Testing the MAP sensor is a piece of cake on the 1998-2003 2.2L Chevrolet S10 pickup (GMC Sonoma).
This tutorial will walk you through the entire testing process step by step. You'll quickly and easily determine if the manifold absolute pressure (MAP) sensor is good or bad.
No expensive diagnostic equipment is needed since you only need a multimeter and a vacuum pump.
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar El Sensor MAP (1998-2003 2.2L Chevrolet S10, GMC Sonoma) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicles:
- 2.2L Chevrolet S10 Pickup: 1998, 1999, 2000, 2001, 2002, 2003.
- 2.2L GMC Sonoma: 1998, 1999, 2000, 2001, 2002, 2003.
- 2.2L Isuzu Hombre: 1998, 1999, 2000.
Symptoms Of A Bad MAP Sensor
The MAP sensor is tasked with measuring intake manifold vacuum as the engine runs. This measurement is then sent to the fuel injection computer.
The fuel injection computer then uses this information to calculate the engine's load and inject the correct amount of fuel the engine needs to run optimally.
The MAP sensor is a crucial component of the engine management system, as such when it fails engine performance will suffer and the computer will set one of the following diagnostic trouble codes:
- P0106: MAP Sensor System Performance.
- P0107: MAP Sensor Circuit Low Voltage.
- P0108: MAP Sensor Circuit High Voltage.
You'll also see one or more of the following symptoms:
- The engine won't start.
- The engine takes a long time to start (extended cranking time).
- Black smoke coming out of the tailpipe.
- Bad gas mileage.
- The engine idles rough when running.
- A lack of power when under load.
Where To Buy The MAP Sensor And Save
The MAP sensor is a very common engine management system component that you can find at any auto parts store.
If you'd like to save a few bucks on its purchase, the following links will help you to comparison shop for the MAP sensor of known automotive brands (no knockoff parts):
Not sure if the MAP sensor fits your vehicle? Don't worry. Once you get to the site, they'll make sure it fits by asking you the specifics of your vehicle. If it doesn't fit, they'll find you the right MAP sensor.
MAP Sensor Circuit Descriptions
The manifold absolute pressure sensor has three wires coming out of its connector.
Each wire has a specific function and in the following table, you'll find a description of each:
| Wire | Color | Description |
|---|---|---|
| A | Black with white stripe (BLK/WHT) | Ground |
| B | Light green (LT GRN) | MAP signal |
| C | Grey (GRY) | 5 Volts |
TEST 1: Testing The MAP Sensor Signal
To successfully diagnose the MAP sensor as good or bad, it's important to know that:
- The MAP sensor's output voltage decreases as vacuum is applied to it.
- The MAP sensor's output voltage increases as vacuum is released.
If the MAP sensor has failed, it'll generally stay stuck, producing a single voltage value as you apply/release vacuum to it.
If your test results confirm that the MAP sensor's output voltage value is stuck in one value, we'll move on to TEST 2 and make sure that the sensor is receiving 5 Volts.
NOTE: If you don't have a vacuum pump, don't worry. You can use your mouth to apply vacuum to the MAP sensor.
IMPORTANT: The MAP sensor must remain connected to its electrical connector to read the voltage within its signal wire. You'll need to use a back probe on the connector or a wire piercing probe on the wire. You can see an example of this tool here: Wire Piercing Probe.
OK, let's get started:
- 1
Remove the MAP sensor from its place on the intake manifold.
- 2
If you had to disconnect the MAP sensor from its electrical connector to remove it, reconnect it to the connector now.
- 3
Connect your vacuum pump to the MAP sensor's vacuum inlet.
You'll need to use a piece of vacuum hose to connect the vacuum pump to the MAP sensor. - 4
Place your multimeter in Volts DC mode.
- 5
Connect the red multimeter probe to the wire that connects to the terminal labeled with the letter B (in the image above).
This wire should be the light green (LT GRN) wire of the connector.
IMPORTANT: The MAP sensor must remain connected to its 3-wire connector. - 6
Connect the black multimeter test lead directly to the battery negative (-) terminal.
- 7
Turn the key ON but don't start the engine.
- 8
At this point your multimeter should register a value around 4.5 Volts DC.
- 9
Now, pump the vacuum pump to apply vacuum to the MAP sensor. The voltage should decrease.
- 10
Release the vacuum you applied to the MAP sensor. The voltage should increase.
OK, let's take a look at what your test results mean:
CASE 1: The MAP voltage signal decreased/increased as you applied/released vacuum to the sensor. This is the correct result and confirms that the MAP sensor is functioning correctly.
If a MAP sensor diagnostic trouble code keeps illuminating the check engine light, you can conclude the MAP sensor itself is not the cause. For more info, take a look at the section: MAP Sensor Code Won't Go Away.
CASE 2: The MAP voltage signal DID NOT increase/decrease as you applied/released vacuum. This test result usually indicates that the MAP sensor is bad.
Before replacing the MAP sensor, you need to make sure that it's getting power and Ground. Go to the next test: MAP TEST 2: Making Sure The MAP Sensor Is Getting 5 Volts.
CASE 3: Your multimeter registered 0 Volts. This test result generally tells you that the MAP sensor is bad.
Before replacing the MAP sensor, you need to make sure that it's getting power and Ground. Go to the next test: MAP TEST 2: Making Sure The MAP Sensor Is Getting 5 Volts.
