FixVault
Home › Chevrolet › 2004 › Optra Base, Automatic › Repair and Diagnosis › Engine Performance › System › Engine Controls - 1.8L (L79) - DTC P0106 To DTC P0300 › DTC P0108 › Test Description

Test Description

  1. 4:  This step determines if there is a short to voltage or an open condition in the circuits.
  1. 9:  This step determines if the circuit has a short to voltage. A short to voltage can cause more than one DTC to set.
Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics (European Emissions)  or  Engine Controls Schematics (Non European Emissions) 
Connector End View Reference:  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
  1. Start the engine.
  2. Observe the DTC Information with a scan tool.
Did DTC P0108 fail 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.
Does the DTC fail this ignition?		 - Go to Step 4  Go to Intermittent Conditions
4 
  1. Turn OFF the ignition.
  2. Disconnect the manifold absolute pressure (MAP) sensor electrical connector.
  3. Turn ON the ignition, with the engine OFF.
Does the scan tool indicate that the MAP sensor parameter is less than the specified value?		 12 kPa Go to Step 5  Go to Step 7 
5 Measure the voltage from the 5-volt reference circuit of the MAP sensor to a good ground.
Does the voltage measure more than the specified value?		 5.2 V Go to Step 9  Go to Step 6 
6 Measure the resistance between the low reference circuit of the MAP sensor and the engine control module (ECM) housing with a DMM.
Is the resistance less than the specified value?		 2 Ω Go to Step 10  Go to Step 8 
7 Test the signal circuit of 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 14  Go to Step 11 
8
IMPORTANT: The ECM and MAP sensor may be damaged if the circuit is shorted to battery positive voltage.
Test the low reference circuit of the MAP sensor for the following conditions:
  • A short to voltage
  • An open
  • 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 
9 
IMPORTANT: The 5-volt reference circuits are internally and externally connected at the controller. Other sensors that share the 5-volt reference circuit 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 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 14  Go to Step 11 
10 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 14  Go to Step 12 
11 Test for an intermittent and for a poor connection 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 MAP sensor. Refer to Manifold Absolute Pressure Sensor Replacement .
Did you complete the replacement?		 - Go to Step 14  -
13 Replace the ECM. Refer to Engine Control Module 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
About FixVault