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Test Description

WARNING: This page is about a different car, the 2004 Buick Regal. 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. 2:  This step tests for improper throttle position (TP) sensor operation.
DTC P0108

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Engine Controls Connector End Views  or  Powertrain Control Module (PCM) 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 
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the TP sensor parameter with the scan tool.
  3. Depress the accelerator pedal slowly until the throttle is in the wide open position.
  4. Release the accelerator pedal slowly until the throttle is returned to the closed position.
  5. Repeat this procedure several times.
Does the TP sensor parameter increase steadily to more than the first specified value, then decrease steadily returning to less than the second specified value?		 98%
1%		 Go to Step 3  Go to DTC P0121 
3
  1. Start the engine.
  2. Observe the MAP sensor parameter with the scan tool.
Is the voltage more than the specified value?		 4.2 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 5  Go to Intermittent Conditions
5 Inspect the manifold absolute pressure (MAP) sensor vacuum source for the following conditions:
  • Leaks
  • Restrictions
  • Faulty Connections

Did you find and correct the condition?		 - Go to Step 16  Go to Step 6 
6 Monitor the Diagnostic Trouble Code (DTC) Information with the scan tool.
Is DTC P0641 also set?		 - Go to Step 10  Go to Step 7 
7 Test for an intermittent and for a poor connection at the MAP 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 16  Go to Step 8 
8
  1. Turn OFF the ignition.
  2. Disconnect the MAP sensor electrical connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the MAP sensor parameter with the scan tool.
Is the voltage less than the specified value?		 0.1 V Go to Step 9  Go to Step 11 
9
  1. Turn OFF the ignition.
  2. Disconnect the engine coolant temperature (ECT) sensor.
  3. Connect a jumper wire between each of the terminals in the MAP sensor harness connector and the corresponding terminal at the MAP sensor. Refer to Using Connector Test Adapters in Wiring Systems.
  4. Turn ON the ignition, with the engine OFF.
  5. Measure the voltage from the low reference circuit of the MAP sensor at the jumper wire terminal to a good ground with a DMM. Refer to Measuring Voltage Drop in Wiring Systems.
Is the voltage more than the specified value?		 0.2 V Go to Step 12  Go to Step 14 
10
  1. Turn OFF the ignition.
  2. Disconnect the MAP sensor electrical connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the MAP sensor parameter with the scan tool.
Is the voltage less than the specified value?		 0.1 V Go to DTC P0641 Go to Step 11 
11
IMPORTANT: Disconnecting the powertrain control module (PCM) may eliminate the short during testing.
IMPORTANT: The MAP sensor may have been damaged if the circuit was shorted to a voltage source.
Test the MAP sensor signal circuit between the PCM and the MAP sensor 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 16  Go to Step 15 
12 Test the low reference circuit between the PCM and the MAP sensor for high resistance or an open. Refer to Circuit Testing andWiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 16  Go to Step 13 
13 Test for an intermittent and for a poor connection at the 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 16  Go to Step 15 
14 Replace the MAP sensor. Refer to Manifold Absolute Pressure (MAP) Sensor Replacement (L36)Manifold Absolute Pressure (MAP) Sensor Replacement (L67) .
Did you complete the replacement?		 - Go to Step 16  -
15 Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?		 - Go to Step 16  -
16
  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 form the Freeze Frame/Failure Records.
Did the DTC fail this ignition?		 - Go to Step 2  Go to Step 17 
17 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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