Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step verifies that the auxiliary HVAC control module is commanding the auxiliary blower motor to operate at HI speed to reflect the requested speed of the front auxiliary HVAC control assembly. The scan tool should display a value greater than 50 percent.
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This step tests for an internal fault of the rear seat audio (RSA) control module, or the auxiliary HVAC control module. If the Rear HVAC Fan Speed parameter changes as the fan switch speed changes, then replace the auxiliary HVAC control module. If the Rear HVAC Fan Speed parameter does not change, replace the RSA control module.
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This step verifies that the front auxiliary HVAC control assembly receives a 5-volt reference and ground from the auxiliary HVAC control module. If all 3 parameters are at 0 when the auxiliary fan HIGH speed is requested, then proceed to step 13.
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This step verifies that the auxiliary HVAC control module is commanding the auxiliary blower motor to operate at HI speed to reflect the requested speed of the front auxiliary HVAC control assembly. If the Blower Switch Pos. parameter is 15 and the auxiliary blower motor is not on HIGH then replace the auxiliary HVAC control module.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: The auxiliary blower motor is inoperative in all speed positions. | ||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||||
2 |
Important: The auxiliary blower motor switch on the rear seat audio (RSA) control module will only function if the front auxiliary blower motor switch on the front HVAC control assembly is in the AUX position.
Does the auxiliary blower motor operate properly from both the front auxiliary HVAC control assembly and the RSA control module? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | ||||||||
3 | Does the auxiliary blower motor operate in any of the speed positions? | -- | Go to Step 4 | |||||||||
4 | Does the auxiliary blower motor operate from only the front auxiliary HVAC control assembly? | -- | Go to Step 11 | Go to Step 5 | ||||||||
5 | Does the auxiliary blower motor operate from only the RSA control module? | -- | Go to Step 12 | Go to Step 6 | ||||||||
6 |
Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 7 | ||||||||
7 | Connect a test lamp between the battery positive voltage circuit of the auxiliary blower motor control processor and a good ground. Does the test lamp illuminate? | -- | Go to Step 25 | Go to Step 26 | ||||||||
Does the scan tool indicate that the Blower Motor PWM Speed data parameter is greater than the specified value? | 50% | Go to Step 9 | Go to Step 21 | |||||||||
9 |
Does the voltage measure within the specified range? | 4.5-5.5 V | Go to Step 10 | Go to Step 17 | ||||||||
10 |
Does the test lamp illuminate? | -- | Go to Step 23 | Go to Step 29 | ||||||||
Does the Rear HVAC Fan Speed parameter change with each command? | -- | Go to Step 21 | Go to Step 20 | |||||||||
With a scan tool, observe the following parameters in the Rear Aux. Climate Module Scan Tool Data List:
Does the scan tool indicate that each parameter is 0? | -- | Go to Step 13 | Go to Step 15 | |||||||||
13 |
Does the voltage measure at least 5 volts? | -- | Go to Step 24 | Go to Step 14 | ||||||||
14 | Measure the voltage of the 5-volt reference circuit of the front auxiliary HVAC control assembly to a good ground. Does the voltage measure at least 5 volts? | -- | Go to Step 19 | Go to Step 18 | ||||||||
Does the scan tool indicate that Blower Switch Pos. parameter is 15? | -- | Go to Step 21 | Go to Step 16 | |||||||||
16 | Test the auxiliary front blower motor switch signal circuit between the front auxiliary HVAC control assembly and the auxiliary HVAC control module for a short to ground, short to voltage, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 24 | ||||||||
17 | Test the auxiliary blower motor speed control circuit between the auxiliary blower motor control processor and the auxiliary HVAC control module for a short to ground, short to voltage, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 22 | ||||||||
18 | Test the 5-volt reference circuit of the front auxiliary HVAC control assembly for a short to ground, short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 21 | ||||||||
19 | Test for an open or high resistance in the low reference circuit of the front auxiliary HVAC control assembly. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you correct the condition? | -- | Go to Step 32 | Go to Step 21 | ||||||||
20 | Inspect for poor connections at the harness connector of the RSA 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 32 | Go to Step 28 | ||||||||
21 | 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 32 | Go to Step 31 | ||||||||
22 | 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 32 | Go to Step 29 | ||||||||
23 | 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 32 | Go to Step 30 | ||||||||
24 | Inspect for poor connections at the harness connector of the front auxiliary HVAC control assembly. 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 32 | Go to Step 27 | ||||||||
25 | Repair an open or high resistance in the ground circuit of the auxiliary blower motor control processor. Refer to Wiring Repairs in Wiring Systems. Did you correct the condition? | -- | Go to Step 32 | -- | ||||||||
26 | Repair an open or short to ground in the battery positive voltage circuit of the auxiliary blower motor control processor. Refer to Wiring Repairs in Wiring Systems. Did you correct the condition? | -- | Go to Step 32 | -- | ||||||||
27 | Replace the front auxiliary HVAC control assembly. Refer to Auxiliary Heater and Air Conditioning Control Replacement - Front in Heating, Ventilation and Air Conditioning. Did you complete the replacement? | -- | Go to Step 32 | -- | ||||||||
28 | Replace the RSA control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 32 | -- | ||||||||
29 | Replace the auxiliary blower motor control processor. Refer to Auxiliary Blower Motor Processor Replacement . Did you complete the replacement? | -- | Go to Step 32 | -- | ||||||||
30 | Replace the auxiliary blower motor. Refer to Auxiliary Blower Motor Replacement in Heating, Ventilation and Air Conditioning. Did you complete the replacement? | -- | Go to Step 32 | -- | ||||||||
31 | Replace the auxiliary HVAC control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 32 | -- | ||||||||
32 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2 | ||||||||
