I can't get the spark plugs to fire and i have use a multimeter all over the thing, everywhere the haynes manual suggest, but they don't tell me how much voltage the coil wire puts out to the distributor. I just get the same amount as the battery has (12v +- 1). Is that right? I even replace the cap and rotor, still no luck.
Thanks

Rosco,
I swear we're reliving the same night mare in different times of the year.
Just 2 weeks ago I went through the same exact same scenario. When I installed the timing cover, I crushed the wire running from the distributor to the ignition module. This small green and brown wire deliver the pulses to the ignition module, in turn the pulses amplify that signal to the coil, the on/off pulses produce the high voltage spark that your rotor distributes to each of the plugs. Now mine didn't seem to be messed up because when I read the coil resistance in the distributor with a VOM it read fine, but when I tried to get it to fire it would not. Mine started out intermittant, then went to full dead, and wire was only partially grounded through the 12mm bolt on the bottom. Since you had this off, it very could be your problem, trust me. I used a tailight socket on the - side of the coil and the lead to ground, while you're cranking this bulb should flash, dimly, if it doesn't you're not going to run. Seriously check the intergrity of this wire pair, and verify your pulses at the coil, its the only way it will work, Hope this helps...
Chuck....
--
Chuck Jaxel, Pine Hill NJ, Near Philly...

If you`re talking about the HT lead to the distributor cap it`s a bit outside the range of your meter!
Cranking, and with the lead disconnected at the cap end, it should exceed
50,000V yes, 50kV!
Good job you haven`t got a spark, or you wouldn`t still have a meter.
See the FAQ for ingnition diagnostics.
Colin.

Your ignition coil should put out about 30,000-40,000 volts, but very low Amps. 1 Amp would blow your hand off! I don't think you would be able to measure it with a hardware store multi-meter. Try pulling a plug, connecting it to your harness, then grounding it on the engine block and cranking the engine.

I finaly got the thing to run, well almost. I put another battery in it last night and it cranked right up. Then i came back this morning to finish putting the fan and shroud on and it cranked again. It was a little harder this time but it eventually cranked and i ran it for a few minutes. Then i cut it off and it has refused to crank again. The old battery was only pulling 11 volts, the new one pulled 12 volts. So i took the battery out of my Dodge Ram and it pulls 13 volts. It still won't crank. It only wants to pull 11 volts at the coil. What the hell is going on. Why would it pull 13 at the battery and only 11 get to the coil? Help

Rosco, start a new thread. This one's getting long.

So are you saying that you needed a fully charged battery to turn the engine over smoothly? If so, then something is too tight.

Anyhow, start a new thread so that we can go into this further.

This is strange. After replacing the timing belt, the car should have started. Unless you moved something electrical during the initial diagnosis. Maybe fuses (if they're involved)? If the plugs aren'r getting spark, it could be the distributor. Is the rotor turning (cap off)?

You may be able to check for spark from the coil to the block. Did you switch out coils?

Hmm, something is wrong. When I read your note, there were no responses. After posting my answer, there were seven. One, Walrus3's, which matches my suggestions.

You are talking about the high tension wire to the center of the distributor, right?

That one I have never seen a test for. If the rest of the coil works, you should get voltage through the high tension wire.

A bit of basic electromagnetics. The coil works because of the physical law that says: If a magnetic field has a conductor in it, and there is relative motion between the wire and the field, there will be voltage created in the wire for as long as the relative motion continues.

Got that? Aren't you glad I didn't write the texbooks?

So, here's how that applies to the igintion coil. There are two coil of wire in there. One has a huge number of windings, and one - inside the other - has much fewer windings. There is a ratio of the winding count from the one coil to the other.

For the sake of discussion, we'll keep it simple for now. Let's say that the inner coil has 1000 windings, and the outer coil has 5,000. Now, we'll connect a voltmeter across the outer coil, set to read on the DC 250 volt scale.

Next we'll connect the inner coil to a 12volt source, and watch the voltmeter while we make the connection. It Moves! How far? Look at the ratio of the winding counts, it's 5 to 1. So the voltmeter, connected to the coil with the larger number of windings, should spring up to 60 volts, and them drop back to zero.

Why? As the 12v current went into the inner coil, it moved through the windings and a magnetic field was created. Since it was starting at zero and growing, it was moving. When it stopped moving, the voltmeter dropped to zero.

Got that?

Now reverse the conections of the voltmeter, minus where plus was, etc. Then disconnect the 12v source, the needle should again spike to 60 volts and then return to zero. The magnetic field was in motion as it collapsed, thus voltage was created. Why reverse the voltmeter leads? The magnetic field was moving in the opposite direction from the first time so the voltage in the outer (aka secondary) coil will be created in the opposite direction.

So your test reading in the high tension wire will not be the firing voltage unles you connect and disconnted the 12v source. Be greatful your test failed.

In the car coil, There is an enormous number of windings in the secondary coil, so the ratio is like 1 to 4,000. When the ICM does its thing, the coil primary is disconnected just at the right instant, and 12v in the primary creates 48,000 volts in the secondary. That's what goes to the spark plug and fires it.

Aren't you glad you didn't test it?

Believe me, you haven't been zapped until you're sapped by an ignition coil. Older ones, 15 or 20 years back, created 20K to 25K volts. If you got zapped, you jerked and that made you drop whatever you had hold of, not a lot more. The higher powered coils can be fatal.

Now, I don't know what the secondary voltage on a Volvo realy should be. Somewhere in my readings I came across the number at 40,000 volts. High enough for me to stay the hell away from it.

Hope this actually answered your question.

Regards,

Bob

:>)

Hello,

Sounds like your coil has bit the biscuit. From what I understand about ignition systems, the coil's output to the distributor is in the 10's of thousands of volts but with very little amperage, hence why you can still hold on to a plug wire when it is firing. It's not a common failure iten in bricks, so any used one from a scrapper should suffice as a replacement.

Happy Bricking!!!

Richard

87 245 DL 351,000 km
82 242 GLT 121,000 km

http://members.cardomain.com/richink

The output of the coil is high voltage with very low current. The distributer point or the cam switch below the rotor opens and closes on the ground side of the coil primary. The other side of the coil on the primary has 12 volts on it from the battery. Check the 12 volts on the coil red wire and also see if 12 volts positive on the negetive side of the coil black wire switches from 12 volts to zero volts when the engine turns. Place the ground wire of your multi meter to the chassis to confirm this. If you see the 12 volts switch on and off as the engine turns then the coil is ok and the coil is producing the high voltage sent to the rotor then to plugs. Usually coils don't break. Do the old trick of placing a connected spark plug close to the chassis ground and see if you get a spark.

The coil will put out several thousand volts and it can't be read with a multimeter... Unless you have an automotive scope you're just going to have to check for spark by cranking and seeing if you can get an arc to a ground somewhere. If no arc it's a good bet you ain't got no high voltage. Plus, if you are getting no spark out of the coil then the cap and rotor are irrelevant.

Justin B.

Stick a spark plug wire in the top of the coil and put a spark plug on it against the engine. When you crank the engine the plug should fire.
If it doesn't, 500 caps and rotors won't help.
Make sure that your distributor rotor is turning. If not, you have
serious problems and it can't fire until you fix that.
(could be timing belt, etc)

Should be about 12v coming out of the LOW tension side of the coil.

The high tension side (where the fat wire goes to the center of the
distributor) should be around 20,000 volts and you can't measure it
with most meters. That is why you use the spark plug (first comment above).
--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma

Coming of my battery, there is a red wire that goes to a junction box on the fender. Question->Does that junction box power the coil? or where does the coil get its power? THANKS, as my coil works some times and some times not, but the moter will crank and coil wont spark. THANKS
--
Kevin * HONDA spanking,1985 240DL * VOLVO ON!!!!

Thank you for the good posts. The rotor in the distributor does spin when the motor turns, and the little positive pole on the coil pulls 12volts. I will try the plug wire on the coil and ground the spark plug and see if that will fire. The volvo is sitting in a parking lot on the other side of town so I will have to make another trip over there to see if that will work. Should the coil pull voltage from the battery only will the motor is turning or all the time while the key is turned to on? I have by passed the balast resistor because it was very hot. Is that a problem? I also have none of the belts on it from when i changed the timing belt, except the timing belt of course. Would that change anything?
Thanks