Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step will determine if one or more blower speeds are inoperative.
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This step determines if the instrument panel integration module (IPM) and blower motor control processor are attempting to control the blower motor speed.
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The measured voltage on the blower motor speed control circuit should steadily decrease from 4.75 volts to 1.5 volts as the blower motor speed is adjusted from the minimum speed position to the maximum speed position.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: The blower motor operates in at least one, but not 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 |
Does the scan tool display any DTCs? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | Go to Step 3 |
Does the blower motor operate in each speed position? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 4 | |
4 |
Does scan tool indicate that the Commanded Blower parameter increases within the specified range? | 10-100% | Go to Step 5 | Go to Step 11 |
Does the test lamp illuminate and increase intensity? | -- | Go to Step 9 | Go to Step 6 | |
Test the battery positive voltage circuit and ground circuit of the blower motor control processor for high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 7 | |
7 |
Important: Ensure that the blower motor control processor and IPM connectors are connected during this step in order to avoid misdiagnosis.
Does the measured voltage decrease between the specified values? | 4.75-1.5 V | Go to Step 10 | Go to Step 8 |
8 |
Does the voltage measure near the specified value? | 5.0 V | Go to Step 10 | Go to Step 12 |
9 | Inspect for poor connections at the harness connector of the 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 17 | Go to Step 13 |
10 | Inspect for poor connections at the harness connector of the 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 17 | Go to Step 14 |
11 | Inspect for poor connections at the harness connector of 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 17 | Go to Step 15 |
12 | Inspect for poor connections at the harness connector of the IPM. 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 17 | Go to Step 16 |
13 | Replace the blower motor. Refer to Blower Motor Replacement in Heating, Ventilation and Air Conditioning. Did you complete the replacement? | -- | Go to Step 17 | -- |
14 | Replace the blower motor control processor. Refer to Blower Motor Control Processor Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
15 | Replace the 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 17 | -- |
16 | Replace the IPM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 17 | -- |
17 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2 |
