How To Test The MAP Sensor (1992-1995 1.5L Honda Civic)

TEST 2: Verifying MAP Sensor Has 5 Volts And Ground

If in TEST 1 the MAP sensor's voltage signal value did not move down or up, then the next step is to make sure it's getting power and Ground. Why?

Because if it's missing power (or ground), it won't produce the decreasing/increasing voltage signal your were looking for (and you might up end replacing a part your Civic doesn't need).

These are the 2 wires that you'll be testing:

• On 1.5L Civic DX and LX models:
  • The YEL/RED wire supplies 5 Volts.
  • The GRN/WHT wire supplies Ground.
• On 1.5L Civic CX models:
  • The YEL/GRN wire supplies 5 Volts.
  • The GRN/BLU wire supplies Ground.

IMPORTANT: Your Honda Civic's fuel injection computer is the one that feeds both power and Ground to the manifold absolute pressure (MAP) sensor. Be careful and don't short the Ground wire (circuit) to battery voltage or you'll fry it.

OK, with your multimeter set to Volts DC this is what you need to do:

1. 1

   Verify that the YEL/RED (or YEL/GRN) wire has voltage ( 4.5 to 5 Volts DC ) with the key ON but engine OFF.
   
   1.) Connect the red multimeter test lead (using the appropriate tool) to the YEL/RED (or YEL/GRN) wire.
   
   2.) Connect the black multimeter test lead to the negative battery terminal.
   
   3.) Your multimeter should read 4.5 to 5 Volts DC.

2. 2

   Verify that the GRN/WHT (or GRN/BLU) wire has Ground with the key on but engine off.
   
   1.) Connect the black multimeter test lead (using the appropriate tool) to the GRN/WHT (or GRN/BLU) wire.
   
   2.) Connect the red multimeter test lead to the battery positive (+) terminal.
   
   3.) Your multimeter should read 10 to 12 Volts DC.

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

CASE 1: The multimeter confirms that the MAP sensor is being fed power and Ground. Great, this test results tells us that the MAP sensor is getting both and thus you can rule out electrical wiring issues as behind the cause of the MAP sensor trouble.

Now, you can confidently conclude that the MAP sensor is bad only if:

• You have confirmed that the MAP sensor voltage signal IS NOT increasing/decreasing while applying/releasing vacuum (in TEST 1).
• You have confirmed that the MAP sensor is getting power (5 Volts) and Ground.

CASE 2: The multimeter confirms that the MAP sensor IS NOT being fed power or Ground. Double check that you're testing the correct MAP sensor harness terminal wire and repeat the test.

If your multimeter still doesn't show the indicated voltages, then we can conclude that there's an open in the wire between the MAP sensor harness connector and the PCM's harness connector. In the extreme of cases, the PCM has an internal problem (although this is very rare).

Although testing these two conditions are beyond the scope of this article, you have now eliminated the manifold absolute pressure (MAP) on your 1.5 Honda Civic as being the cause of the problem and/or the MAP sensor diagnostic trouble code (DTC) lighting up the check engine light (CEL).

More 1.5L Honda Civic Tutorials

You can find a complete list of 1.5L Honda Civic tutorials in this index:

• Honda 1.5L Index of Articles.

Here's a small sample of the tutorials you'll find in the index:

• How To Test The PGM-FI Main Relay (1992-1995 1.5L Honda Civic).
• How To Test The Throttle Position Sensor (1992-1995 1.5L Honda Civic).
• How To Test Engine Compression (Honda 1.5L).
• How To Test The Fuel Pump In 2 Tests (1992-1995 1.5L Honda Civic And Honda Civic Del Sol).
• How To Test The Igniter, Ignition Coil Accord, Civic, CRV, And Odyssey (at easyautodiagnostics.com).