[chubaka]

Hello and Greetings to All,
I am new to this forum and this is my first post. My son should be doing this but he is out in the yard, during a snow storm, contemplating why there is no spark from the coil of his 91 Honda Civic.
This car cannot break down near home - it always does so, one other time, 45 miles away on the way back from my sons place of employment. Last time after much unnecessary work and getting parts from the bone yard, we found the problem to be the "Attack of the Main Relay". This we found after changing the fuel pump and changing components of the distributor without success. At the yard we picked up a few Main Relays, what I think is an ignitor (shaped like a large book of matches and having male electrical contacs on it - If this is not the Ignitor please advise!), but couldn't find a coil. When we located the Main Relay we changed it with one that we had bench tested all circuits so we knew it was good - problem solved.. This time when I got to his location I noticed that the plastic shaft of the rotor had come free from the metal insert and it must have done some spinning because the set screw was not visible until I broke away the plastic and pulled the metal shaft insert and installed a brand new rotor. My son kept the extra parts in the Honda and changed the Main Relay while he waited for me to arrive. He also, in an attempt to remove the rotor, set off a spark in the distributor with a screw driver. He doesn't remember if he had the ignition key on at the time. After a couple of hours tinkering with this and that I decided that we were not going to fix it on location so I towed it home.
The situation is as follows: Main Relay switch is good, I changed what I thought was the ignitor - shaped like a large book of matches with male terminal connectors on it, still there is no spark from the coil. The coil has two wire connections at the top - I ran a continuity check between these two while connected and there is no continuity (I don't really know if this reveals anything about the coil). I do not have a scope only a volt/ohm meter and the usual tools for auto repair. Any and all "spark getting" suggestions will be deeply appreciated. Is there any way to troubleshoot the coil, the ignitor?

[thebriggsdude]

I will ask this as well, how many miles. Hondas have problems with belts and the electricals for those models. Didn't make any noise before it stopped working did it

[labman]

The coil is definitely bad. The 2 terminals are the primary winding, and should show a small resistance. One should be hot when the key is on, and the goes to the distributor or ignition module.

[chubaka]

i will ask this as well, how many miles. hondas have problems with belts and the electricals for those models. didn't make any noise before it stopped working did it

Thanks for your reply. My son said he did hear a low sounding noise but cannot remember what kind of sound it was just before it died. We figured it was the rotor separating from it's grommet and spinning around - there seemed to be melted plastic on the rotor's shaft. The car has 2K+ miles but was acquired as a gift from a friend who took pretty good care of it and might have changed the timing belt , etc. as needed. Later we can call her to see if she remembers... Do you know if the ignitor is what I described above?

[chubaka]

The coil is definitely bad. The 2 terminals are the primary winding, and should show a small resistance. One should be hot when the key is on, and the goes to the distributor or ignition module.

My thanks to you also for your reply. Is it necessary to have the key turned on and both wires connected to the coil when testing it for continuity? My son thinks I made him turn the key on but I don't remember that for sure.
Is the ignition module the group of wires that come from what looks like a condenser and seem travel under the distributor? These are the wires that hook up to what I believe is the Ignitor - Is the item I described in my original post actually the ignitor - if you know (shaped like a large book of matches)?

Another question concerning the timing belt. Would a broken belt cause lack of spark? - the distributor does spin and is hooked up the an electrical circuit.

[labman]

Always make continuity and other resistance measurements with the power off. If the belt is broken, the distributor will not spin. It is possible something went wrong with the distributor shorting out the coil and ruining it. Can't help with the igniter. I am afraid it is some slang term not normally used.

[chubaka]

Always make continuity and other resistance measurements with the power off. If the belt is broken, the distributor will not spin. It is possible something went wrong with the distributor shorting out the coil and ruining it. Can't help with the igniter. I am afraid it is some slang term not normally used.

