Circuit Description
The manifold absolute pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on the engine load. The MAP sensor has the following circuits:
| • | 5-volt reference circuit |
| • | Low reference circuit |
| • | MAP sensor signal circuit |
The powertrain control module (PCM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The PCM also provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the MAP sensor signal circuit which is relative to the pressure changes in the manifold. The PCM should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The PCM should detect a high signal voltage at a high MAP, such as the ignition is ON, with the engine OFF, or at a wide open throttle (WOT). The MAP sensor is also used in order to determine the barometric pressure (BARO). This occurs when the ignition switch is turned ON, with the engine OFF. The BARO reading may also be updated whenever the engine is operated at WOT. The PCM monitors the MAP sensor signal for voltage outside of the normal range.
If the PCM detects a MAP sensor signal voltage that is excessively high, DTC P0108 sets. If the PCM detects a MAP sensor signal voltage that is excessively low, DTC P0107 sets
Test Description
The number below refers to the step number on the diagnostic table.
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-Engine Controls? | -- | Go to Step 2 | |||||||||
2 | Inspect for the following conditions:
Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 3 | ||||||||
3 |
Important: The vehicle used for the comparison is not limited to the same type of vehicle as is being serviced. A vehicle known to provide an accurate reading is acceptable. Do you have access to another vehicle in which the MAP sensor pressure can be observed with a scan tool? | -- | Go to Step 4 | Go to Step 5 | ||||||||
Is the difference between the values less than the specified value? | 3 kPa | Go to Step 6 | Go to Step 10 | |||||||||
5 |
Important: The Altitude vs. Barometric Pressure table indicates a pressure range for a given altitude under normal weather conditions. Weather conditions consisting of very low or very high pressure and/or very low or very high temperature may cause a reading to be slightly out of range.
Does the MAP sensor indicate the correct barometric pressure? | -- | Go to Step 6 | Go to Step 10 | ||||||||
6 |
Does the MAP sensor pressure change? | -- | Go to Step 7 | Go to Step 10 | ||||||||
7 |
Is the decrease in MAP sensor pressure consistent? | -- | Go to Step 8 | Go to Step 10 | ||||||||
8 | Apply vacuum with the hand vacuum pump until 20 inch Hg is reached. Is the MAP sensor pressure less than the specified value? | 34 kPa | Go to Step 9 | Go to Step 10 | ||||||||
9 | Disconnect the hand vacuum pump from the MAP sensor. Does the MAP sensor pressure return to the value observed in step 4 or 5? | -- | System OK | Go to Step 22 | ||||||||
10 |
Is the voltage less than the specified value? | 0.1 V | Go to Step 11 | Go to Step 15 | ||||||||
11 | Measure the voltage from the 5 volt reference circuit of the MAP sensor to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems. Is the voltage more than the specified value? | 5.2 V | Go to Step 16 | Go to Step 12 | ||||||||
12 | Probe the 5-volt reference circuit of the MAP sensor with a test lamp that is connected to a good ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Is the test lamp OFF? | -- | Go to Step 17 | Go to Step 13 | ||||||||
13 |
Is the voltage more than the specified value? | 4.9 V | Go to Step 14 | Go to Step 18 | ||||||||
14 |
Is the voltage more than the specified value? | 0.2 V | Go to Step 19 | Go to Step 20 | ||||||||
15 |
Important: Disconnecting the 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 24 | Go to Step 23 | ||||||||
16 |
Important: Disconnecting the 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 all the branches of the 5-volt reference circuit that are shared with 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 24 | Go to Step 23 | ||||||||
17 | Test the 5-volt reference circuit between the PCM and the MAP sensor for an open or for a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 21 | ||||||||
18 | Test the MAP sensor signal circuit between the PCM and the MAP sensor for the following:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 21 | ||||||||
19 | Test the low reference circuit between the PCM and the MAP sensor for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 21 | ||||||||
20 | 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 24 | Go to Step 22 | ||||||||
21 | 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 24 | Go to Step 23 | ||||||||
22 | Replace the MAP sensor. Refer to Manifold Absolute Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 24 | -- | ||||||||
23 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 24 | -- | ||||||||
24 |
Did you correct the condition? | System OK | Go to Step 2 | |||||||||
