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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1471 (Engine Control System - Diagnosis - 4.2L (DTC P0013 To DTC P0138)) >> Diagnosis Information & Procedures >> DTC P0120 >> Conditions for Clearing the MIL/DTC

Conditions for Clearing the MIL/DTC

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
DTC P0120

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 Are DTCs P0122 and P0123 also set? - Go to Diagnostic Trouble Code (DTC) List Go to Step 3 
3
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the TP sensor voltage with the accelerator pedal in the rest position with a scan tool.
Does the scan tool indicate voltage less than the first value or greater than the second value?		 0.27 V
4.67 V		 Go to Step 6  Go to Step 4 
4 Is DTC P2135 also set? - Go to Diagnostic Trouble Code (DTC) List Go to Step 5 
5
  1. Observe the Freeze Frame/Failure Records data 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 Intermittent Conditions
6
  1. Turn OFF the ignition.
  2. Disconnect the throttle body harness connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the TP sensor 1 voltage parameter with a scan tool.
Does the scan tool indicate voltage at the specified value?		 0 V Go to Step 7  Go to Step 12 
7
  1. Connect a fused jumper wire between the throttle position (TP) sensor 5-volt reference circuit and the TP sensor 1 signal circuit at the throttle body harness connector.
  2. Observe the TP sensor 1 voltage parameter with a scan tool.
Does the scan tool indicate the TP sensor 1 voltage at the specified value?		 5 V Go to Step 8  Go to Step 9 
8 Probe the TP sensor low reference circuit with a test lamp connected to B+.
Does the test lamp illuminate?		 - Go to Step 18  Go to Step 14 
9 Measure the voltage of the TP sensor 1 5-volt reference circuit with a DMM.
Does the DMM indicate voltage at the specified value?		 5 V Go to Step 11  Go to Step 10 
10 Does the DMM indicate voltage less than the specified value on the TP sensor 1 5-volt reference circuit? 5 V Go to Step 15  Go to Step 17 
11 Test the TP sensor 1 signal circuit 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 22  Go to Step 13 
12 Test the TP sensor 1 signal circuit 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 22  Go to Step 20 
13 Test the TP sensor 1 signal circuit 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 22  Go to Step 20 
14 Test the TP sensor 1 low reference circuit 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 22  Go to Step 20 
15 Test the TP sensor 1 5-volt reference circuit 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 22  Go to Step 16 
16 Test the TP sensor 1 5-volt reference circuit 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 22  Go to Step 20 
17 Test the TP sensor 1 5-volt reference circuit 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 22  -
18 Test for an intermittent and for a poor connection at the throttle body. Refer to Testing for Intermittent Conditions and Poor Connections andConnector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 22  Go to Step 19 
19 Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement .
Did you complete the replacement?		 - Go to Step 22  -
20 Test for an intermittent and for a poor connection at the powertrain control module (PCM). 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 22  Go to Step 21 
21 Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?		 - Go to Step 22  -
22
  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 23 
23 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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