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Home >> Cadillac >> 2004 >> CTS Base, 3.2 N >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 24 (Engine Controls - 3.6L - Diagnosis (DTC P2188 - P2636)) >> Engine Controls Diagnosis >> DTC P2237 or P2240 >> 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. 2:  This step determines if the condition exists. The HO2S lambda parameter should react immediately to the changes in throttle position when performing this test.
  2. 4:  This step determines if there is a condition with the input pump current and pump current circuit. Connecting a jumper wire between the reference voltage and the low reference circuits causes the ECM to command the pumping current and the input pumping current circuits.
DTC P2237 or P2240

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 
IMPORTANT: DTC P2237 is for bank 1 sensor 1. DTC P2240 is for bank 2 sensor 1.
  1. Start the engine.
  2. Allow the engine to reach operating temperature.
  3. Cycle the throttle from idle to wide open throttle 3 times within 5 seconds.
  4. Observe the affected HO2S lambda value with a scan tool.
Does the affected HO2S lambda value react immediately to the above action?		 - Go to Step 3  Go to Step 4 
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 
  1. Turn OFF the ignition.
  2. Disconnect the appropriate heated oxygen sensor (HO2S).
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a 3-amp fused jumper wire between the reference voltage circuit and the low reference circuit of the HO2S.
  5. Measure the voltage between the input pump current circuit and a good ground.
Is the voltage more than the specified value?		 1.0 V Go to Step 6  Go to Step 5 
5 Test the input pump current and pump current circuit of the HO2S for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 10  Go to Step 7 
6 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 10  Go to Step 8 
7 Test for an intermittent and for a poor connection at the engine control module (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 10  Go to Step 9 
8 Replace the HO2S. Refer to the appropriate procedure:
Did you complete the replacement?		 - Go to Step 10  -
9 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 10  -
10
  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 11 
11 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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