Question about Ford Cars & Trucks

3 Answers

How do i check the trigger side of the coil with a test light? can you send me a wiring digram?

1975 Ford F350 360 engine there is voltage at the + side on the coil but i didn't check the - side how do i check the - side? there is know spark at the secondary coil wire.

Posted by on


3 Answers

  • Level 2:

    An expert who has achieved level 2 by getting 100 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.

  • Expert
  • 221 Answers

On a standard external coil, you can use an incandescent test light. ground the test light lead. key on engine off both terminals of the coil should be HOT (light on when you touch either). If the ground is being sent by the module (or PCM on cars where the module is part of the main computer), then when the engine is running or cranking, the light should FLASH if you are holding it to negative while the engine is cranking or running. (Note, it will flash very fast when the car is running, so fast it may look solid if you dont look very carefully). That flashing is the trigger signal pulse grounding the coil to fire it for each cylinder. That in itself is only 1 test, you wont know if its enough ground, too long or short, or if the coil is functional. Its a very simple test using the cheapest of equipment. Proper testing using better equipment will tell you alot more info. But that will tell you if your ignition module is trying to fire the coil. Other issues like crankshaft sensor, theft system, or ignition switch crank-only outputs can cause no spark cranking and are harder to diagnose.

Posted on Jun 26, 2018

  • Joe Russell Jun 26, 2018

    i am working on a 1975 Ford F350 360 engine 1t have a ignition module, pickup coil i don't think it have a computer and crankshaft sensor do the ignition module fire the coil or the pickup coil fire the coil ignition? i hope you can help me find out why there is no spark at the ignition coil second wire and spark plug wire. will a timing chain cause no spark?

  • Robert Wood
    Robert Wood Jul 09, 2018

    The ignition module is a computer .


  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.


    Visited the website for 20 consecutive days.

  • Master
  • 280 Answers

Check for voltage at the negative (-) side when the positive (+) side has power. There should be voltage on both. If not, you have a bad coil

Posted on Jun 24, 2018

  • Joe Russell Jun 26, 2018

    There is voltage on both side of the coil i check for a trigger signal on the (-) side of the coil with a test light i connect the clip end of the test light to the (-) post on the battry and the pointer end of the test light to the (-) side of the coil and crank the engine look like the test light was blinking did i hook the test light up right? i hope you can help me find out why there is no spark at the coil secondary wire. what i need to do next to fix the problem?

  • T Wolgamuth
    T Wolgamuth Jun 26, 2018

    If you hold (or prop is better so you don't get shocked) the center coil wire close to grounded metal (within 1/4") (or just plugged into a grounded spark plug) and turn motor so that the light is blinking as you did above, you should be getting a spark every time the test light goes out. If it's blinking and your not getting a spark, you have a bad coil. Can't think of what else it would be.


  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • Ford Master
  • 4,927 Answers

A test light clipped to battery positive and the probe tip touched to ignition coil negative while cranking the engine over will blink if receiving pulse signal .

Posted on Jun 26, 2018

6 Suggested Answers

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi there,
Save hours of searching online or wasting money on unnecessary repairs by talking to a 6YA Expert who can help you resolve this issue over the phone in a minute or two.

Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.

Here's a link to this great service

Good luck!

Posted on Jan 02, 2017

  • 4 Answers

SOURCE: engine shut off while driving, cranks over.

Hi, I had the same problem, no spark. I check coil it was good, check the injectors for pulse they are fine, I checked the four wire harnes conected to the distributor are fine, I check resistance at the power transistor in top of the air filter assembly and it was wrong, I just replaced the power transistor and the car is running good again.
I hope this help you.

Posted on Oct 21, 2008

  • 5487 Answers

SOURCE: Check engine light will not come on when key is

bring coil to parts place and testit--get car scanned by mobile mechanic

Posted on Oct 20, 2010

  • 547 Answers

SOURCE: I have a 1995 jetta

This sounds like a bad crank position sensor. The crankshaft position sensor on the AAA engine is located on the "intake" side of the engine block, near the flywheel. Pull that sensor out and see if Auto Zone has a test procedure for it. There is also a chance your ECM fuse is blown. If your service engine soon light comes on when you turn the key on (not starting it) then the fuse is good.

Posted on Dec 05, 2010

  • 5332 Answers

SOURCE: Weak or no spark - won't start.

If the coil cannot produce enought spark to jump at least a one inch gap, replace it. Is the coil internal or external to the distributor?

I’m happy to assist further over the phone at

Posted on Aug 05, 2012

  • 4927 Answers

SOURCE: why there is no spark from the coil wire when cranking why?

If you hook a test light to battery positive and touch negative terminal on coil and crank engine over does light blink ?

Posted on Jun 22, 2018

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

2 Answers

Why there is no spark at the ignition coil?

Switch out a known good coil if you have one . If you have power and a switching cranking signal to the coil I would swap the coil out .

Jul 02, 2018 | Ford Cars & Trucks

2 Answers

Why there is no spark from the coil wire when cranking why?

I have no wiring info for your model year. With key on both positive and negative at the coil, are hot, correct?
Do you have tfi module on this vehicle?

Jun 22, 2018 | Ford Cars & Trucks

1 Answer

1991 Dodge Dakota 2.5 liter 4 cyc blew fuse I replaced fuse no start have replaced pick up coil ,coil,plugs ,wires, cap,rotor,fues all good still no spark and no start helllppppp please!!!!!

