How To Test The MAP Sensor (1996-1999 2.5L OHV Dodge Dakota)

The MAP sensor, on the 1996, 1997, 1998, and 1999 2.5L OHV Dodge Dakota, can be easily tested with a multimeter and a vacuum pump.

In this tutorial, I'll show you how to bench test the manifold absolute pressure (MAP) sensor so that you can find out if it's defective or not.

With your test results, you'll be able to diagnose the following MAP sensor trouble codes P0107 and P0108.

You can find this tutorial in Spanish here: Cómo Probar El Sensor MAP (1996-1999 2.5L OHV Dodge Dakota) (at: autotecnico-online.com).

NOTE: The test for the 1994-1995 2.5L SOHC Dodge Dakota can be found here: How To Test The MAP Sensor (1994-1995 2.5L SOHC Dodge Dakota).

Symptoms Of A Bad MAP Sensor

Your Dodge Dakota uses 3 inputs to calculate how much air the engine is breathing. These are intake manifold pressure, intake air temperature and engine RPM. These inputs are provided, respectively, by the MAP sensor, the intake air temp (IAT) sensor, and the crankshaft position sensor.

Since the MAP sensor is a mission-critical component of the engine management system, when it fails, your Dodge Dakota is gonna' feel it.

Here are some specific symptoms you'll see when the manifold absolute pressure (MAP) sensor fails:

• The check engine light is lit with one of the following trouble codes:
  • P0107: MAP Sensor Voltage Too Low.
  • P0108: MAP Sensor Voltage Too High.
• Engine is difficult to start.
• Rough engine idle.
• Black smoke coming out of the tail pipe when engine is running.
• Lack of power when accelerating the engine or vehicle down the road.

OBD II Trouble Code P0107 And P0108

When the manifold absolute pressure (MAP) sensor fails on your 1997-2003 2.5L Dodge Dakota, you're gonna' see one of two trouble codes lighting up the check engine light. These are:

• P0107: MAP Sensor Voltage Too Low
• P0108: MAP Sensor Voltage Too High.

Knowing what causes each trouble code to pop up will help you troubleshoot and resolve the MAP sensor trouble code. With this in mind, here's a brief explanation of what these trouble codes mean for your Dodge Dakota.

Trouble Code P0107: MAP Sensor Voltage Too Low: This trouble code is telling you that your Dodge Dakota's fuel injection computer is seeing a MAP sensor voltage lower than a predetermined voltage (in its program) when the engine starts.

Trouble code P0107 usually sets when the MAP sensor fails and reports a voltage that is between 2.3 to 0.2 Volts DC with the KEY ON ENGINE OFF (instead of a voltage of about 4.5 Volts) or a voltage of 0.2 Volts DC with the KEY ON ENGINE RUNNING for a period of about 2 seconds.

Trouble Code P0108: MAP Sensor Voltage Too High: This trouble code is telling you that your Dodge Dakota's fuel injection computer is seeing a MAP sensor voltage greater than a predetermined voltage (in its program) when the engine starts and runs.

Trouble code P0108 usually sets when the MAP sensor fails and reports a voltage that is at or above 4.5 Volts DC with the KEY ON ENGINE RUNNING longer than 2 seconds.

The P0108 trouble code can also be set when the insulation on the MAP sensor wires starts to fall off and the wires short to each other. This causes the fuel injection computer to see the 5 Volts from the MAP sensor's power feed on the MAP signal wire.

MAP Sensor Circuit Descriptions

The MAP sensor is a 3 wire type sensor. This means that it has a power wire, a Ground wire and a signal wire. The table below has a brief description of each:

MAP Sensor Circuits 1997-1999 2.5L Dodge Dakota
Terminal	Wire	Description
1	BLK/LT BLU	Ground
2	DK GRN/RED	MAP Signal
3	VIO/WHT	5 Volts DC

Where To Buy The MAP Sensor And Save

The MAP sensor isn't an expensive engine management component, but it never hurts to save a few bucks and so with that in mind I think that the following links will help you to comparison shop for it and maybe even save a few bucks:

NOTE: If you're not sure if the above MAP sensor fit your particular 2.5L Dodge Dakota don't worry, once you get to the site, they'll make sure the sensor is the right one, if not, they'll find you the right one.

TEST 1: MAP Sensor Voltage Signal Performance Test

In this very first test, we're gonna' check the performance of the MAP sensor with a multimeter and a vacuum pump.

If you don't have a vacuum pump, don't sweat it. You can apply vacuum to the MAP sensor using a vacuum hose and the good ole' lungs.

To successfully diagnose the MAP sensor, you need to keep in mind is that as you apply vacuum to the MAP sensor its signal voltage should decrease. When you let go of the vacuum, this voltage should shoot back up to its original value.

You'll need a multimeter for this test, if you don't have a multimeter and need to buy one, check out my recommendations here: Buying A Digital Multimeter For Automotive Diagnostic Testing.

IMPORTANT: The MAP sensor needs to stay connected to its electrical connector for this test to work. You'll need to use a back-probe or a wire-piercing probe to measure the MAP signal voltage. To see what a wire-piercing probe looks like, go here: Wire Piercing Probe.

Let's get started:

1. 1

   Connect your vacuum pump to the MAP sensor's vacuum inlet port. Reconnect the MAP sensor to its connector if you disconnected it.

2. 2

   Set your multimeter's selector to Volts DC mode and with the red test lead, probe the DK GRN/RED wire of the MAP sensor's connector.
   
   Remember, the MAP sensor must remain connected to its 3 wire connector.

3. 3

   Ground the black multimeter test lead directly on the battery negative (-) terminal.

4. 4

   When everything is ready, turn the Key on but don't start the engine. This will power up the MAP sensor and you should see a reading of 4.5 to 4.7 Volts DC on your multimeter.
   
   Now, apply vacuum to the MAP sensor with the vacuum pump (or your mouth). The voltage signal value should decrease.
   
   Release the vacuum. Once released, your multimeter should show the original voltage value.
   
   Repeat this test step several times making sure that each time the voltage decreases/increases as you apply/release vacuum.

Let's find out what your test results mean:

CASE 1: The MAP voltage signal decreased and increased as you applied and released vacuum. This is the correct and expected test result and lets you know that the MAP sensor on your 2.5L OHV Dodge Dakota is not defective.

CASE 2: The MAP voltage signal DID NOT increase (and/or decrease) as you applied and released vacuum. In most cases, this test result is enough to confirm that the MAP sensor is defective and that it needs to be replaced.

To be sure the MAP sensor is defective, you need to make sure it's getting power and Ground. For the next MAP sensor diagnostic tests, go to: TEST 2: Verifying MAP Sensor Has 5 Volts and Ground.

CASE 3: The multimeter DID NOT register any voltage. In most cases, this test result is enough to confirm that the MAP sensor is defective and that it needs to be replaced.

To be sure the MAP sensor is defective, you need to make sure it's getting power and Ground. For the next MAP sensor diagnostic tests, go to: TEST 2: Verifying MAP Sensor Has 5 Volts and Ground.