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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 94 (HVAC Systems - Automatic) >> Diagnostic Information and Procedures >> DTC B0229, B0414, B0424, B3761, or B3770 >> Test Description

Test Description

WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 3:  Tests for the proper operation of the circuit in the high voltage range. If the jumper fuse opens when you perform this test, the circuit is shorted to ground.
  2. 7:  Tests for the proper operation of the circuit in the high voltage range. If the jumper fuse opens when you perform this test, the circuit is shorted to ground.
  3. 8:  Tests for a short to voltage in the 5-volt reference circuit.
  4. 9:  Tests for a high resistance or for an open in the low reference circuit.
  5. 10:  This step tests for an open on the low reference circuit that is common to all of the actuators. Choose the easiest HVAC door actuator that set a DTC to start the diagnosis.
  6. 11:  Disconnecting each actuator, one at a time, isolates the disconnected actuators signal circuit from the 5 volt reference circuit that is common to all the actuators.
DTC B0229, B0414, B0424, B3761, or B3770

Step Action Values Yes No
Schematic Reference: HVAC Schematics 
Connector End View Reference:  HVAC Connector End Views  
1 Did you perform the HVAC Diagnostic System Check? - Go to Step 2  Go to Diagnostic System Check - HVAC Systems - Automatic 
2 Is DTC B1375 set as a current DTC? - Go to Diagnostic Trouble Code (DTC) List  Go to Step 3 
3  With a scan tool, observe the Heating and Air Conditioning DTC list.
Does the scan tool indicate that at least 2 of the following DTC B0229, B0414, B0424, B3761 and B3770 are set as current DTC?		 - Go to Step 10  Go to Step 4 
4
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With the scan tool, observe the appropriate Door Actual parameter in the Heating and Air Conditioning data list.
Does the scan tool indicate that the appropriate Door Actual parameter is within the specified range?		 5-250 counts Go to Step 5  Go to Step 6 
5
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the appropriate HVAC door actuator ON and OFF while observing the corresponding Door Actual parameter.
Does the scan tool indicate that the value of the appropriate Door Actual parameter changes?		 - Go to Diagnostic Aids Go to Step 19 
6
  1. Turn OFF the ignition.
  2. Disconnect the appropriate HVAC door actuator.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the appropriate Door Actual parameter.
Does the scan tool indicate that the appropriate Door Actual parameter is less than the specified value?		 5 counts Go to Step 7  Go to Step 17 
7 
  1. Turn OFF the ignition.
  2. Connect a 3-ampere fused jumper between the 5-volt reference circuit and the appropriate door position signal circuit of the HVAC door actuator.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the appropriate Door Actual parameter.
Does the scan tool indicate that the appropriate Door Actual parameter is greater than the specified value?		 230 counts Go to Step 8  Go to Step 15 
8 
  1. Disconnect the fused jumper.
  2. Measure the voltage between the 5-volt reference circuit and the low reference circuit of the HVAC door actuator.
Does the voltage measure less than the specified value?		 5.5 V Go to Step 9  Go to Step 14 
9 
  1. Turn OFF the ignition.
  2. Disconnect the negative battery cable.
  3. Measure the resistance from the low reference circuit of the HVAC door actuator to a good ground.
Does the resistance measure less than the specified value?		 5 Ω Go to Step 22  Go to Step 18 
10 
  1. Disconnect the most accessible affected HVAC door actuator.
  2. Probe the low reference circuit of the HVAC door actuator with a test lamp from battery positive voltage.
Does the test lamp illuminate?		 - Go to Step 11  Go to Step 18 
11 
  1. Turn ON the ignition, with the engine OFF.
  2. With a scan tool, observe the Heating and Air Conditioning DTC list.
  3. While observing DTC list, disconnect and connect the electrical connector for each affected HVAC door actuator.
Did the scan tool indicate that only one DTC was present when a HVAC door actuator was disconnected?		 - Go to Step 13  Go to Step 12 
12 Test the 5-volt reference circuit of the appropriate HVAC door actuator for an open. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 26  Go to Step 23 
13 Test the appropriate door position signal circuit of the HVAC door actuator for a short to ground. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 26  Go to Step 22 
14 Test the 5-volt reference circuit of the appropriate HVAC door actuator for a short to voltage. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 26  Go to Step 23 
15 Test the 5-volt reference circuit of the appropriate HVAC door actuator for a short to ground, for a high resistance, or for an open. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 26  Go to Step 16 
16 Test the appropriate door position signal circuit of the HVAC door actuator for a short to ground, for a high resistance, or for an open. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 26  Go to Step 23 
17 Test the appropriate door position signal circuit of the HVAC door actuator for a short to voltage. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 26  Go to Step 22 
18
  1. Disconnect the HVAC control module.
  2. Test the low reference circuit of the appropriate HVAC door actuator for a high resistance or for an open. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 26  Go to Step 23 
19
  1. Observe the appropriate HVAC door actuator drive shaft.
  2. Backprobe and monitor the voltage from the signal circuit of the air temperature door actuator to a good ground.
  3. Connect a 3 amp fused jumper wire between appropriate door control circuit at the HVAC control module and a good ground.
  4. Disconnect the fused jumper wire.
  5. Connect a 3 amp fused jumper wire between the appropriate door control circuit and the 5 volt reference circuit at the HVAC control module.
Does the drive shaft of the appropriate HVAC door actuator rotate?		 - Go to Step 23  Go to Step 20 
20 Test the door control circuit of the appropriate HVAC door actuator for a short to voltage, for a short to ground, or for an open. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 26  Go to Step 21 
21 Test the ignition 3 voltage circuit of the appropriate HVAC door actuator for an open or a high resistance. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 26  Go to Step 22 
22 Inspect for poor connections at the harness connector of the appropriate HVAC door actuator. Refer to TESTING FOR INTERMITTENT CONDITIONS AND POOR CONNECTIONS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 26  Go to Step 24 
23 Inspect for poor connections at the harness connector of the 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 26  Go to Step 25 
24
IMPORTANT: Perform the calibration procedure for HVAC door actuators.
Replace the HVAC door actuator. Refer to the appropriate replacement procedure:Did you complete the replacement?		 - Go to Step 26  -
25 Replace the HVAC control module. Refer to HVAC Control Module Replacement .
Did you complete the replacement?		 - Go to Step 26  -
26
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle according to the Conditions for Running in the DTC, as specified in the supporting text.
Does the DTC set again?		 - Go to Step 3  System OK
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