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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1382 (Engine Control System Diagnosis (DTC P0010 To DTC P0128) -- 1.8L (LNK)) >> Diagnosis >> DTC P0123 >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 Pontiac Vibe. 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. 1:  The Diagnostic System Check - Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
  2. 2:  This step determines if DTC P0123 is the result of a hard failure or an intermittent condition.
DTC P0123

Step Action Values Yes No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Powertrain Control Module (PCM) 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  With the throttle closed, select the TP sensor parameter on the scan tool.
Is the TP sensor percentage within the specified value?		 7-11% Go to Step 3  Go to Step 4 
3
  1. Perform the scan tool Clear DTC Information function.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Freeze Frame conditions as specified.
Does DTC P0123 set?		 - Go to Step 4  Go to Diagnostic Aids
4 Is a DTC P0118 or P0453 also set? - Go to Step 7  Go to Step 5 
5
  1. Disconnect the TP sensor electrical connector.
  2. Connect a test lamp to B+ and the ground circuit of the TP sensor.
Did the test lamp illuminate?		 - Go to Step 6  Go to Step 8 
6
  1. Test for a short to voltage in the TP sensor input circuit.
  2. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.
Did you find and repair a condition?		 - Go to Step 13  Go to Step 12 
7
  1. Test for an open in the TP sensor ground circuit between SP108 and the PCM.
  2. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.
Did you find and correct a condition?		 - Go to Step 13  Go to Step 11 
8
  1. Test for an open in the TP sensor ground circuit between SP108 and the TP sensor.
  2. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.
Did you find and correct a condition?		 - Go to Step 13  Go to Step 9 
9
  1. Test for an intermittent or a poor electrical connection at the TP sensor. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. Repair the circuit as necessary. Refer to Wiring Repairs and Connector Repairs in Wiring Systems.
Did you find and correct a condition?		 - Go to Step 13  Go to Step 10 
10 Replace the TP sensor. Refer to Throttle Position (TP) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 13  -
11
  1. Test for an intermittent or a poor electrical connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. Repair the circuit as necessary. Refer to Wiring Repairs and Connector Repairs in Wiring Systems.
Did you find and correct a condition?		 - Go to Step 13  Go to Step 12 
12 Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?		 - Go to Step 13  -
13
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC run and pass?		 - Go to Step 14  Go to Step 2 
14 With a scan tool, observe the stored information, Capture Info.
Does the scan tool display any DTCs that you have not diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List System OK
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