How To Test The MAP Sensor (1992-1996 5.2L, 5.9L V8 Dodge Ram Pickup)

By: Abraham Torres-Arredondo
Created: 04 April 2014
Updated: 15 April 2025
Articl Id: 578

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TEST 2: Making Sure The MAP Sensor Is Getting Power

Making Sure The MAP Sensor Is Getting Power. How To Test The MAP Sensor (1992, 1993, 1994, 1995, 1996 5.2L, 5.9L V8 Dodge Ram Pickup)

Now that you have confirmed that the MAP sensor IS NOT producing a varying MAP voltage signal on the DK GRN/RED wire, we now need to make sure that the VIO/WHT wire (of the MAP sensor connector) is feeding the sensor with power.

This power comes directly from the PCM and is in the form of 5 Volts DC.

The wire that feeds these 5 Volts to the MAP sensor is the violet with white stripe (VIO/WHT) wire of the connector.

NOTE: It's not a good idea to probe the front of the MAP sensor harness connector to test for this voltage since you could permanently damage the female metal terminal. Instead, you should back-probe the connector with the appropriate tool or use a wire-piercing probe.

OK, let's get started:

1
Place your multimeter in Volts DC mode.
2
Disconnect the MAP sensor from its electrical connector.
3
Connect the red multimeter test lead to the VIO/WHT wire of the MAP sensor harness connector.

This is the wire that connects to the terminal labeled with the number 3 in the illustrations in the image viewer.
4
Ground the black multimeter test lead directly on the battery negative (-) terminal.
5
Have a helper turn the key to the On position, but don't crank or start the engine after the multimeter test leads have been set up.
6
Your multimeter should register 4.5 to 5 Volts DC if the VIO/WHT wire is feeding the manifold absolute pressure (MAP) sensor with power.

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

CASE 1: The VIO/WHT wire has power (4.5 to 5 Volts). This is the correct and expected test result and lets you know that your Dodge Ram pickup's manifold absolute pressure (MAP) sensor is getting power.

Your next step is to make sure that the MAP sensor is getting Ground on the BLK/LT BLU (black w/ light blue) wire. For this test, go to: TEST 3: Making Sure The MAP Sensor Is Getting Ground.

CASE 2: The VIO/WHT wire DOES NOT have power (4.5 to 5 Volts). Check that the key is in the on position and that you're testing the correct wire and re-test.

If your multimeter still shows that the VIO/WHT wire DOES NOT have power, then you've found the reason why the MAP sensor did not create a voltage signal in TEST 1.

Although it's beyond the scope of this tutorial to find the reason why these 5 Volts are missing, you'll need to get yourself a wiring diagram (for your particular Dodge Ram pickup) and check the continuity of this wire between the MAP sensor and the PCM.

TEST 3: Making Sure The MAP Sensor Is Getting Ground

Making Sure The MAP Sensor Is Getting Ground. How To Test The MAP Sensor (1992, 1993, 1994, 1995, 1996 5.2L, 5.9L V8 Dodge Ram Pickup)

You've reached this point because you have confirmed that:

One: The check engine light is being lit by a MAP sensor trouble code.

Two: The MAP sensor IS NOT creating an increasing/decreasing throttle plate voltage signal on the DK GRN/RED wire (TEST 1).

Two: The VIO/WHT wire, of the MAP sensor connector, does register 5 Volts DC (TEST 2).

The last test is to make sure that the BLK/LT BLU wire is feeding the MAP sensor with Ground.

NOTE: Be careful and do not short this wire to battery voltage, or you'll fry your Dodge pickup's PCM.

These are the test steps:

1
Place your multimeter in Volts DC mode.
2
Disconnect the MAP sensor from its electrical connector.
3
Connect the black multimeter test lead to the BLK/LT BLU wire of the MAP sensor harness connector.

This is the wire that connects to the terminal labeled with the number 1.
4
Connect the red multimeter test lead directly on the battery's positive (+) terminal.
5
Have a helper turn the key to the On position, but don't crank or start the engine after the multimeter test leads have been set up.
6
Your multimeter should register 12 Volts DC if the BLK/LT BLU wire is feeding the MAP sensor with Ground.

Let's interpret your test results:

CASE 1: The multimeter registered 12 Volts DC. This confirms that the MAP sensor is getting Ground from the PCM. Now, since you have:

Confirmed that the MAP sensor is not creating an increasing/decreasing voltage signal (TEST 1).
Confirmed that the VIO/WHT wire is providing power (TEST 2).

And in this test step you have confirmed that the MAP sensor is getting Ground on the BLK/LT BLU wire then you can conclude that the MAP sensor is defective and needs to be replaced.

If you'd like to save a few bucks on the MAP sensor, check out the section: Where To Buy The MAP Sensor And Save.

CASE 2: The multimeter DID NOT register 12 Volts DC. Re-check all of your test connections and repeat the test.

If the multimeter still does not show the indicated voltage, then you've found the reason why the MAP sensor did not create a voltage signal in TEST 1.

Although it's beyond the scope of this tutorial to find the reason why this Ground is missing, you'll need to get yourself a wiring diagram (for your particular Dodge Ram pickup) and check the continuity of this wire between the MAP sensor and the PCM.

MAP Sensor Code Won't Go Away

So, you've run the tests on the MAP sensor and everything checks out fine —or maybe you even replaced it with a new one, but the same problems persist. In other words, the issue remains unresolved. To make things worse, the check engine light keeps reappearing even after you've cleared the diagnostic trouble code (DTC) from the computer's memory.

If you're unsure what to try next, here are a few ideas that might help guide your next steps in troubleshooting the issue:

Significant vacuum leak: A large vacuum leak can throw off the air/fuel mixture, making it run lean. This often results in a rough idle and can mislead the FI computer into incorrectly flagging the MAP sensor as the problem.
Cracked or worn vacuum elbow: The rubber elbow that connects the MAP sensor to the vacuum port on the throttle body may be cracked, brittle, or completely torn due to age-related dry rot.
Poor engine compression: Low compression across multiple cylinders can cause an unstable idle and create weak or inconsistent vacuum signals. This might lead to incorrect MAP sensor readings. In this case, a compression test is highly recommended:
- How To Test Engine Compression (1989-2003 5.2L, 5.9L V8 Dodge Ram Pickup).
MAP sensor acting up intermittently: Sometimes the sensor isn't completely faulty —it works most of the time but occasionally malfunctions.
- In my experience, the most effective way to catch this kind of issue is to gently tap the sensor with a screwdriver handle while applying vacuum and monitoring voltage readings. If the readings fluctuate with the tapping, the sensor is likely faulty.
Loose or broken connector: A faulty connector —especially one with a broken locking tab— may not stay firmly attached, leading to an inconsistent electrical connection that mimics sensor failure.
Weak fuel pump: If the fuel pump is starting to fail, it may not be delivering sufficient fuel or pressure to the injectors. You'll want to check fuel pressure using a gauge to confirm it's within the proper range.

More 5.2L, 5.9L Dodge Ram Diagnostic Tutorials

I've written quite a few 5.2L, 5.9L V8 Dodge ‘how to test’ tutorials that may help you troubleshoot the issues on your Dodge Ramp pickup. You can find them in these two indexes:

Here's a small sample of the articles/tutorials you'll find in these indexes: