In this tutorial, I'm going to explain how to test the manifold absolute pressure (MAP) sensor on the 1993-1996 5.2L V8 Jeep Grand Cherokee.
Testing the MAP sensor simply involves connecting a multimeter to its signal wire and checking to see if it creates a decreasing/increasing voltage signal as vacuum is applied to it.
With your test results you'll be able to find out if the MAP sensor is defective or not in 3 test steps. With three simple test, you'll be able to find out if the MAP sensor on your 5.2L V8 Jeep Grand Cherokee is defective or not.
Contents of this tutorial at a glance:
NOTE: This tutorial applies to the following vehicles since they use the exact same MAP sensor:
- 5.2L V8 Jeep Grand Cherokee: 1993, 1994, 1995
Symptoms Of A Bad MAP Sensor
The fuel injection system, on your 5.2L V8 Jeep Grand Cherokee, is a 'speed-density' fuel system. In plain English, this means that the fuel injection computer needs to know the engine load, the engine RPM, and the temperature of the air entering the engine to calculate the amount of air entering the engine.
Once the fuel injection computer calculates the amount of air entering the engine, it then can inject the correct amount of fuel into the engine.
It's the MAP sensor's job to provide the engine load information the computer needs. This makes the manifold absolute pressure (MAP) sensor a critical component of the engine management system. So, when it fails, engine performance is going to suffer.
On the 1993-1995 OBD I equipped Grand Cherokee, you'll see one of the following trouble codes:
- Code 13: No Change In MAP From Start To Run.
- Code 14: MAP Sensor Voltage Too Low.
- Code 15: MAP Sensor Voltage Too High.
On the 1996 OBD II equipped Grand Cherokee, you'll see one of the following trouble codes:
- P0107: MAP Sensor Voltage Too Low.
- P0108: MAP Sensor Voltage Too High.
You're also going to see one or more of the following symptoms:
- Rough idle.
- ‘Rotten egg’ smell coming from the exhaust.
- Won't pass the state mandated emissions test.
- Bad gas mileage.
- Lack of power, rough idle, or hesitation.
- Engine cranks a long time before starting.
Where To Buy The MAP Sensor And Save
The 1993-1996 5.2L V8 Jeep Grand Cherokee's MAP sensor isn't an expensive engine management component. The following links will help you to comparison shop and hopefully save you a few bucks on its purchase:
NOTE: The above manifold absolute pressure (MAP) sensor fits the following vehicles: 1993-1996 5.2L V8 Jeep Grand Cherokee.
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:
| 1993-1995 5.2L Grand Cherokee | ||
|---|---|---|
| Terminal | Wire | Description |
| 1 | Violet with white stripe (VIO/WHT) | 5 Volts |
| 2 | Red with white stripe (RED/WHT) | MAP Signal |
| 3 | Black with light blue striped (BLK/LT BLU) | Ground |
| 1996 5.2L Grand Cherokee | ||
|---|---|---|
| Terminal | Wire | Description |
| 1 | White with black stripe (WHT/BLK) | 5 Volts |
| 2 | Red with white stripe (RED/WHT) | MAP Signal |
| 3 | Black with light blue striped (BLK/LT BLU) | Ground |
As you're probably already aware, the MAP sensor's job is to measure the amount of vacuum inside the intake manifold.
With the key on and engine off (no vacuum present in its vacuum hose), the MAP sensor produces a voltage signal that's around 4.5 to 4.7 Volts DC.
As vacuum is applied to the MAP sensor, it's voltage signal starts to decrease.
If the MAP sensor is bad, you'll notice that it's voltage signal does not decrease no matter the amount of vacuum that is applied to it.
TEST 1: Testing The MAP Sensor Voltage Signal
As mentioned at the beginning of the tutorial, we're going to apply vacuum to the MAP sensor to find out if it's producing a voltage signal that decreases.
The wire that we're gonna' connect the multimeter to, is the wire labeled with the number 2 in the photo above.
This wire is the red with white stripe (RED/WHT) wire of the MAP sensor's connector.
You can apply vacuum to the MAP sensor using a vacuum pump or you can use your mouth.
NOTE: If you don't have a vacuum pump you and would like to purchase one, check out this link: HTOMT 2 In 1 Vacuum Pump Test Set.
IMPORTANT: The manifold absolute pressure (MAP) sensor must remain connected to its electrical connector for this test to function properly. To be able to access the voltage inside the signal wire, you'll need to use either a back probe or a wire piercing probe. You can see an example of this tool here: Wire Piercing Probe.
Let's get started:
- 1
Remove the MAP sensor from the throttle body.
- 2
Connect your vacuum pump to the MAP sensor's vacuum inlet port.
NOTE: Reconnect the MAP sensor to its connector if you disconnected it. - 3
Place your multimeter in Volts DC mode.
- 4
Connect the red multimeter test lead to the RED/WHT wire of the MAP sensor's connector.
This wire is identified by the number 2 in the photo above.
Remember, the MAP sensor must remain connected to its 3 wire connector. - 5
Ground the black multimeter test lead directly on the battery negative (-) terminal.
- 6
Turn the key on but don't start the engine. This will power up the MAP sensor and you should see a reading of around 4 to 4.7 Volts DC on your multimeter.
- 7
Now, apply vacuum to the MAP sensor with the vacuum pump (or your mouth). The voltage signal value should decrease.
If you're using a vacuum pump you'll see the following approximate values: At 5 in.Hg → 3.9 Volts. At 10 in.Hg → 3 Volts. At 15 in.Hg → 2.1 Volts. At 20 in.Hg → 1.2 Volts. - 8
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 examine your test:
CASE 1: The MAP voltage signal decreased and increased as you applied and released vacuum. This is the correct test result.
This test result confirms that the MAP sensor is working correctly (not defective). It also lets you know that the MAP sensor is getting 5 Volts and Ground.
CASE 2: The MAP voltage signal DID NOT decrease/increase as you applied and released vacuum. This test result usually indicates that the MAP sensor is defective.
To find out, the next step is to see if the orange (ORG) wire is feeding the MAP sensor with 5 Volts DC. For this test go to: TEST 2: Making Sure The MAP Sensor Has 5 Volts.
CASE 3: The multimeter DID NOT register any voltage. This test result usually indicates that the MAP sensor is defective.
To find out, the next step is to see if the orange (ORG) wire is feeding the MAP sensor with 5 Volts DC. For this test go to: TEST 2: Making Sure The MAP Sensor Has 5 Volts.
