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The only safe way to test for spark is to use a spark plug tester tool. If a coil problem is suspected, measure the coil’s primary and secondary resistance with an ohmmeter. If either is out of specifications, the coil needs to be replaced. A coil can be easily bench tested with a digital 10 megaohm impedance ohmmeter.
The only safe way to test for spark is to use a spark plug tester tool. If a coil problem is suspected, measure the coil’s primary and secondary resistance with an ohmmeter. If either is out of specifications, the coil needs to be replaced. A coil can be easily bench tested with a digital 10 megaohm impedance ohmmeter.
The power from the ignition switch need to go to the plus side of the coil and the negative goes the the distributor on a 12v system. That should be opposite what it was on a 6v positive ground.
A typical value would read 0.4 – 2 ohms.
Testing Procedure
Scratch the lead on the plate to ensure it’s in contact. Touch the meter’s black lead to the metal coil housing and watch the meter. If the meter’s display indicates a value of 2.5 to 5 K ohms, then the coil is good.
Electicity Goes In
The electrical system in your vehicle works on 12 volts, so every component must be based on 12 volts, as well. There is a wire connected to the ignition coil (known as a “hot wire”) that carries the 12 volts into the coil itself.
Loss of spark is caused by anything that prevents coil voltage from jumping the electrode gap at the end of the spark plug. This includes worn, fouled or damaged spark plugs, bad plug wires or a cracked distributor cap.
Yes, if the points are open and/or the electronic module is NOT CLOSED then you will measure battery voltage on both the coil (+) and coil(-) terminals. Since there is no current flowing through the coil (no path to earth) then both sides of the coil will be at the same potential.
Yes, you should get 12V at either end of the wire. This is always true if the wire is good.
Connect your multimeter to the positive terminal or pin of your coil, and to the high output terminal that goes to the spark plug. Most ignition coils should have a secondary resistance falling somewhere between 6,000 to 10,000 ohms;however, refer to manufacturer specifications for the correct range.
You should have a resistance reading of at least 3-4.5 ohms. A bad coil will show a higher reading then 3-4.5. Next, place the red or black lead from the meter to the centre of the coil , and to either one of the terminals positive or negative. You want 9500-10000 Ohms, a little less is ok but no more.
The normal, acceptable range for a standard 12-volt car is 1.5 to 1.7 Ohms.
The simple answer is no, the coil case does not have to be grounded for the ignition to work properly.
The battery provides low voltage electricity to the ignition coil. … That moves other distributor parts that cause the ignition coil to pulse, and sends the electricity down each spark plug wire in order. The power travels down the spark plug wires to the spark plugs and causes sparks.
Use a “safety” screwdriver, one with a rubber or plastic handle cover. Put the screwdriver in the unattached end of the plug wire, and hold the rest of the screwdriver near a metal surface. Get someone to attempt to start the engine and you should see a strong blue spark jump from the plug to the engine.
It is usually located in the fuse and relay panel beneath the hood, and is responsible for providing power to the vehicle’s ignition system, and some of the fuel system’s components. Usually a bad or failing ignition relay will produce a few symptoms that can notify the driver of a potential issue.
Bad grounds can cause no spark issues though. It can cause the ground to ground through the ecu frying it. If you get a single spark when turning on the ignition then nothing when cranking it’s the ecu. It’s a really good idea to go over all your grounds on a regular basis anyway.
Locate the positive or power wire attached to the engine coil. Check for power using a test light. If this wire has no power, then your ignition coil is not receiving current. You should check the wiring from your ignition switch to the coil for breaks in the wire and repair them.
One end of the secondary is grounded (the ‘negative’ terminal), the coil produces the voltage (the ‘battery’) and the output goes out the ‘positive’ terminal to the spark plug, where it jumps the spark gap and returns to ground, completing the circuit.
For positive ground the “+” terminal goes to the distributor (to be grounded on the engine block). For negative ground the “-” terminal goes to the distributor (to be grounded on the engine block).
Re: Coil has constant power
Yes, the coil is always connected to the battery. It’s no more of a problem for the wires IN the coil than it is for the wire ON THE WAY to the coil, as long as there is no current flow.
When you hold the coil so the plug wires are to the left (like standard shovel or evo mounting, mounting holes at the rear), the negative side is on the top and the positive is on the bottom.
To test your ballast resistor you need an ohm meter or multimeter set to ohms. Remove the connectors from both sides of the resistor. The ohms should read between 1.8 and 5 ohms. You should be getting 9 volts to the positive side of the coil.
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