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HOMESERVICE MANUALSCHEVROLET2006CHEVY EXPRESS G2500, VAN CARGO, 6.6 2REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 951 (ENGINE CONTROL SYSTEM & FUEL SYSTEM - 4.3L - DTC P0016 TO DTC P0158)DTC P0123TEST DESCRIPTION
2006 Chevrolet Chevy Express G2500, Van Cargo, 6.6 2

Test Description

2006 Chevrolet Chevy Express G2500, Van Cargo, 6.6 2SECTION Test Description
WARNING: This page is about a different car, the 2007 GMC Savana and 2007 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.

The number below refers to the step number on the diagnostic table.

  1. 7:  Each terminal in the connector must be jumpered to its respective mate in the sensor. This allows the sensor to operate and permits access to the low reference circuit for the voltage drop measurement.
DTC P0123

Step Action Values Yes No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2
  1. Start the engine.
  2. Monitor the DTC information with the scan tool.
Is DTC P0641 also set?		 - Go to DTC P0641 Go to Step 3 
3 Observe the TP sensor parameter with the scan tool.
Is the voltage more than the specified value?		 4.9 V Go to Step 5  Go to Step 4 
4
  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 6  Go to Step 5 
5 Test for an intermittent and for a poor connection at the throttle position (TP) sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 13  Go to Step 6 
6
  1. Turn OFF the ignition.
  2. Disconnect the TP sensor electrical connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the TP Sensor parameter with the scan tool.
Is the voltage less than the specified value?		 0.1 V Go to Step 7  Go to Step 8 
7 
  1. Connect a jumper wire between each of the terminals in the TP sensor harness connector and the corresponding terminal at the TP sensor. Refer to Using Connector Test Adapters .
  2. Measure the voltage from the low reference circuit of the TP sensor at the jumper wire terminal to a good ground with a DMM. Refer to Measuring Voltage Drop .
Is the voltage more than the specified value?		 0.2 V Go to Step 9  Go to Step 11 
8 Test the TP sensor signal circuit between the powertrain control module (PCM) and the TP sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 13  Go to Step 12 
9 Test the low reference circuit between the PCM and the TP sensor for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 13  Go to Step 10 
10 Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 13  Go to Step 12 
11 Replace the TP sensor. Refer to Throttle Position Sensor Replacement .
Did you complete the replacement?		 - Go to Step 13  -
12 Replace the PCM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?		 - Go to Step 13  -
13
  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 14 
14 Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List - Vehicle System OK
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.