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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1165 (Engine Controls Diagnosis - 3.6L (Ly7) (DTC P0135 To DTC P0420)) >> Diagnostic Trouble Codes >> DTC P0343, P0348, P0368, or P0393 >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 Buick Rendezvous. 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. 2:  This step determines that the condition is present.
  2. 4:  This step tests the signal circuit of the CMP sensor. This circuit is pulled-up to about 5 volts.
  3. 5:  The ECM produces a measurable steady-state amperage that provides the 5-volt reference to the CMP sensors. If the amperage on the 5-volt reference circuit is less than the specified value, test for a condition in the 5-volt reference circuit.
  4. 6:  This step tests for high resistance in the low reference circuit of the CMP sensors. The ECM must be completely powered down to obtain an accurate resistance reading. It may take up to 30 minutes for the ECM to power down after the ignition key is removed. Removal of the ECM/TCM fuse allows the ECM to power down completely.
DTC P0343, P0348, P0368, or P0393

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: If DTC P0118 also sets, refer to DTC P0118 .
  1. Turn ON the ignition, with the engine OFF.
  2. Clear the diagnostic trouble codes (DTCs) with a scan tool.
  3. Start the engine.
  4. Observe the DTC information with a scan tool.
Does the scan tool indicate that DTC P0343, P0348, P0368, or P0393 failed this ignition?		 - 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 
  1. Turn OFF the ignition.
  2. Disconnect the appropriate camshaft position (CMP) sensor connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage between the signal circuit of the CMP sensor and the engine control module (ECM) housing with a DMM.
Is the voltage within the specified range?		 4.5-5.5 V Go to Step 5  Go to Step 7 
5 
  1. Set up a DMM to test amperage on the 400 mA scale.
  2. Measure the amperage from the 5-volt reference circuit of the CMP sensor to the ECM housing.
Is the amperage more than the specified value?		 80 mA Go to Step 6  Go to Step 8 
6 
  1. Turn OFF the ignition.
  2. Remove the ECM/TCM fuse from the underhood electrical center.
    3. NOTE: Do NOT use a test lamp to test the continuity of the circuit. Damage to the control module may occur due to excessive current draw.
  3. Measure the resistance between the low reference circuit of the CMP sensor and the ECM housing with a DMM.
Is the resistance less than the specified value?		 5 ohm Go to Step 10  Go to Step 9 
7 Test the signal circuit of the CMP sensor for an open or 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 14  Go to Step 11 
8
IMPORTANT: This 5-volt reference circuit is shared with the other CMP sensors. The 5-volt reference circuits of the CMP sensors are connected externally of the controller. The other CMP sensors may also have DTCs set. Disconnecting a sensor on the shared 5-volt reference circuit may isolate a shorted sensor. Review the electrical schematic and diagnose the shared circuits and sensors.
Test the 5-volt reference circuit of the CMP sensor for an open or 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 14  Go to Step 11 
9
IMPORTANT: The low reference circuits are shared with other components. The low reference circuits are connected internally and externally of the controller. Other sensors that share the low reference circuit may also have DTCs set. Review the electrical schematic and diagnose the shared circuits and sensors.
Test the low reference circuit of the CMP sensors 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 14  Go to Step 11 
10 Test for shorted terminals and for poor connections at the CMP sensor. 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 
11 Test for shorted terminals and for poor connections 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 
12 Replace the CMP sensor. Refer to one of the following procedures:
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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