Chrysler 4-Wire MAP Sensor Diagnostic Test

TEST 2: Verifying The 5 Volt Reference Signal

The manifold absolute pressure (MAP) sensor on your Chrysler 2.0L, 3.2L, and 3.5L vehicle needs power to work. This power comes in the form of 5 Volts DC from the fuel injection computer.

This test will help you to confirm if these 5 Volts are present or not. This is what you'll need to do:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Disconnect the MAP sensor from its connector.

3. 3

   Connect the red multimeter test lead to the wire labeled with the number 2.
   
   NOTE: It's important that you avoid probing the front of the connector or you run the risk of damaging the female terminal.

4. 4

   Connect the black multimeter test lead to a good and clean Ground point on the engine or directly on the negative battery terminal.

5. 5

   Have your helper rotate the key to its ON position but don't start the engine.

6. 6

   The multimeter should display 4.5 to 5 Volts on its screen.

Let's take a look at what your test results mean:

CASE 1: The multimeter registered 4.5 to 5 Volts. This is the correct test result. It confirms that the fuel injection computer and the circuit (wire) is supplying the MAP sensor with power.

The next step is to test the Ground circuit of the manifold absolute pressure (MAP) sensor, go to: TEST 3: Verifying Ground To The MAP Sensor.

CASE 2: The multimeter DID NOT register 4.5 to 5 Volts. Then the computer or the circuit are NOT providing the voltage that the TPS needs to operate.

The two most likely reasons for this are: 1) an open-circuit problem in the circuit or 2) the PCM may be fried.

Altho' it's beyond the scope of this tutorial to test these two conditions, you have now eliminated the manifold absolute pressure (MAP) sensor on your Chrysler 2.0L, 3.2L, or 3.5L vehicle as being the cause of the problem and/or the MAP sensor diagnostic trouble code (DTC) lighting up the check engine light (CEL).

TEST 3: Verifying Ground To The MAP Sensor

So far you have verified that the MAP sensor is not creating a MAP signal (TEST 1) and that the MAP sensor is getting power (TEST 2).

The second step, before condemning the manifold absolute pressure (MAP) sensor, is to verify that it also has a good Ground.

NOTE: The PCM is the one that provides this Ground internally. So be careful and don't accidentally or intentionally apply power (12 Volts) to this circuit or you'll fry the PCM.

OK, here are the test steps:

1. 1

   Set your multimeter to Volts DC mode.

2. 2

   Disconnect the MAP sensor.

3. 3

   Probe the wire labeled with the number 4 with the black multimeter test lead.
   
   NOTE: Avoid probing the front of the connector or you run the risk of damaging the female terminal.

4. 4

   With the red multimeter test lead, probe the battery positive (-) terminal.

5. 5

   Have your helper turn the key to its ON position but don't start the engine.

6. 6

   Your multimeter will display 10 to 12 Volts if this circuit is OK and the PCM is providing a good path to Ground.

Let's take a look at what your test results mean:

CASE 1: The multimeter showed 10 to 12 Volts. This is the correct test result and let's you conclude that the PCM and the wire/circuit (that supply this Ground) are OK.

This multimeter test result also confirms that the MAP sensor is bad and needs to be replaced only if you have:

• Verified that the MAP sensor is not producing a decreasing voltage signal as you apply vacuum to it (TEST 1).
• Verified that the MAP sensor is getting 5 Volts (TEST 2).
• Verified, in this test section, that the MAP sensor is getting Ground.

If you need to replace the MAP sensor, check out my recommendations: Where To Buy The MAP Sensor And Save.

CASE 2: The multimeter DID NOT show 10 to 12 Volts. Then this indicates a problem with either the PCM (internal fault/problem) or an open in the wire between the MAP sensor and the PCM itself.

Altho' testing these two conditions are beyond the scope of this tutorial, you have now eliminated the MAP sensor on your Chrysler 2.0L, 3.2L, or 3.5L vehicle as being the cause of the problem and/or the MAP sensor diagnostic trouble code (DTC) lighting up the check engine light (CEL).

MAP Code Won't Go Away

So you've tested the MAP sensor and according to the test results, it's good, but the check engine light keeps coming back on even after you erased the diagnostic trouble code (DTC) from the computer's (PCM) memory. Well, here are a couple of suggestions that might inspire your next diagnostic move:

1. The MAP sensor's O-rings, the ones located on the vacuum inlet nipple are missing or are too old and they're not sealing properly. Visually check the O-rings and replace if necessary.
2. The engine has several cylinders with very low engine compression causing it to idle rough and thus producing low or erratic vacuum. For this I suggest a compression test.
3. The MAP sensor is failing intermittently. Which means that it works fine most of the time, but every now and then it doesn't:
   • I have found that the best way to test these intermittent problems is to slightly tap the MAP sensor with the handle of a screw-driver and see if this tapping screws up the voltage readings as I apply vacuum.
4. The MAP sensor's connector is bad, usually the locking tab is broken and the connector has worked itself loose, causing an intermittent false connection.
5. Your fuel pump is starting to go bad and is not sending enough fuel and/or fuel pressure up to the fuel injectors. I suggest a fuel pump test.