TEST 3: Checking The Power And Ground Circuits

How To Test The 1.8L VW Ignition Control Module (Ignitor) -easyautodiagnostics.com

If you've reached this point, you have:

  1. You identified the ‘dead’ cylinder.
  2. You then proceeded to remove the ignition coil that belonged to the ‘dead’ cylinder and replaced it with one of the other 3 ignition coils.
  3. Next, you spark tested this ignition coil with a spark tester and IT DID NOT SPARK.

Well, there's a good chance that the ignition control module is bad and in this test step, I'm gonna' help you confirm that.

What you'll need to do is 1) Make sure that the ignition coil is getting power (12 Volts) on the wire labeled with the number 3 (in the photo below). 2) That the coil is getting Ground on the wire labeled with the number 2 and then finally test the continuity of the Switching Signal wire labeled with the number 1.

OK, to get this show on the road, in test step, you'll make sure that the ignition coil is getting both power and Ground:

STEP 1:

  1. Unplug the ignition coil that did not spark (and that belongs to the ‘dead’ cylinder) from it's 3 wire electrical connector.
  2. Place your multimeter in Volts DC mode and:
    1. Check that there's 10 to 12 Volts with the Key On Engine Off on the wire labeled with the number 3.

STEP 2:

  1. Now, you're gonna' test the Ground circuit:
    1. Set the multimeter to Volts DC mode.
    2. Connect the red multimeter test lead to the battery positive terminal.
    3. Connect the black multimeter test lead to the wire labeled with the number 2.
    4. Your multimeter should register 10 to 12 Volts DC.
  2. Let's interpret your test results below.

CASE 1: The multimeter registered Power and Ground in the indicated wires. This is good and the correct test result. The next step is to check the Continuity of the Switching Signal wire. Go to: TEST 4: Testing The Continuity Of The Signal Circuit.

CASE 2: The multimeter DID NOT register one of the following: Power or Ground in the indicated wires. Repeat the tests and confirm you test result.

If you still are missing either Power or Ground in the indicated wires above, then this test result tells you that the ignition coil and the ignition module are not the cause of the misfire.

Restoring either the missing Power or Ground in the circuit will get the ignition coil to spark again and resolve the misfire condition.

TEST 4: Testing The Continuity Of The Signal Circuit

How To Test The 1.8L VW Ignition Control Module (Ignitor) -easyautodiagnostics.com

Alright, this is the last test you need to perform to confidently accuse the ignition coil as being bad.

What you'll need to do is make sure that there's continuity in the circuit that feeds the Switching signal to the ignition coil between the ignition control module 4-wire connector and the circuit labeled with the number 1 of the ignition coil 3-wire connector.

OK, to get this last test started, you'll need to choose one of the following cases that applies to the specific ignition coil that is not sparking:

No spark from ignition coil for cylinder #1

  1. Disconnect the 4-wire ignition control module connector.
  2. Disconnect the cylinder #1 ignition coil from its 3-wire electrical connector.
  3. Place your multimeter in Ohms mode and measure the continuity of the signal circuit by:
    1. Probing the wire labeled with the number 1 of the ignition coil's connector (see photo below).
    2. Probing the wire that corresponds to the number 1
      1. -NOTE: This number is embossed on the ignition control module.
  4. The multimeter should register 1 Ohm or less if the wire (circuit) is OK.

No spark from ignition coil for cylinder #2

  1. Disconnect the 4-wire ignition control module connector.
  2. Disconnect the cylinder #2 ignition coil from its 3-wire electrical connector.
  3. Place your multimeter in Ohms mode and measure the continuity of the signal circuit by:
    1. Probing the wire labeled with the number 2 of the ignition coil's connector (see photo below).
    2. Probing the wire that corresponds to the number 1
      1. -NOTE: This number is embossed on the ignition control module.
  4. The multimeter should register 1 Ohm or less if the wire (circuit) is OK.

No spark from ignition coil for cylinder #3

  1. Disconnect the 4-wire ignition control module connector.
  2. Disconnect the cylinder #3 ignition coil from its 3-wire electrical connector.
  3. Place your multimeter in Ohms mode and measure the continuity of the signal circuit by:
    1. Probing the wire labeled with the number 1 of the ignition coil's connector (see photo below).
    2. Probing the wire that corresponds to the number 3
      1. -NOTE: This number is embossed on the ignition control module.
  4. The multimeter should register 1 Ohm or less if the wire (circuit) is OK.

No spark from ignition coil for cylinder #4

  1. Disconnect the 4-wire ignition control module connector.
  2. Disconnect the cylinder #4 ignition coil from its 3-wire electrical connector.
  3. Place your multimeter in Ohms mode and measure the continuity of the signal circuit by:
    1. Probing the wire labeled with the number 1 of the ignition coil's connector (see photo below).
    2. Probing the wire that corresponds to the number 4
      1. -NOTE: This number is embossed on the ignition control module.
  4. The multimeter should register 1 Ohm or less if the wire (circuit) is OK.

CASE 1: The multimeter reports continuity in the Switching Signal circuit. This confirms that the ignition control module is bad.

Here's why: So far you have confirmed several important things:

  1. The ignition coil is OK because when you placed it in another location, it sparked (TEST 2).
  2. The connector that feeds the ignition coil (of the ‘dead’ cylinder) is getting both power and Ground (TEST 3).
  3. The Switching Signal circuit (between the ignition module and the ignition coil) is OK.

These three tests results help to indirectly confirm that the ignition control module has failed and is not activating this particular ignition coil.

CASE 2: The multimeter reports NO continuity in the Switching Signal circuit. Repeat the test one more time to make sure of the test result.

If still no continuity exists, then this tells you that there's an ‘open-circuit’ problem in this wire. Repairing this ‘open-circuit’ problem will get the ignition coil working again.

Volkswagen Vehicles:

  • Beetle 1.8L
    • 1999, 2000, 2001
  • Golf 1.8L
    • 2000
  • Jetta 1.8L
    • 2000
  • Passat 1.8L
    • 1998, 1999

Audi Vehicles:

  • A4 1.8L
    • 1999, 2000
  • A8 3.7L
    • 1997, 1998, 1999