For 1990-2009 cars

### Circuit Description

Power Transistor is to control blower motor and input the signal into a HVAC control module.

### DTC Descriptors

This diagnostic procedure supports the following DTC :

DTC B0193 Blower Motor Speed

### Conditions for Running the DTC

Ignition is ON.

### Conditions for Setting the DTC

• | The blower motor operating voltage is less than 5.0 V, actual blower motor feedback voltage, than 9.0 V of blower motor operating voltage.

• | The blower motor operating voltage is greater than 9.0 V, actual blower motor feedback voltage, than 5.0 V of blower motor operating voltage.

• | The HVAC control module detects that the blower motor control circuit is open.

### Action Taken When the DTC Sets

The inside air temperature sensor value setting is 25 degrees.

### Conditions for Clearing the DTC

• | The DTC will become history if the HVAC control module no longer detects a fault.

• | Ignition is ON or OFF.

• | The DTC can be cleared with a scan tool.

### Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

1. Tests voltage of the blower motor level between low and high level and increase the voltage all level at 0.5 V.

Level | Voltage
--- | ---
0 | 0
1 | 4.0
2 | 4.5
3 | 5.0
4 | 5.5
5 | 6.0
6 | 6.5
7 | 7.0
8 | 7.5
9 | 8.0
10 | 8.5
11 | 9.0
12 | 9.5
13 | 10.0
14 | 10.5
15 | Max

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Test the appropriate power transistor assembly signal circuit of the power transistor assembly for a short to ground. Did you find and correct the condition? | -- | Go to Step 8 | Go to Step 3
3 | Test the appropriate signal circuit of the power transistor assembly for a short to voltage, a high resistance, or an open. did you find and correct the condition? | -- | Go to Step 8 | Go to Step 4
4 | Test the voltage power transistor and change each level. Did you find and correct the condition? | -- | Go to Step 8 | Go to Step 5
5 | Inspect for poor connections at the harness connector of the power transistor assembly. Did you find and correct the condition? | -- | Go to Step 8 | Go to Step 5
6 | Inspect for poor connections at the harness connector of the HVAC module. Did you find and correct the condition? | -- | Go to Step 8 | Go to Step 7
7 | Replace the power transistor assembly. Did you complete the replacement? | -- | Go to Step 8 | --
8 |

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK