Technical Car Experts Answers everything you need: THERE is NO 12 VOLTS to the ignition COIL WITH THE KEY ON?

Sound like a ground problem; the fastest way to identify the Power and Ground Circuits is using a wiring diagram. If you don't have one you'll have to find out by trial and error as you probe each circuit.

The power circuit is tested with the Key On and Engine Off. Place one end of your multimeter or Test Light on the Battery Negative Terminal and with the other end, probe the Power Circuit. Turn the Key to the Run position. If the Power Circuit is OK, the Multimeter will show 12 Volts or the Test Light will light up. Here are the possible results:
* You got 12 Volts on the Power Circuit
Good, this is a good sign. The next step is to check the Ground Circuit of the Coil on Plug connector that you're testing.

* No Power in only one Ignition Coil
Without 12 Volts, the Coil-on-Plug Ignition Coil will not work, thus you have just eliminated that specific Ignition Coil as the source of the fault. Replacing the Ignition Coil with a new one will only be a waste of time and money since, without Power the new one will not Spark.
Since the Power Circuit is shared by all of the coils on the majority of Coil-on-Plug Ignition Systems. The most likely cause will be an open short in that Ignition Coil's Power Circuit.
You'll have to consult your Repair Manual's wiring diagrams to make sure how everything is wired up.
After repairing the short, re-do the Spark Test to verify the Ignition Coil is now working.

* No Power at any Ignition Coils
The fuse or relay that supplies this voltage is blown or BAD.
You'll have to consult your Repair Manual's wiring diagrams to see where this fuse and/or relay is located and replace as necessary.
After replacing the blown fuse or the defective relay. Retest the Ignition Coil.

Them, the Ground Circuit is tested with the Key On or Off. It doesn't matter because this is a Chassis Ground. Place one end of your multimeter or Test Light on the Battery Positive Terminal and with the other end, probe the Ground Circuit. If the Ground Circuit is OK, the Multimeter will show 12 Volts or the Test Light will light up.

* You got Ground
Good, now the next step is to verify that the Coil-on-Plug Ignition Coil is receiving the Triggering Signal. This info belongs to the next section of this article.

* No Ground in only one Ignition Coil
Without this Ground, the Coil-on-Plug Ignition Coil will not work, thus you have just eliminated that specific Ignition Coil as the source of the fault. Replacing the Ignition Coil with a new one will only be a waste of time and money since, without Ground the new one will not Spark.
Since the Ground Circuit is shared by all of the coils on the majority of Coil-on-Plug Ignition Systems. The most likely cause will be an open short in that Ignition Coil's Ground Circuit.
You'll have to consult your Repair Manual's wiring diagrams to make sure how everything is wired up.
After repairing the short, re-do the Spark Test to verify the Ignition Coil is now working.

* No Ground at any Ignition Coils
This usually happens thru' human error in most cases and is a very rare thing. Usually the engine was replaced and this ground was not re-attached.
You can Ground this circuit with a jumper wire. Jumpering to Ground just one Coil-on-Plug Ignition Coil should provide Ground to all of them (consult your Repair Manual's Wiring Diagrams to be sure).
With this jumper wire to Ground attached, crank the vehicle.
If in fact the Ground Circuit does have an open short, this (the jumper wire to Ground) should make the vehicle start, or at least get the Ignition Coil to Spark.
Repair the open short and retest for Spark or retry starting the vehicle.

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