If the check engine light, on your 3.8L V6 mini-van is illuminated by a P0108 or a P0109 diagnostic trouble code, this is the tutorial that'll help you test the MAP sensor.
In this tutorial, I'll explain the three tests you need to do to find out if the MAP sensor is bad or not. All three are done with a multimeter.
This is a very accurate test that will let you know beyond a shadow of a doubt if the MAP sensor is bad or not.
Contents of this tutorial:
You can find this tutorial in Spanish here: Como Probar El Sensor MAP (2001-2004 3.8L V6 Chrysler, Dodge Mini-Van) (at: autotecnico-online.com).
APPLIES TO: This tutorial, on how to test the MAP sensor, applies to the following vehicles:
- 3.8L V6 Chrysler Town & Country: 2001, 2002, 2003, 2004.
- 3.8L V6 Dodge Grand Caravan: 2001, 2002, 2003.
NOTE: If you need the MAP sensor test for the 1996-2000 3.8L Chrysler, Dodge, and Plymouth mini-vans, consult this tutorial: How To Test The MAP Sensor (1996-2000 3.8L V6 Chrysler, Dodge, Plymouth Mini-Van).
Symptoms Of A Bad MAP Sensor
The fuel injection computer, of your minivan, needs to know three things to be able to know how much air is entering the engine and to be able to inject the correct amount of fuel.
These three things are intake air temperature, engine RPM, and engine load.
And as you've guessed it, the sensor that provides the engine load information is the manifold absolute pressure sensor.
Since the MAP sensor is such a critical component of the engine management system, when it fails you're going to see the check engine light illuminated by one of the following trouble codes:
- P0107: MAP Sensor Voltage Too Low.
- P0108: MAP Sensor Voltage Too High.
You're also gonna' see one or more of the following symptoms:
- Bad gas mileage.
- Black smoke coming out of the tail pipe, especially when you accelerate the vehicle.
- No power and/or hesitation as you accelerate the vehicle. It feels like all of a sudden someone cut the power out momentarily as you step on the gas to get the vehicle moving.
How The MAP Sensor Works
The manifold absolute pressure (MAP) sensor's job is to measure the amount of vacuum that is created by the downward stroke of the engine pistons and is one of the most important inputs the PCM needs to make you car or mini-van run optimally.
So here, in a nutshell, is how the MAP sensor works when you crank and start your 3.8L V6 Chrysler (Dodge, Plymouth) mini-van:
- The fuel injection computer supplies 5 Volts and Ground to the MAP sensor.
- At idle the MAP sends the PCM computer a DC voltage signal of about 1.1 to 1.8 Volts.
- When you step on the accelerator pedal to accelerate the engine, vacuum immediately increases which causes the MAP signal voltage to the computer to decrease.
- With this decreasing voltage signal, the computer knows it's time to inject more fuel, advance ignition timing, and a host of other things it has to do to keep your Chrysler (Dodge, Plymouth) mini-van running optimally.
- As you let go off the accelerator pedal to slow down, the throttle plate closes and of course the MAP sensor sends the info to the computer as it returns to its idle voltage signal, till the whole cycle begins again.
Pretty easy stuff? The cool thing is that testing the MAP sensor's performance is as easy too.
Where To Buy The MAP Sensor And Save
The following links will help you to comparison shop for the MAP sensor and save a few bucks!:
If you're not sure if the above MAP sensor fit your particular 3.8L V6 Chrysler (Dodge, Plymouth) mini-van 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: Checking The MAP Signal With A Multimeter
The very first thing that we're going to do is verify the MAP voltage signal that the sensor is producing.
To be a bit more specific, we're going to remove the MAP sensor from its place on the intake manifold and then connect it to a vacuum pump.
We're going to leave the MAP sensor connected to its electrical connector so that the fuel injection computer can power it up.
Then we'll apply vacuum to it and see if the MAP voltage signal decreases.
If the MAP voltage signal does not decrease, as vacuum is being applied to the sensor, then we can conclude that the MAP sensor is either defective or it's not getting power or Ground.
If you don't have a vacuum pump, no worries. You can use your mouth to apply a vacuum to the MAP sensor.
NOTE: You'll need a multimeter to test your vehicle's MAP sensor. If you don't have one and need to buy one or upgrade yours, the following recommendation will help: Buying A Digital Multimeter For Automotive Diagnostic Testing.
IMPORTANT: The MAP sensor must remain connected to its electrical connector to read its voltage signal. You'll need to use a back-probe on the connector or a wire-piercing probe on the wire to access the MAP signal. You can see an example of this tool here: Wire Piercing Probe Review.
OK, let's start:
- 1
Remove the MAP sensor from the intake manifold. If you needed to disconnect the MAP sensor from it's electrical connector to remove it, reconnect it now (the MAP sensor must remain connected to its connector for this test).
- 2
Select Volts DC Mode on your multimeter.
- 3
Connect the red multimeter test lead to the violet with brown stipe (VIO/BRN) wire of the MAP sensor's connector.
In the photo above I've identified the VIO/BRN wire with the number 1.
NOTE: The MAP sensor must remain connected to its electrical connector to test the MAP signal voltage. - 4
Ground the black multimeter test lead on the battery negative (-) terminal.
- 5
Have your helper turn the key On but don't start the engine.
- 6
You should see a voltage around 4.5 Volts DC registering on your multimeter. If it doesn't, don't worry about it just yet, continue with the other steps.
- 7
Connect your vacuum pump to the MAP sensor using a large diameter hose (I use a 3/8 fuel hose).
Whatever hose you use, it's important that it makes a tight seal on both the MAP sensor's vacuum inlet nipple and the vacuum hose. - 8
Apply vacuum to the MAP sensor till the gauge's needle reaches 5 in. Hg of vacuum. These are the readings you should have as you pump the vacuum pump to different vacuum levels:
1.) 0 in. Hg ...... 4.7 Volts.
2.) 5 in. Hg ...... 3.9 Volts.
3.) 10 in. Hg .... 3.0 Volts.
4.) 15 in. Hg .... 1.1 Volts. - 9
Release the vacuum you've applied. The voltage reading should go back up to the value you registered in step 6.
Let's take a look at what your test results mean:
CASE 1: As you applied/released vacuum, the voltage decreased/increased. This is the correct test result.
You can conclude that the manifold absolute pressure (MAP) sensor is working find and is not defective. No further MAP sensor tests are needed.
Now, if the MAP sensor trouble code won't go away, take a look at the info found at: MAP Code Will Not Go Away for a few more suggestions as to what could be causing the MAP sensor diagnostic trouble code (DTC).
CASE 2: As you applied/released vacuum, the voltage DID NOT decrease/increase. This test result usually confirms that the MAP sensor is fried and that it needs to be replaced. But before you replace it, make sure it's getting 5 Volts and Ground.
The next test is to make sure that the MAP sensor is getting 5 Volts. Go to: TEST 2: Making Sure The MAP Sensor Is Getting 5 Volts.
CASE 3: The multimeter DID NOT register any voltage. This isn't good, but doesn't condemn the manifold absolute pressure (MAP) sensor as bad yet.
The next test is to make sure that the MAP sensor is getting 5 Volts. Go to: TEST 2: Making Sure The MAP Sensor Is Getting 5 Volts.
