New fuses have corrected the meter issue.

When I touch the leads together while on the Ohm scale, I am now reading zero.

I switched the ignition key to the "run" position, disconnected the two wires from the dead-man (tether) switch at the rear of the bike (making sure the ends aren't touching), put one lead to the kill switch pin of the CDI connector and the other to ground. The meter did not change. It still reads OL.

I reconnected the CDI and tested for spark. Nothing.

I am not sure where to go next. It appears as though the switches are not shorted to ground. I reconnected the dead-man switch and re-tested with no change in readings.

Thanks,
Chevytech

 

Some basic resistance checks:

Unplug the CDI. Measure the resistance of the AC ignition power pin on the CDI wiring harness connector to the ground pin of the same connector. You should see about 400-500 ohms (0.4K to 0.5K Ohms).

Measure the resistance of the Timing Trigger pin to the ground pin. You should see about 150 ohms (0.15K Ohms).

Measure the resistance of the Ignition Coil pin to the ground pin. You should see about 0.5 ohms. Note that 0.5 ohms is 0.0005K ohms, so anyone reading this who doesn't have a meter that auto ranges will have to turn down the resistance scale to the lowest setting possible.

Unplug the spark plug. Measure the resistance of the spark plug wire to ground. The connection should not be open, but it may be a very high resistance like 10,000 ohms (10K Ohms). It may also be a much lower resistance. At this point we're just making sure that there is a path through the coil to the spark plug.

Report back values for each of the above. There may be valuable clues in the measured values, or we may have to go to the next step - which is measuring voltages while cranking the engine.

 

Lynn,
I took the liberty to remove some of your message, then replied within your message.

I "read ahead", if you will. I've been reading past troubleshooting you have been part of. If we do move into testing for voltage while cranking, will I have my meter on AC or DC voltage, or does it depend on where we are within the system? I realize this is a 12V DC system, but I read in one of your posts where the CDI is actually AC.
I know I'm jumping ahead here, but that has me confused.

I didn't expect to have these issues when I purchased the bike, but I must confess that I'm quite intrigued by how these systems work.

Thanks again for helping.
Chevytech

AC ignition power pin to ground pin (~400-500 ohms (.4K to .5K Ohms))
My meter read: .329K Ohms.

Timing Trigger pin to the ground pin. You should see about 150 ohms (0.15K Ohms).
My meter read: 119.6 Ohms.

Ignition Coil pin to the ground pin. You should see about 0.5 ohms.
My meter read: .6 Ohms.

Spark plug wire to ground. The connection should not be open, but it may be a very high resistance like 10,000 ohms (10K Ohms).
My meter read: 4.2K Ohms.

Lynn- thanks for taking your time to help me with this. I would sure like to buy you lunch if you ever find yourself south of Houston Texas!

 

All of those resistance readings sound OK. Its time to measure voltages.

Yes, your quad has a 12 volt DC system for cranking the starter motor and running the lights. Electric start small engines are a fairly recent add on feature to older pull and kick start systems. The ignition systems on those (and most new) quads are powered off AC voltage generated from the the stator when the engine is turned. It is kind of like your lawn mower. You pull the cord and it starts up. No battery, and no starter motor anywhere to be found. No 12 volt anything...

Lights in the past have been AC powered too, and some still are, but DC powered lights are more common on quads these days.

Back to the subject at hand:

Unplug the CDI, and set your meter to measure AC voltage on the 100 or 200 volt scale. For all of the following tests make sure the kill switches are set to the run position (handle bar and rear tether) .

1) Measure the voltage from the AC ignition power pin to ground while cranking the engine. You should see 40-80 volts AC. What do you measure?

2) Set your meter to the lowest scale possible. Ideally this would be something like 2 volts AC, but many meters don't go this low. What is the lowest scale voltage you have on your meter? Crank the engine. What voltage do you measure? You should see 0.2 to 0.4 volts AC. This depends a lot on your meter. This test isn't foolproof because it is possible your meter doen't respond to this bizarre looking waveform like most other meters. If you have access to multiple meters then take advantage and report all the readings from all the different meters.

3) Set your meter back to 100 or 200 volts AC. Plug the CDI back in. Measure the Ignition coil output pin from the CDI. Probe through the insulation on the wiring harness if you can't get at the connector pin itself. Crank the starter while monitoring the Ignition Coil output pin for 5 to 10 seconds. You should see mostly zero voltage with random numbers in between. Once again this test is using meters to look at things they weren't designed to do. An oscilloscope is what we need, but a meter is all most people have. If you have more than one brand meter take advantage. What we are looking for is those random numbers. These are where the meter just happens to catch a moderately high voltage spike happening where the plug is getting fired. This is a low duty cycle event (the spike is only a few 10 millionth's of a second), hence the mostly zero voltage output with occasional random spikes.

 

1) Measure the voltage from the AC ignition power pin to ground while cranking the engine. You should see 40-80 volts AC. What do you measure?
My meter read: 53V

2) Set your meter to the lowest scale possible. Ideally this would be something like 2 volts AC, but many meters don't go this low. What is the lowest scale voltage you have on your meter? Crank the engine. What voltage do you measure? You should see 0.2 to 0.4 volts AC. This depends a lot on your meter. This test isn't foolproof because it is possible your meter doen't respond to this bizarre looking waveform like most other meters. If you have access to multiple meters then take advantage and report all the readings from all the different meters.
My meter read: .525V
Note: I didn't see where you wanted this tested, but it makes sense to me that you would want to see this reading at the Timing Trigger connection since we just tested at the ignition coil. Please advise if I did this wrong.
My meter can go out to three decimal points. I don't have access to any other meters until Monday. If you deem it necessary, I will get my hands on some friends meters and bring them home to repeat this test.

3) Set your meter back to 100 or 200 volts AC. Plug the CDI back in. Measure the Ignition coil output pin from the CDI. Probe through the insulation on the wiring harness if you can't get at the connector pin itself. Crank the starter while monitoring the Ignition Coil output pin for 5 to 10 seconds. You should see mostly zero voltage with random numbers in between. Once again this test is using meters to look at things they weren't designed to do. An oscilloscope is what we need, but a meter is all most people have. If you have more than one brand meter take advantage. What we are looking for is those random numbers. These are where the meter just happens to catch a moderately high voltage spike happening where the plug is getting fired. This is a low duty cycle event (the spike is only a few 10 millionth's of a second), hence the mostly zero voltage output with occasional random spikes.
I could not get any reading during this test. I tried multiple different ranges and tried the "Auto Ranging" function of the meter. I couldn't get anything.

Thanks again. I look forward to hearing from you.
Chevytech

 

1) 53 volts AC is fine.

2) Yikes. I didn't say what pin to measure. Sorry about that. Yes, I meant the trigger voltage, and what you got looks fine.

3) There's no such thing as "I didn't get anything". The meter is displaying something. Did you get nothing but zero volts? That is important info. If you're getting only zero volts that says your CDI isn't getting triggered, or the CDI is not able to get charged up by the AC ignition power line. Either way the CDI is not working. It looks very likely your CDI is bad. There is a remote possibility that the coil inductance is low, but I would expect that this would cause low voltage spikes on the ignition coil output and not zero volts.

If it were me I would double check all the tests so far, then if nothing has changed I would order up a new CDI.

 

3) There's no such thing as "I didn't get anything". The meter is displaying something. Did you get nothing but zero volts?
Rookie mistake, sorry. The meter did not move from zero.

That is important info. If you're getting only zero volts that says your CDI isn't getting triggered, or the CDI is not able to get charged up by the AC ignition power line. Either way the CDI is not working. It looks very likely your CDI is bad. There is a remote possibility that the coil inductance is low, but I would expect that this would cause low voltage spikes on the ignition coil output and not zero volts.

If it were me I would double check all the tests so far, then if nothing has changed I would order up a new CDI.
I will definetely double-check my readings.

I'm assuming there's some type of Hall-effect switch that triggers the CDI? Do these switches fail? Should we test it also?

If the results are conclusive, where would you recommend I purchase the CDI?

I noticed there are several "performance" CDIs available. While I'm not interested in hot-rodding my son's 4-wheeler, I am wondering if they are built better and worth the extra few dollars?

I remember reading in another post of yours that there are AC and DC CDIs. With that said, there seem to be several on e-bay that are very inexpensive, but new. I'm assuming that with the tests we performed, we have an AC version?

Is there a way, other than relying on what an e-bay seller says, to determine which type I am buying? Does the color of the connector on the CDI indicate it's voltage type?

Thanks again and again. You are a great person to help a perfect stranger.
Thanks,
Chevytech

 

My comment embedded in Red:

 

Lynn,
I ordered two CDIs and an ignition coil off ebay after your last post. I figured I should get two CDIs in case (when) the new CDI fails. I also ordered the ignition coil for S&G, so we would have it. The parts showed today, so when I got home around 10:00pm from work, I put your diagnosis to the test!

You were absolutely, 100% dead-on the money with your diagnosis of the failed CDI.

I can't thank you enough.

I am working late all week, so I won't have much time to put the bike back together until this weekend. I am SO looking forward to seeing the look on my boys face when I tell him it's for him! As far as he has known, I brought the bike home to fix for a friend's son. It's going to be great!

I hope you will tell me if there's anything I can do to repay you for your help. I have been an auto tech for years and to be honest- I couldn't imagine devoting as much time and knowledge as you have to help someone I don't know without being paid. I was clueless of how to diagnosis this problem, which really helps me to relate to how my customers feel. Not to get too corny, but I am really approaching "helping" people with car troubles in a whole new way!

Thank you very much.
Chevytech

 

I'm glad you got it running .