Make sure battery has a full charge. Did you check primary voltage to ignition coil, engine cranking, dark green wire with orange tracer? Use a test light, is it hot? The voltage comes from asd relay, check voltage and ground circuits. The load side of relay is that line with arrowhead, that circuit is fuse protected and hot all the time. The control side of relay is the left side in diagram, has to have voltage and ground. The voltage appears to come from ignition switch on or cranking. Grounded by computer.
The distributor has a sensor in it that sends rpm signal to computer, w/o that signal the computer won't ground the asd relay and you get nothing. The asd relay sends voltage to several systems. Just my opinion. Any applicable trouble codes?
ignition coil primary voltage-1anaufhylhxspep0buiq5jhw-2-0.jpg

May 29, 2017 | Dodge Cars & Trucks

1 Answer

How do i check the trigger side of the ignition coil? what is all the things that will cause no spark at spark plugs boot?

What are the fault codes in memory for this problem, if you haven't run that test borrow an OBD2 code reader and do the test.

Dec 02, 2016 | GMC Cars & Trucks

1 Answer

Engine no spark

If the engine has no spark, check for voltage at the coil positive terminal when the ignition key is on.
If there is voltage, the problem is on the trigger side of the coil (pickup, crank sensor, ignition module or primary wiring circuit).
If there is NO voltage at the coil, the problem is on the supply side (the ignition switch or ignition wiring circuit).

Apr 22, 2012 | 1998 Dodge Ram 1500 4WD

1 Answer

1996 ford explorer no start problem(engine cranks) hooked snapon redbrick scanner w/ no communication, also no self test. power to and thru pcm relay, power to fuel pump relay but relay not...

I'm not a certified anything. Don't mind talking to you, though.
In the olds days to see if computer is awake, turn on the key, check ref voltage to any sensor that uses a ref voltage. If no ref voltage anywhere, have to check out the computer and wiring circuits, voltage and ground. I'm sure you know at the datalink connector, pin 16 is voltage and pins 4 and 5 are grounds.
Just about any relay that you can unplug, if you use a jumper wire between terminals on load side of relay, in diagram, the load side is that line with arrowhead, it will send voltage to anything the relay controls, the you check control side of relay, that coil symbol in diagram, for voltage and ground.
Just my opinion.

May 25, 2017 | Ford Explorer Cars & Trucks

1 Answer

I have 3.0 engine only firing on 3 cylinders with ign on unplug coil wire at coils with kight all light one side put test light on other wire turn over engine wont blink thanks

If I've interpreted what you've said correctly on one side of your engine you test light lit up and on the other side nothing happened. With the key in the on position your voltage at each ignition coil should be at/near/above 11.5volts on a charged 12 volt battery. You'll need a multimeter to perform these function tests. First test voltage as I mentioned if one side is still dead do a resistance check as well and if it is an open circuit with no resistance that means you have either a wiring problem in that harness or a problem with those wires going into the ecu whether it be a loose/damaged terminal connection or maybe even a problem with the computer itself. If you haven't checked your spark plugs already I would do that first, if they are fouled then that may have been a contributing factor as well and if so replace them (make sure they're gapped to specification) and then try the suggestions I listed above. Let me know what you come up with and if you need further help

Feb 02, 2011 | 2005 Ford Escape

1 Answer

In my 2002 dodge durango myh check engine light is on and I took it to auto zone to have them check the engine codes. Upon the completion of the test I got 4 engine codes P300 P301 P302 and P0442. The...

Do you know how to test electrical circuits ? Is the PCM - engine computer controlling the coils ? Test with a test light ! One side has B+ voltage the dark green with orange stripe wire ,the other goes to the PCM , which will suppy a ground when triggered . You can test this with a test light . or you can buy a noid light at the parts store . If you replaced the coil an spark plug an that code comes back ,could have a burnt driver inside the computer , test it first !
How to test computer transistor driver without scan tool

Jun 21, 2017 | 2002 Dodge Durango

2 Answers

Getting 12V on the ground wire to the coil. Any

the coil has two wires. one side is hot 12 volts the other side is the side that is pulsed to ground to create the magnetic field to induce high voltage.. with the key on not running you should see voltage on both wires... disconnect the plug from coil and recheck you will have power only on one wire that is the hot wire.. hook back the plug now take your test light ground clip and clip it to the positive terminal on battery. then back probe the wire to be pulsed.. have some one crank jeep and you look at test light.. looking for kinda dimm flash... if so that tell you you should have spark if not the bad coil.. if you don't see flash then probable bad pick up/... let me know

Sep 01, 2009 | 1985 Jeep CJ7

2 Answers

I have a 2001 ford f150 4x4 .6 triton misfiring

The way that I usually test coils or plug wires is to use an insulated plug wire puller and pull each plug wire (one at a time) to see if the engine speed changes. If you disconnect one wire and nothing changes, you probably have found the defective wire or coil.
You can also use a plug wire tester (neon type) to see if you have a spark. Can also hook up a timing light to a coil wire and it will trigger if coil is good. It will not work if coil is bad.

Apr 27, 2009 | 2001 Ford F150 Styleside SuperCrew

Not finding what you are looking for?
Cars & Trucks Logo

Related Topics:

730 people viewed this question

Ask a Question

Usually answered in minutes!

Top Ford Experts


Level 3 Expert

83481 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22393 Answers

gerry bissi

Level 3 Expert

4387 Answers

Are you a Ford Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides