How To Test The MAP Sensor (1993-1996 2.2L Buick Century, Oldsmobile Cutlass Ciera)

TEST 2: Making Sure The MAP Sensor Is Getting 5 Volts

The MAP sensor gets power from the fuel injection computer in the form of 5 Volts DC.

These 5 Volts are delivered to the MAP sensor by the grey (GRY) wire of the MAP sensor's 3-wire connector.

In the photo above, the GRY wire is labeled with the letter C.

Let's get started:

1. 1

   Place your multimeter still in Volts DC mode.

2. 2

   Disconnect the MAP sensor from its electrical connector.

3. 3

   Probe the wire labeled with the letter C, in the photo above, with the red multimeter test lead.
   
   The wire labeled with the letter C, in the photo above, is the GRY of the connector.
   
   NOTE: You can probe the front of the wire's female terminal. If you do, be careful not to damage it with your multimeter's probe.

4. 4

   Now Ground the black multimeter test lead on the battery's negative (-) post.

5. 5

   Turn the key ON but don't start the engine.

6. 6

   Your multimeter should show you a voltage value around 4.5 to 5 Volts DC.

OK, let's take a look at what your results mean:

CASE 1: The multimeter registered 5 Volts. This is the correct and expected test result.

Since the MAP sensor is receiving power, your next step is to make sure that it's getting Ground. Go to: TEST 3: Making Sure The MAP Sensor Is Getting Ground.

CASE 2: The multimeter DID NOT register 5 Volts. Without power, the MAP sensor will not function.

Although it's beyond the scope of this tutorial, your next step is to find out why these 5 Volts are missing and restore them. Once you restore power to the MAP sensor, it'll start functioning again.

TEST 3: Making Sure The MAP Sensor Is Getting Ground

So far, your previous two tests have confirmed:

• The MAP sensor voltage signal does not decrease/increase as you apply/release vacuum to the sensor (TEST 1).
• The MAP sensor is receiving 5 Volts (TEST 2).

In this last test section, you'll check that the black (BLK) wire is delivering Ground to the MAP sensor.

In the photo above, I've labeled the BLK wire with the letter A.

These are the test steps:

1. 1

   Place your multimeter still in Volts DC mode.

2. 2

   Disconnect the MAP sensor from its electrical connector.

3. 3

   Probe the wire labeled with the letter A in the image above, with the black multimeter test lead.
   
   The wire labeled with the letter A is the BLK wire of the connector.
   
   NOTE: You can probe the front of the wire's female terminal. If you do, be careful not to damage it with your multimeter's probe.

4. 4

   Connect the red multimeter test lead on the battery's positive (+) post.

5. 5

   Turn the key ON but don't start the engine.

6. 6

   Your multimeter register 10 to 12 Volts DC.

OK, let's interpret your test result:

CASE 1: The multimeter registered 10 to 12 Volts. This is the correct test result and tells you that the MAP sensor is receiving Ground.

You can correctly conclude that the manifold absolute pressure sensor is bad and needs replacement if you have:

• Confirmed the MAP sensor voltage signal does not decrease/increase as you apply/release vacuum to the sensor (TEST 1).
• Confirmed the MAP sensor is receiving 5 Volts (TEST 2).
• Confirmed the MAP sensor is receiving Ground (this test section).

CASE 2: The multimeter DID NOT register 10 to 12 Volts. Without Ground, the MAP sensor will not function.

Although it's beyond the scope of this tutorial, your next step is to find out why the MAP sensor is not receiving Ground and resolve the problem. Once you restore Ground to the MAP sensor, it'll start functioning again.

MAP Sensor Code Won't Go Away

In some cases, a MAP sensor trouble code keeps returning and illuminating the check engine light even though the MAP sensor is good.

If this is happening in your case, then one or more of the following problems could be behind the issue:

1. The o-ring (rubber gasket) on the vacuum inlet of the MAP sensor is missing or cracked.
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 an engine compression test.
   • How To Do An Engine Compression Test (GM 2.0L, 2.2L, 2.5L).
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.
   • How To Test The Fuel Pump (1993-1996 2.2L Buick Century, Oldsmobile Cutlass Ciera).

More 2.2L Buick Century And Oldsmobile Cutlass Ciera Test Tutorials

If this tutorial was helpful, be sure and take a look at all of the 2.2L Buick Century and Oldsmobile Cutlass Ciera diagnostic tutorials in this index:

• GM 2.2L Index Of Articles.

Here's a sample of the tutorials you'll find there:

• How To Test The Fuel Pump (1993-1996 2.2L Buick Century, Oldsmobile Cutlass Ciera).
• How To Test The TPS (1993-1996 2.2L Buick Century, Oldsmobile Cutlass Ciera).
• How To Test The EGR Valve (1993-1995 2.2L Buick Century, Oldsmobile Cutlass Ciera).
• How To Test Engine Compression (1993-1996 2.2L Buick Century, Oldsmobile Cutlass Ciera).