Thanks again. When my son caused a spark while probing inside the distributor could that have shorted out the coil? The obvious problem was what seemed to be a slight melt down and separation at the base of the rotor, I doubt that could have shorted the coil. Perhaps it is the other way around and the shorted coil fried the base of the rotor - the way I figure it the damage to the rotor would only mess up the timing as it was spinning out of alignment, and not kill the rotor. Not that it takes away from the solution you have pointed out (replace the coil), and although it is possible, I have a hard time believing that it was a mere coinsidence that the coil went the same time the rotor went. It would satisfy my curiosity if I knew if the coil damage was done with a missplaced screwdriver or the coil problem affected the rotor. I may sound overly concerned but I like to understand how things take place, in this incident how is it both the rotor and the coil went bad at the same time? Can you comment? If you cannot it is not at all important -what is important is that the problem has been discovered and tomorrow we will replace the coil. I post the results after the fix - that is if we can get around with the snow we just had fall on our area..
I learned of the term "ignitor" when I started my search about not having a spark. The author, in the FAQ section of his web site, mentioned that if the main relay was good then one would have to check the coil and if the coil was good then the "no spark problem" had to be caused by a faulty ignitor (one would need a "scope" to check this "ignitor"). He didn't describe the way the ignitor looked so that is why I asked here - I had no idea what this ignitor looked like either..

[thebriggsdude]

You know, might be on to something with the coil or ignitor, I've seen coils melt down before. Not sure if the ignitor would screw up but might

[CroCivic91]

There actually is such a thing called an Igniter in Hondas. Full name is Igniter Unit. It is located under the Ignition Coil (the thing on top, with 2 wires attached to it, and some circular opening on side), behind the plastic Leak Cover that "guards" the rotor. It has 3 or 4 male pins going out of it, and does look like a match box.

What you should do first is check the 50A fuse, numbered 32 in the fuse box under the dash. If it is blown, replace it first, and see if things work.

In order to reach the Igniter Unit, you should remove the distributor cap, rotor and leak cover. Now you should see 4 wires connected to the igniter: WHT, BLK/YEL, WHT/BLU and BLU.

Now here is how to diagnose problems:
Check for voltage between the BLK/YEL wire and the body ground with the ignition switch on. There should be battery voltage. If there is no voltate, check for an open in the BLK/YEL wire between the igniter unit and the ignition switch.
Next, check for voltage between the WHT/BLU wire and the body ground with the ignition switch on. There should be battery voltage. If there is no voltage, check for: faulty ignition coil or an open in the WHT/BLU wire between the igniter unit and the ignition coil.
Next, check for continuity between the WHT wire and the body ground. There should be continuity. If there is no continuity, check for: and open in the WHT wire between the igniter unit and the ECU or poor ground.
Next, check for continuity between the BLU wire and the body ground. There should be continuity. If there is no continuity, check for: and open in the BLU wire between the igniter unit and the tachometer (or the A/T control unit) or poor ground.
And if all continuity and voltage tests are normal (with a known good 50A fuse), but the engine won't start - replace the igniter unit.

While I'm writing this, here is how to check for a bad ignition coil.
There is a BLK/YEL and WHT/BLU wires connected to the coil. Call the terminal to which the BLK/YEL is connected terminal A and the other one terminal B. The circular thing on the side of a coil is a secondary winding terminal. Switch ignition to OFF. Remove the screws and disconnect the wires from terminals A and B. Using an ohmmeter, measure resistance between the terminals. Replace the coild if the resistance is not within these specifications: between the A and B terminals - 0.63-0.77 ohms, and between terminal A and secondary winding terminal - 9,760-14,640 ohms.

Hope this helps at all.

[chubaka]

Once again - my deepest appreciation for all your help.

Crocivic91 - WOW! You must be a professional if not you should be. Those are some very specific directions and I thank you so much for them. With the knowledge you have given me I feel very confident about troubleshooting this problem - My hat goes off to you! Better yet, to use the hockey term - you have scored a "Hat Trick". I'll get back and post the results a.s.a.p.

[CroCivic91]

:) :) :)

Thanks man, I'm not really even close to being a professional, I just know how to use my Repair Manual, and have had an opportunity to see those things with my own eyes :)

Do get back to us when you solve the problem :)

[labman]

Thanks Crocivic. There are many non professionals on the net giving good answers to help others. Crocivic has specific experience with Hondas and electronic distributors, which I lack. I only had one car that had an electronic distributor. I can do points and direct fire systems, but struggle with electronic distributors.

[thebriggsdude]

Same here, I'm use to point type distributors etc. show me a honda and I can do engine work but electronics that are past 1988 mostly not

[chubaka]

CroCivic,
Here's one that totally stumped not only me but the parts guy at the Auto Zone parts store.
I started those tests you posted with the easiest test first - the coil. After checking the resistance between A & B which are marked + and - on the coil (the coil was not connected), I measured zero ohms. This convinced me that the coil was bad. (It should have read .63 -.77 ohms as you mentioned). After checking the junk yards and finding no coils, by the way 1990 - 1991 Civic's, CRX's and Integra's all use the same coil, we left empty handed. This left no choice but to buy a new one. I went to The Auto Zone - they were the least expensive - and took the original coil and my volt/ohm meter with me. At the store I ran the same test on the new coil. When it proved to be the same as my original coil I told the employee that this brand new coil was bad. He pulled out a book and his meter to verify my results. His book, although having slightly different specs (.5 - .9 ohms resistance for the primary coil tested between A & B or + & -) didn't change things as there was no resitance where there should have been some. I had him call another store where he had the manager take one of his brand new coils, run the same test and come up with the same results. Two brand new coils both reading no resistance in the primary is really hard to believe but there it was right in front of our faces. He had no explanation for this. What do you think is going on here? How should I handle this?
By the way never tell people you have the manual. Keep them thinking we have a genious on this forum... LOL

[thebriggsdude]

Hey have to say, same way with any coil, be it car, mower or anything that uses a coil, even if they are new they might still be bad. Had a guy go through 5 tecumseh coils till he got a good one. I know its stupid but they are mass manufactured and they rarely test but a few.

[CroCivic91]

The thing that might be a problem is if you set the scale on an ohmmeter to a too big value. For instance, the smallest scale I can set on my multimeter is 200ohms and the biggest scale is 20 megaohms. Now I did a little test. Took a piece of wire and measured resistance with the smallest scale - 200 ohms, and got a result of 0.4 ohms. When I set the scale to 2000ohms - I got a result of 0.

Perhaps your ohmmeter cannot measure fine enough? If it cannot measure such fine values, try the other test (you should get about 10 thousand ohms - it should be able to measure that). Also, do try and troubleshoot all other tests, and perhaps go to a store that sells ohmmeters and bring your coil with you, and say you'd like to test how fine their ohmmeters are :)

Did you check the fuse? How did other tests go?

[chubaka]

CroCivic91,
I have to check with my son to be sure if he checked the fuse. We only tested the coil first because that was the simplest test to do. When it seemed that the coil was no good the next planned step was to replace it and if there was no start we would go on to the other tests.
I am a little confused about the instructions for the other tests. Beside not knowing where the ECU (Electronic Control Unit) was and also not knowing where the A/T control unit was and assuming that "poor ground" meant anyplace on the car other than the negative battery terminal - I am not at all understanding the last sentence in that paragraph " And if all continuity and voltage tests are normal (with a known good 50A fuse), but the engine won't start - replace the ignitor unit". That seems to be saying if the ignitor unit tests good and the engine won't start there is something wrong with the ignitor unit. If we changed the ignitor unit with a new one it should also test normal shouldn't it?
As far as the calibration/scale of my ohm meter goes, it is a relatively simple meter that has only one scale. Please see the posted picture below - the ohm scale is the top one in green and should easily show the measurement described in the specs. By pointing between zero on the left and one. This meter was calibrated for zero by means of an adjustment wheel while the test leads were touching each other.



