TEST 1: Checking For Power (12 V)

Making Sure The Ignition Module Is Getting Power. GM 3.8L Ignition Control Module and Crank (3X, 18X) Sensor Test

We'll begin by checking that the ignition control module is receiving 12 Volts. Space to test these circuits comfortably is almost nonexistent so, I recommend using a wire piercing probe to accomplish all of the tests in this article.

To see what a wire piercing probe looks like, go to: Wire Piercing Probe Review (Power Probe PWPPPPP01). Whatever method you use, the key here is to be careful. Remember to use common sense and take all safety precautions to solve the problem, not add to it.

Although the test below is done with a multimeter, you can also use a test light if you like.

  1. 1

    Put the multimeter in VOLTS DC mode.

    Don't have a digital multimeter? Need to buy one? Click here to see my recommendations: Buying A Digital Multimeter For Automotive Diagnostic Testing.

  2. 2

    Disconnect the ignition control module (ICM) from its connector.

    With the red multimeter test lead and a wire piercing probe, probe the PINK wire of the connector shown in the figure above. This is the wire labeled with the letter P in the illustration above.

  3. 3

    With the black multimeter test lead probe the battery negative (-) terminal.

  4. 4

    Turn key ON with the engine OFF. You should see 10 to 12 Volts on the multimeter.

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

CASE 1: Your multimeter registered 10 to 12 Volts. This tells you that the module is getting power.

The next step is to make sure the ICM is getting Ground. Go to: TEST 2: Testing The Ground Circuit.

CASE 2: Your multimeter DID NOT register 10 to 12 Volts. This test result lets you know that the ignition control module is not getting power.

You must find out why you're missing this voltage. Without this voltage the ignition control module (ICM) will not function. Re-check all of your connections and re-test. If voltage is still not present, you have just eliminated the ICM as being bad. After repairing the cause of the missing voltage, the vehicle should start.

TEST 2: Testing The Ground Circuit

Making Sure The Ignition Module Is Getting Ground. GM 3.8L Ignition Control Module And Crank (3X, 18X) Sensor Test

Here we'll check that the ignition control module (ICM) is receiving a good GROUND. The wire (circuit) that provides this Ground is the K circuit.

There's a good chance that your specific vehicle does not have this circuit (wire) in the connector. This is normal, since the module will get ground thru' its case. You can skip this step and go to the next one.

NOTE: If your vehicle's ignition module does not have this Ground wire, take a look at B. Jones' feedback about his no start problem due to the ignition module not getting a good Ground due to aluminum oxide (rust) on the module's case here: Real Life Case Study #1 (Thank you Bill for you feedback!).

These are the test steps:

  1. 1

    Put the multimeter in VOLTS DC mode. Disconnect the ignition module from its connector.

  2. 2

    Probe the wire labeled with the letter K with the black multimeter test lead and a wire piercing probe.

    This wire is the BLACK with WHITE stripe wire of the ICM connector.

  3. 3

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

  4. 4

    You should see 10 to 12 Volts on the multimeter.

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

CASE 1: Your multimeter registered 12 Volts. This tells you that the module does have a good path to Ground.

The next step is to make sure that the ignition module is feeding the crankshaft position sensor with power. For this test go to: TEST 3: Making Sure The Crank Sensor Is Getting Power.

CASE 2: Your multimeter DID NOT register 12 Volts. This means that the ICM is not getting Ground. This usually because the wire has an open somewhere between the connector and ground.

Since the ignition module (ICM) needs this GROUND to function your next step is to restore this Ground.

Buick Vehicles:

  • Century
    • 1993
  • LeSabre
    • 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
  • Park Avenue (& Ultra)
    • 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005

Buick Vehicles:

  • Regal
    • 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
  • Riviera
    • 1993, 1994, 1995, 1996, 1997, 1998, 1999
  • Skylark
    • 1993

Chevrolet Vehicles:

  • Camaro
    • 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002
  • Impala
    • 2000, 2001, 2002, 2003, 2004, 2005
  • Lumina (& MPV)
    • 1993, 1994, 1995, 1998, 1999
  • Monte Carlo
    • 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005

Oldsmobile Vehicles:

  • 88 (& 88 Royale)
    • 1993, 1994, 1995, 1996, 1997, 1998
  • 98 Regency
    • 1993, 1994, 1995, 1996
  • Achieva
    • 1993
  • Cutlass Ciera (& Cruiser)
    • 1993

Oldsmobile Vehicles:

  • Intrigue
    • 1998, 1999
  • LSS
    • 1996, 1997, 1998, 1999
  • Regency
    • 1997, 1998
  • Silhouette
    • 1993, 1994, 1995

Pontiac Vehicles:

  • Bonneville
    • 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
  • Firebird
    • 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002
  • Grand Am
    • 1993

Pontiac Vehicles:

  • Grand Prix
    • 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
  • Trans Sport
    • 1993, 1994, 1995