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Blower Motor Malfunction - Auxiliary (VIN 6 excluding Envoy XUV)

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
Blower Motor Malfunction - Auxiliary (VIN 6 excluding Envoy XUV)

Step Action Values Yes No
Schematic Reference: HVAC Schematics 
Connector End View Reference:  HVAC Connector End Views  
DEFINITION: The auxiliary blower motor operates in at least one speed position from at least one auxiliary control.
1 Did you perform the HVAC Diagnostic System Check? - Go to Step 2  Go to Diagnostic System Check - HVAC Systems - Automatic 
2
  1. Turn ON the ignition, with the engine OFF.
  2. With a scan tool, observe the Driver Override Switch parameter in the REAR HVAC/RSA data list.
  3. Place the front auxiliary blower motor switch in each position.
Does the scan tool indicate that the Driver Override Switch parameter changes state?		 - Go to Step 6  Go to Step 3 
3 Test the auxiliary HVAC enable control circuit of the front auxiliary blower motor switch for an open, short to voltage or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 22  Go to Step 4 
4 Test the low reference circuit of the front auxiliary blower motor switch for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 22  Go to Step 5 
5
  1. Turn OFF the ignition.
  2. Disconnect the auxiliary HVAC control module.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a volt meter between the auxiliary HVAC enable control circuit and ground.
  5. Place the front auxiliary blower motor switch from the minimum speed position to the maximum speed position.
Does the volt meter read properly for each position?		 Rear 5.0 V Off-1.0 V Pos.1 2.0 V Pos.2 3.0 V Pos.3 4.0 V Go to Step 16  Go to Step 17 
6
IMPORTANT: Ensure that the front auxiliary blower control switch is in the REAR position during the remainder of this table in order to avoid misdiagnosis.
  1. Turn ON the ignition, with the engine OFF.
  2. Place the front auxiliary blower motor switch in the REAR position.
  3. With a scan tool, observe the Rear HVAC Fan Up Switch parameter in the REAR HVAC/RSA data list.
  4. Activate the auxiliary fan up switch.
Does the scan tool indicate that the Rear Fan Up Button parameter changes state?		 - Go to Step 7  Go to Step 16 
7
  1. With a scan tool, observe the Rear HVAC Fan Down Switch parameter in the REAR HVAC/RSA data list.
  2. Activate the auxiliary fan down switch.
Does the scan tool indicate that the Rear HVAC Fan Down Switch parameter changes state?		 - Go to Step 8  Go to Step 16 
8 Place the auxiliary blower motor switch in each speed position.
Does the auxiliary blower motor operate at the desired speeds?		 - Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 9 
9
  1. Turn OFF the ignition.
  2. Disconnect the auxiliary blower motor.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the auxiliary blower motor supply voltage circuit and the auxiliary blower motor ground circuit of the auxiliary blower motor.
  5. Place the auxiliary blower motor switch from the minimum speed position to the maximum speed position.
Does the test lamp illuminate and increase intensity?		 - Go to Step 14  Go to Step 10 
10 Test the battery positive voltage circuit of the auxiliary blower motor control processor for a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 22  Go to Step 11 
11 Test the ground circuit of the auxiliary blower motor control processor for a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 22  Go to Step 12 
12
IMPORTANT: Ensure that the auxiliary blower motor control processor and auxiliary HVAC control module connectors are connected during this step in order to avoid misdiagnosis.
  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage from the auxiliary blower motor speed control circuit of the auxiliary HVAC control module to a good ground.
  3. Place the auxiliary blower motor switch from the minimum speed position to the maximum speed position.
Does the voltage continually decrease within the specified range?		 13.0-1.5 V Go to Step 15  Go to Step 13 
13
  1. Turn OFF the ignition.
  2. Disconnect the auxiliary HVAC control module.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the auxiliary blower speed control circuit of the auxiliary HVAC control module to a good ground.
Does the voltage measure near the specified value?		 8-12.5 V Go to Step 16  Go to Step 15 
14 Inspect for poor connections at the harness connector of the auxiliary blower motor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 22  Go to Step 19 
15 Inspect for poor connections at the harness connector of the auxiliary blower motor control processor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 22  Go to Step 20 
16 Inspect for poor connections at the harness connector of the auxiliary HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 22  Go to Step 21 
17 Inspect for poor connections at the harness connector of the front auxiliary blower motor switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 22  Go to Step 18 
18 Replace the front auxiliary blower motor switch. Refer to Front Auxiliary Blower Motor Switch Replacement .
Did you complete the replacement?		 - Go to Step 22  -
19 Replace the auxiliary blower motor. Refer to Blower Motor Replacement - Auxiliary (Rear Auxiliary) or Blower Motor Replacement - Auxiliary (Front Auxiliary) in Heating, Ventilation and Air Conditioning.
Did you complete the replacement?		 - Go to Step 22  -
20 Replace the auxiliary blower motor control processor. Refer to Blower Motor Processor Replacement - Auxiliary .
Did you complete the replacement?		 - Go to Step 22  -
21
IMPORTANT: Perform the recalibration procedure for the auxiliary HVAC control module.
Replace the auxiliary HVAC control module. Refer to HVAC Control Module Replacement - Auxiliary .Did you complete the replacement?		 - Go to Step 22  -
22 Operate the system in order to verify the repair.
Did you correct the condition?		 - System OK Go to Step 2 
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