TEST 4: Testing The Ignition Coil For Spark
So far the test results from TEST 1 and TEST 3 have confirmed that:
- There's no spark coming out of any of the 8 spark plug wires (TEST 1).
- The ignition coil's high tension wire is not sparking (TEST 3).
The next test is to check for spark directly on the ignition coil's tower. As you can see in the photo above, I have removed the high tension wire from the ignition coil and I've connected the spark tester to the ignition coil's tower (with a piece of vacuum hose).
If the spark tester sparks when you crank the engine, then the ignition coil's high tension wire is bad and it needs to be replaced (since it has stopped transmitting spark and is causing the no-spark no-start problem on your 5.2L Jeep Grand Cherokee).
If you don't get spark from the ignition coil's tower, then your next step is to go to TEST 5.
These are the test steps:
- 1
Disconnect the high tension wire that connects to the ignition coil.
- 2
Connect the spark tester to the ignition coil's tower (see photo above).
- 3
Ground the spark tester directly on the battery negative (-) terminal with a jump start cable.
- 4
Have your helper crank the engine.
- 5
The spark tester should spark.
Let's examine your test result:
CASE 1: The spark tester sparked. This is the correct test result.
With this test result you can conclude that the ignition coil is good. Also, this test result confirms that the ignition coil's high tension wire is bad if your test results have confirmed:
- That the 8 spark plug wires ARE NOT sparking (TEST 1).
- That the ignition coil's high tension wire did not spark in TEST 3.
- That the ignition coil does spark (this test section).
CASE 2: The spark tester DID NOT spark. The next test is to make sure that the ignition coil is getting 10 to 12 Volts.
For this test go to: TEST 5: Making Sure The Ignition Coil Is Getting 12 Volts.
TEST 5: Making Sure The Ignition Coil Is Getting 12 Volts
As you're probably already aware, the ignition coil has a 2-wire connector.
On the 1993-1995 5.2L V8 Jeep Grand Cherokee, the wire that delivers 12 Volts to the ignition coil is the dark green with black stripe (DK GRN/BLK) wire of the connector.
On the 1996-1998 5.2L V8 Jeep Grand Cherokee, the wire that delivers 12 Volts to the ignition coil is the dark green with orange stripe (DK GRN/ORG) wire of the connector.
Also, the ignition coil connector on the 1993-1997 Grand Cherokee differs from the ignition coil connector on the 1998 Jeep Grand Cherokee.
Photo 1 of 2 above, is of the ignition coil's connector on the 1993-1997 5.2L Jeep Grand Cherokee.
Photo 2 of 2 is of the ignition coil's connector on the 1998 5.2L Jeep Grand Cherokee. Regardless of the difference of the connectors, the test is performed in the same way.
We'll use a multimeter to check for these 10 to 12 Volts while cranking the engine.
CAUTION: To check for the presence of 12 Volts you must crank the engine. Be careful and take all necessary safety precautions!
These are the test steps:
- 1
Select Volts DC mode on your multimeter.
- 2
Connect the red multimeter test lead (and the appropriate tool) to the terminal labeled with the number 2.
NOTE: Avoid probing the front of the terminal or you run the risk of damaging it. Use a back probe or a wiring pierce probe to test for the presence of 12 Volts. - 3
Connect the black lead of the multimeter to the battery (-) negative terminal.
- 4
Have your helper crank the engine while you observe the multimeter.
- 5
You should see 10 to 12 Volts on the multimeter.
Let's analyze your test result:
CASE 1: 10 to 12 Volts are present. This is the correct test result and it tells you that the ignition coil is getting power.
The next test is to see if the ignition coil is getting an activation signal on the terminal labeled with the number 1. For this test go to: TEST 6: Testing The Ignition Coil's Activation Signal.
CASE 2: 10 to 12 Volts ARE NOT present. If the ignition coil doesn't get power, it will not fire spark.
This lack of spark will be caused by one of the following:
- An open-circuit problem in the DK GRN/ORG (or DK GRN/BLK) wire between the ignition coil's connector and the auto shutdown relay (ASD) relay.