How To Test The 1.8L VW Ignition Control Module and Ignition Coils

TEST 5: Testing The Continuity Of The Activation Signal Circuit

Alright, this is the last test you need to perform to confidently conclude the non-sparking ignition coil as being bad.

What you'll need to do is make sure that there's continuity in the circuit that feeds the activation 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.

NOTE: The numbers are embossed on the ignition control module.

OK, these are the test steps:

1. 1

   Disconnect the 4-wire ignition control module connector.

2. 2

   Disconnect the ignition coil that did not spark from its 3-wire electrical connector.

3. 3

   Place your multimeter in Ohms mode.

4. 4

   Choose the one that applies:
   
   Cylinder 1 Ignition Coil: Test for continuity between:
   
   The terminal that connects to wire number 1 of the ICM connector (see photo above).
   
   The terminal that connects to wire number 1 of the ignition coil connector.
   
   Cylinder 2 Ignition Coil: Test for continuity between:
   
   The terminal that connects to wire number 2 of the ICM connector (see photo above).
   
   The terminal that connects to wire number 1 of the ignition coil connector.
   
   Cylinder 3 Ignition Coil: Test for continuity between:
   
   The terminal that connects to wire number 3 of the ICM connector (see photo above).
   
   The terminal that connects to wire number 1 of the ignition coil connector.
   
   Cylinder 4 Ignition Coil: Test for continuity between:
   
   The terminal that connects to wire number 4 of the ICM connector (see photo above).
   
   The terminal that connects to wire number 1 of the ignition coil connector.

5. 5

   The multimeter should register 1 Ohm or less if the wire (circuit) is OK.

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

CASE 1: The multimeter reported continuity. This is the correct test result and it tells you that the wire delivering the ignition coil's activation signal is OK.

You can conclude that the ignition coil is bad and needs to be replaced if you have:

1. Confirmed the ignition coil is not sparking (TEST 1).
2. Confirmed that the ignition coil is getting both power and Ground (TEST 2 and TEST 3).
3. Confirmed that the ignition coil is getting an activation signal (TEST 4).
4. Confirmed that the ignition coil activation signal wire has continuity (this test section).

CASE 2: The multimeter reported NO continuity. Repeat the test one more time to make sure of the test result.

If still no continuity, 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.

Article Conclusion

A bad ignition control module causing a misfire condition (and one of the following diagnostic trouble codes: P0301, P0302, P0303, P0304) is a problem I have encountered quite a bit on the 1.8L VWs.

In the beginning, I would diagnose the issue with my oscilloscope (which is the most accurate way of doing it, but a little more time consuming). But, like I mentioned before, since this is a very common problem with this type of ICM in the 1.8L VWs, I was able to forgo the oscilloscope and test them the way I've described in this tutorial with a lot of success.

The most important things to remember (and to successfully diagnose the issue) is to:

• First: Identify the misfiring cylinder with a cylinder balance test (even if you do have a misfire code).
• Second: Test for spark with a dedicated spark tester.

Hopefully this tutorial helped you nail down the misfire problem, if it was being caused by a bad ignition control module or a bad ignition coil.