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Home >> Cadillac >> 2004 >> CTS Base, 3.2 N >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 21 (Engine Controls - 3.6L - Diagnosis (DTC P0008 - P0151)) >> Diagnosis >> DTC P0030, P0036, P0050, or P0056 >> Test Description

Test Description

WARNING: This page is about a different variant/trim than selected.

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

  1. 4:  If both DTCs are set for either the front sensors or the rear sensors, the ignition voltage circuit to the heaters may be open. The front sensors are fused separately from the rear sensors.
  2. 5:  The engine must be running for the ECM to operate the control circuit.
  3. 6:  The heater control circuit is equipped with a feedback circuit internal to the ECM. This feedback circuit allows the ECM to determine if the heater control circuit is open, shorted to ground, or shorted to a voltage. If the voltage is not within the specified range, there is a condition with the control circuit.
DTC P0030, DTC P0036, DTC P0050, or DTC P0056 - HO2S Heater Control Circuit (Open)

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Engine Control Module (ECM) Connector End Views  or  Engine Controls Connector End Views 
1 Did you perform the Diagnostic System Check-Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls
2
  1. Start the engine.
  2. Allow the engine to idle for at least 30 seconds.
  3. Observe the DTC information with a scan tool.
Does DTC P0030, DTC P0036, DTC P0050, or DTC P0056 set?		 - Go to Step 4  Go to Step 3 
3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?		 - Go to Step 4  Go to Diagnostic Aids
4  Are DTCs P0030 and P0050 set at the same time or are DTCs P0036 and P0056 set at the same time? - Go to Step 11  Go to Step 5 
5 
  1. Turn OFF the ignition.
    2. IMPORTANT: The ignition must be OFF when disconnecting or connecting the heated oxygen sensor (HO2S) electrical connector.
  2. Disconnect the appropriate HO2S.
  3. Connect a test lamp between the ignition voltage circuit of the HO2S and the heater control circuit of the HO2S.
  4. Start the engine.
Does the test lamp illuminate or flash?		 - Go to Step 6  Go to Step 7 
6 
  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage between the heater control circuit of the HO2S and the engine control module (ECM) housing with a DMM.
Is the voltage within the specified range?		 4.6-5.2 V Go to Step 9  Go to Step 10 
7 Connect a test lamp between the ignition 1 voltage circuit of the HO2S and the ECM housing.
Does the test lamp illuminate?		 - Go to Step 8  Go to Step 11 
8
  1. Turn OFF the ignition.
  2. Disconnect the ECM.
  3. Test the heater control circuit between the HO2S and the ECM for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 10 
9 Test for an intermittent and for a poor connection at the HO2S. 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 14  Go to Step 12 
10 Test for an intermittent and for a poor connection at the ECM. 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 14  Go to Step 13 
11
    IMPORTANT: The ignition voltage circuit supplies voltage to other components. Make sure you test all circuits for a short to ground or test all components for being shorted that share the ignition voltage circuit.
  1. Repair the open or the grounded ignition voltage circuit of the HO2S. Refer to Wiring Repairs in Wiring Systems.
  2. Replace the fuse if necessary.
Did you complete the repair?		 - Go to Step 14  -
12 Replace the HO2S. Refer to the appropriate procedure:
Did you complete the replacement?		 - Go to Step 14  -
13 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 14  -
14
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?		 - Go to Step 2  Go to Step 15 
15 Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List System OK
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