates brightly continuously, test the control circuit for a short to ground. If the circuit tests normal, replace the K8A Blower Motor Control Module - Auxiliary and verify that the test lamp does not always illuminate brightly. If the test lamp always illuminates brightly, replace the K33 HVAC Control Module.
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12.
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If the test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K8A Blower Motor Control Module - Auxiliary and verify that the test lamp illuminates. If the test lamp does not illuminate, replace the K33 HVAC Control Module.
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13.
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If the test lamp intensity does not vary, replace the K8A Blower Motor Control Module - Auxiliary and verify that the intensity varies. If the test lamp intensity does not vary, replace the K33 HVAC Control Module.
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14.
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If all circuits test normal, replace the M8B Blower Motor - Auxiliary.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
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TBD Link 63259 [Auxiliary Heater and Air Conditioning Control Module Replacement ]
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•
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TBD Link 192699 [ Auxiliary Blower Assembly Replacement ]
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