I have the manuals but do not understand how to test it with a multimeter.

The manual states: Use High Scale - Should read Very High (Infinite).

What?

What would I set the Multimeter to in order to test the coil?

Ohms (resistance). If your meter has more than one Ohm setting use the highest

You are looking to measure units of resistance called ohms.
Look up the spec. The primary will usually read a high resistance like a few thousand ohms while the secondary will read a low resistance.
Just set your multimeter to the ohms scale for a reading just higher than what you would expect to read . Now touch the two multimetter wires together. If you are set properly they always read zero on any scale.
The primary is measured at the coil btween the ground - pin and the + pin. The secondary is measured between the ign coil tower and ground.

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[This message has been edited by Dennis LaGrua (edited 06-02-2010).]

I absolutely do not get it. Is it because I have a digital multimeter and not an ohmmeter?

The fiero manual instructions state:

Using the ohmmeters high scale, hook up the ohmmeters leads as shown.

High scale???... choose 2000k on the multimeter?

Then the instructions state: The ohmmeter should indicate a very high or infinite resistance value.

So... what is this value I am supposed to be looking for? ( 0... 360... 480...a gazillion ??? )

Since I don't know your multimeter settings, I would recommend you turn the switch to "ohms" and set the meter to "R X 1,000" and measure across the coil windings. If you get no reading, turn the meter to "R X 10,000" and you should get either a small reading or it will not read anything--no resistance. Take care to not put your fingers on the test leads while you're measuring because you can measure your body resistance in the megohms (millions of ohms) range and that will affect the accuracy of the reading of the coil.

Dennis LaGrua's method is the same as what I just wrote but maybe this can explain it in more detail.

Edit: If you can post a picture of your multimeter, I think one of us can give you better advice. Not all meters are the same or created equal.

[This message has been edited by starlightcoupe (edited 06-02-2010).]

Here is what I am using.

I am wondering what I would look for when trying to determine what a high or infinite resistance value is on this meter?

If I had a target or specified range per se to determine if the coil is good or bad.

[This message has been edited by Knucklebuster (edited 06-02-2010).]

The image broke apart even in Photoshop but hopefully, I can make out what your meter looks like. Turn the switch to the highest number(it looks like it may be where I show it on the picture below)and measure across the coil using the directions Dennis LaGrua and others (including me) gave you. This meter isn't the best and is a compromise but it should be adequate.

An automotive coil is either a traditional transformer or an autotransformer but in either case, a small voltage on the primary will be stepped up to a much higher voltage when a voltage is quickly applied and removed from the primary. If you get a small reading on one of the terminals, you're reading the primary and not knowing the resistance of the secondary, I would guess that it would be in the thousands or millions of ohms of resistance.

Hope this helps.

Thanks, Starlight.

I get readings for sure - I just don't know what they represent.

Following the diagram above, these are the readings I get:

Step 1 = 8 on the meter. (Should be Infinite/very high)

Step 2 = 0 on the meter. (Should be low/zero)

Step 3 = 8 on the meter. (Should not be Infinite)

I am stumped as to what "should not be infinite" means... and what does that look like on the meter?... and is 8 very high/infinite?

I will see if the parts store can test it and keep it as a back-up if it is good.

I appreciate the time and the responses.. but I think I will just get another coil and be done with it.

From what you wrote, I think your coil is good. "Infinite" means that there is no resistance--which would mean the coil is defective probably caused by a broken or burned wire. The number "8" probably is 8000 ohms of resistance. The "zero" reading means that there is no resistance which is more than likely what you're reading across the primary. You'd have to move the meter switch to a lower range (100 ohms, for example) to measure the primary.

A new coil may be a good thing to have.

Infinite is the reading you get before the leads are hooked up to anything.


Actually I am thinking the 8 you are describing is a sideways 8? That is what the meter reads when the leads are not hooked up to anything? What the meter says when the leads are not hooked up = infinite. Test #3 fails if you get infinite. You stated you get what I am thinking is infinite. That means your coil failed the test and is bad.

That's assuming that your "8" means infinite.

[This message has been edited by phonedawgz (edited 06-02-2010).]

Thanks for the research phonedawgz!

I just got back from the parts store and exchanged it for a new one.

Unfortunately - this means I have an electrical issue since the one we were testing was only a month old.

I suspect my brand new alternator is shot - as it is running at about 15.7 when I first crank up the car (but then goes to the normal 14.6 range)

And I have an 87 Gt auto.... the absolute worst model to have to swap out an alternator. The absolute worst.

If it drops to 14.7 shortly I don't think its bad.

Yea... it's a strange issue.

When I bought the car, the volt gauge was reading high.. just next to the red.

I thought this alternator fried a new battery so I replaced it with a new alternator.

When I fired it up - the volt reading was still the same on the new alternator. So I tested the voltage at the alternator.

15.7 when it starts ... then it gets down to the 14.6 after a few minutes of driving.

In fact, I usually turn the vent fan on high as soon as I start it up just to force the voltage down slightly.

Since replacing the alternator, I have had to replace an ignition module (old one).... and now the new ignition coil. Had to get towed home twice in two months.

So.... I am weary to drive the car until I figure out WTH is going on.

Hi Knucklebuster, read your last post. An alternator will compensate for the electrical load in the car, so when you run the fan on hi, it increases the load, and a healthy alternator will charge at a higher voltage. Only when the load on the system goes down, will the alternator (through the action of the voltage regulator) reduce the charging voltage. What you are doing, though it seems to make sense, is making the alternator work harder. Assuming that the system voltage goes down while the fan is still on hi, I would look elsewhere for another component that is drawing a lot of power at startup.
Angelo

lookn at your alternator I would go out and test the voltage at the battery before startup after sitting for 24hrs. U could have a drain thats pulling your battery down and your alternator is spiking at startup to recharge the battery.

I post file often for problems like yours:


Your’s could be a common problem and don’t cost anything to check.
Try this:
Watch the tach when cranking if it don’t move you're not getting pulses from the distributor. If so, it could be a faulty module in it or more likely simply corroded connectors at the base of the distributor. Reseating those connectors a few times could clean the pins some and also do the same to the connectors on the coil etc. These cars are old, and old connectors corrode. Such can also manifest itself as intermittent misfires, and engine cutouts.

BTW: lots of folks keep replacing modules and coils thinking they are bad because the new ones FIX the problem, when in actuality the fact that they simply unpluged the connectors and repluged them into the new unit cleaned the contacts enough to make it work again, at least for a while. It's smart, to replace those old connectors with new ones.
BTW: Cliphouse has those connectors

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Thanks guys... I started a new thread relating to this voltage issue.