If you can clear up the test procedure questions I will run the tests on the ignitor unit unless of course we somehow get the engine going before. I spoke to the District Manager of Auto Zone who advised me to contact the manufacturer of the new coil (Not Original Equipment marked Japan but made by Wells Manufacturing) also he suggested that we buy one and try it and if it doesn't work bring it back.
I'll post further progress, even if we have to burn the car - lol

[chubaka]

Regarding the fuse. My son looked under the dash and found only one fuse box on the drivers side - there were no 50A fuses in this box. He did find a 50A fuse under the hood marked IG - I think this is the fuse referred to and it is good. Do you think this is the right fuse? If not could it be really hidden somewhere else under the hood?

[CroCivic91]

First, the confusing paragraph. It makes perfect sense to me, because all the tests are only showing that all the wires and everything AROUND the igniter unit works correctly. If everything works correctly (meaning that all tests show voltage and continuity, and coil is fine), and the engine still doesn't run, then the problem is in the igniter unit itself, because you just tested that all the voltage and continuity that should reach the unit is reaching it -> the unit itself is not working properly.

There is only one fuse box under the steering wheel. If it doesn't contain the 50A fuse, then the only other place is the fuse box under the hood. It does contain all the "heavy" fuses. IG would make me think it is IGNITION, but do look on the cover of the fuse box - there should be a drawing of what is under the cover, and it should say on top what is what.

A/T control unit shouldn't worry you, unless you have an automatic transmission. I, personally, have never even driven in a car with automatic transmission, so I cannot help you if you do have automatic transmission.

ECU is located under the carpet, where passenger's feet rest when sitting, just sort of below the glove box, but a bit closer to the firewall.

One good thing about the ECU is that you can see what error codes it throws - it could point you in a good direction when there's something wrong with the car. To check the error codes, pull the carpet a bit towards the seat, and you'll see a circle in the middle of a metallic box. It is a LED that will blink once you turn the ignition to position II (when lights turn on in the gauge cluster, but you don't yet crank the car). Count blinks after that. There may be a few codes. Write them all down and post them here. For example, if you had problems with your injection system - you would get 16 blinks from ECU - code 16.

Now back to the topic - From the ECU a wire harness is going through the firewall and around the engine bay. Instruction in the test says to check for an open in the WHT wire going from igniter to the ECU. So just follow that wire all the way to the ECU and see if it's OK.

I do agree that your scale is fine enough, and it would easily measure 0.6 ohms. I've also never worked with an analog ohmmeter, and cannot really help you with that :( One interesting thing to notice (keep in mind I have no idea how to calibrate an analog ohmmeter): when I connect the two probes on my multimeter, I get a reading of 0.4ohms. Could it be that when you calibrate it - you set 0 to in fact some value slightly higher then zero, and when trying to measure such small resistance - you get no reading?

[chubaka]

CroCivic91,
After I posted the fact that I was confused about some of the instruction, I realized as I was performing the tests - two wires hot, two wires continuity, that the test was being performed with each wire disconnected from the Ignitor Module. I only realized this when I actually had hands on. I couldn't get back to post it until now - thanks for the explanation. I was actually not testing the module only the circuitry.
I also didn't understand, although I had a suspicion, that this test involved the coil. When I spoke to the district manager of Auto Zone he suggested two things. I should call the manufacturer of the after market coil to ask them why the primary had no continuity (I did and they were closed until Monday) and he encouraged me to try the new coil and if it didn't work I could bring it back for a full refund. I went back to the store and purchased the new coil and a new ignitor module. Now if I was able to comprehend that the ignitor module test, that proved normal by the way, also pronounced the coil being good - I would't have brought a new coil. Lately my brain is getting in the way of my comprehension. As it turns out I have to bring back the new coil because the engine now starts as a result of changing the ignitor module - the original coil is good. I wonder if the large spark my son caused while probing around in the distributor caused the Ignitor to blow - not that it really matters because the car is fixed thanks to this forum, those who posted help and especially to you for posting the needed information from the manual and your continued help in shedding light on all my questions. Many thanks for your consideration and time spent with the manual and your keyboard. I am truly grateful!