TEST 1: Testing The Power Circuit
We'll begin by checking that the ignition control module is receiving 12 Volts. You can use a digital or analog multimeter or even a test light for this test. I do recommend using a wire-piercing probe to accomplish all of the tests in this article. (to see what this tool looks like, go here: Wire Piercing Tool). Whatever method you use, the key here is to be careful. Remember to use common sense and take all safety precautions.
Remember, although the photos in this article show the ignition module and coil pack assembly off of the car, these tests are on-car tests. DO NOT remove the ignition module and coil pack assembly from the vehicle to test it.
OK, these are the test steps:
- 1
Put the multimeter in Volts DC mode.
- 2
Disconnect the connector labeled with the number 1 in the photo above.
- 3
Connect the black multimeter test lead to the battery negative (-) terminal.
- 4
Probe the pink (PNK) or pink with black stripe (PNK/BLK) wire of Connector 1 with the red multimeter test lead and a suitable tool.
The PNK wire (or PNK/BLK) connects to the female terminal labeled with the letter A in the image above. - 5
Turn key ON with the engine OFF.
- 6
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 showed 10 to 12 Volts. This is the correct and expected test result and it tells you that everything is OK on the Power Circuit.
The next step is to go to: TEST 2: Testing The Ground Circuit.
CASE 2: Your multimeter DID NOT show 10 to 12 Volts. This test result tells you that the ignition control module is not receiving power.
Without power, the ignition module will not function and cause an engine no-start problem.
The most common cause of this missing voltage will be a blown fuse. Check and repair or replace as necessary. The vehicle should start now.
TEST 2: Testing The Ground Circuit
In the previous test step (in the previous page), you verified that the ignition control module is indeed receiving 12 Volts. Now, I'm gonna' show you how to test its Ground circuit. Again, as in the last test step, I recommend that you use a wire piercing probe to accomplish this one.
Although the following test steps are explained using a multimeter, you can use a test light instead. OK, the ignition control module receives GROUND on the B circuit of Connector 1 (see the photo above).
Let's get started:
- 1
Put the multimeter in Volts DC mode.
- 2
Disconnect the connector labeled with the number 1 in the photo above.
- 3
Connect the red multimeter test lead to the battery positive (+) terminal.
- 4
Probe the black with white stripe (BLK/WHT) wire of Connector 1 with the black multimeter test lead (and a suitable tool) .
The BLK/WHT wire connects to the female terminal labeled with the letter B in the image above. - 5
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 is the correct and expected test result and it confirms that the Ground circuit is OK.
The next step is to verify that the ICM is receiving the crankshaft position signal. Go to: TEST 3: Testing For The Crankshaft Position Sensor Signal.
CASE 2: Your multimeter DID NOT register 10 to 12 Volts. This test result tells you that the ignition control module is not receiving Ground. Without Ground, the ignition module will not work.
With this result, you have now eliminated the ignition module itself as the cause of the no-start problem.
The most likely cause of this missing Ground is an open-circuit problem in the wire.
Repair the cause of the open-circuit problem and retest. The car or truck (Isuzu Rodeo or Trooper) should start once Ground is restored to the wire.
