G1 ignition troubleshooting

[SLYS FARM]

following this procedure, I have a few questions
G1 Ignition Troubleshooting

-Remove the positive lead from the battery.
-Remove all harness wires from the CDI.

-Using the ohm meter, VERIFY that the BLACK WIRE IN HARNESS IS GROUNDED.
HOW ???? Attach the positive probe of the multimeter to the harness black wire disconnected from the CDI ? where would I put the negative probe? I'm guessing to a grounded bolt or screw on the engine? With the multimeter set on ohms, should there be no reading at all?? and if numbers do jump around on the meter .. what next? I feel like Im doing something wrong. Once I verify I have good ground I understand the rest of the CDI test procedure. It's always the easy things that confuse me the most. I just need step-by-step details on how to verify a good harness ground.

[AGELE55]

G1’s are tricky little beasts…. The negative battery cable doesn’t get grounded to the frame like every other vehicle on the face of the planet.

But, as to your question. With the battery disconnected and your meter set to OHMS, put one meter lead on the black wire you disconnected from the CDI. The other lead gets touched to the frame. You may need to scratch some paint to ensure a good contact point for you meter lead. For this test, it doesn’t matter which lead goes where.
The CDI black wire is grounded to the frame along with other stuff. The only ground point is just behind the battery, down low by the fender well. It should have a black wire going to it with a fuse in line. It’s pretty common to have a corroded ground wire which can cause some pretty weird issues.
If you let me know the issue you’re chasing, maybe I can help out.
Oh…and you should see the meter read around 1 ohm. The higher the number, the worse it is. If you don’t read anything on the meter, consider that an infinitely high number saying the the wire is open. Most likely bad at the frame ground point mentioned earlier.

[SLYS FARM]

Thank you so much!! Now I have a better understanding of where to go from here. Everything started with an intermittent no crank, no spark, no start. I thought I had it all figured out. As you can tell by my many threads I covered a lot of information. The latest issue was with the carb flooding. Thanks to the suggestions I received on this forum I corrected that problem. I installed the original carb and went to fire her up. I'm back to square one with no spark!! If you look back through my threads troubleshooting the no-spark issue was one of my first challenges. Corroded connections at the stop switch appeared to have solved the no spark, no crank. In any case,.. process of elimination led me to feel it could be a bad coil. I removed the coil, sat down with my multimeter, bench tested and compared it with known good coils, and concluded the coil was working. It did have a fair amount of rust and also an iffy connection so I cleaned it up and put it back on the cart. I turn on the key, press the accelerator and NO POWER !!! I traced back everything I have already done looking for maybe a loose connection. After the stop-switch repair, days ago the cart cranked every time the pedal was depressed, now all of a sudden I'm back to no power! I was attempting to follow instructions for checking the CDI when I became confused about how to check the main harness ground. I'm a newbie when it comes to understanding current, ohms, and using a multimeter. I have had many Ah-Ha moments this week but this is the biggie. I feel I am missing something simple and a bad ground makes sense. It seems to fit in with all the past intermittent problems. Could it be the CDI?? Possibly but I'm not convinced. The wiring on this cart is tightly wrapped with electrical tape and in good shape. A bad ground makes sense. Understanding how to use the multimeter to trace grounds is the ah-Ha moment I need most.

[AGELE55]

It may help to think of the start process as three separate circuits. Bite size chunks if you will.. The first circuit simply gets the motor spinning over using the Starter/ Generator (S/G). So if it’s not spinning, then having a spark won’t do much good .

Circuit 1- Here’s a simplified drawing of the “spin” circuit. To spin the S/G, all you need is to get 12V to one of the solenoids (FWD or REV). Look at your two solenoids. One has a small yellow wire which is the Forward (FWD) solenoid. The other solenoid has a small blue wire which is the Reverse (REV) solenoid. 12v comes in on the small Yellow wire ..OR.. the 12V comes in on the small blue wire. The ignition switch position routes the 12v to the solenoid of your choice. Both solenoids share a common small black wire which should be grounded to the frame. The ground point is behind the battery, down low. It has a fuse in line. Make sure the ground point isn’t corroded, which frequently happens.

Circuit 2- Now, when the 12v makes it down to the appropriate solenoid, there should be power sitting there on the big fat wire waiting to get through once the solenoid clicks. If the solenoid doesn’t energize, then no joy spins the S/G.

I’ll toss in a super simplified flow chart showing what all the fat wires do for a living. If you look through each step starting at the + battery post, you’ll notice the only thing that changes is the position of ONE of the two solenoids. The selected solenoid’s Normally Open (NO) contacts close, due to the yellow or blue wire activating it. The voltage passes through the other (unused ) solenoid in its Normally Closed (NC) position but that solenoid does not energize.

Circuit 3- The “Spark” circuit. Once everything is spinning around like it should, you’ll need a pulsing 12v at the coil to drive a spark at the plug. This is a function of the magneto and the CDI. Lol…haven’t gotten around to sketching that one out yet. But if it comes to that, I’ll certainly do it.

Good luck with the old gal.

[SLYS FARM]

Great charts ! Thank you!! I have a pretty good understanding of how the system works. I fixed the no-power issue and I'm guessing it was bad ground. The bolt holding the wire was so rusted it snapped in 1/2. I drilled out a new hole in the fender and reattached the ground wire. I now have crank but still no spark! I managed an intermittent spark moving the plug wire around so I guessed it may be a loose connection within the boot. Long story short, I tried 2 other coils, one old, one newer, and fixed the boot wire in the original. I checked all connections. No spark, I swapped out the CDI with another CDI from my other G1 ( I have 2 other G1's) still no spark. Now... I have not used the multimeter to check out these CdI's but I doubt they are bad. There is no way all 3 coils are bad. I understand it could be the stator but I'm not convinced yet. How can I check the 2 wires going to the coil? I guess I should check for voltage. I had this cart firing up and running a week ago. After fixing connections at the stop switch she fired up every time. I had a flooding carb issue which obviously affected the spark so I changed out the carb, put in a new spark plug, and other than a quick intermittent spark while jiggling the boot wire .. Im dead in the water. What next???? Where do i go from here?

[mikeasis]

Originally Posted by AGELE55

It may help to think of the start process as three separate circuits. Bite size chunks if you will.. The first circuit simply gets the motor spinning over using the Starter/ Generator (S/G). So if it’s not spinning, then having a spark won’t do much good .

Circuit 1- Here’s a simplified drawing of the “spin” circuit. To spin the S/G, all you need is to get 12V to one of the solenoids (FWD or REV). Look at your two solenoids. One has a small yellow wire which is the Forward (FWD) solenoid. The other solenoid has a small blue wire which is the Reverse (REV) solenoid. 12v comes in on the small Yellow wire ..OR.. the 12V comes in on the small blue wire. The ignition switch position routes the 12v to the solenoid of your choice. Both solenoids share a common small black wire which should be grounded to the frame. The ground point is behind the battery, down low. It has a fuse in line. Make sure the ground point isn’t corroded, which frequently happens.

Circuit 2- Now, when the 12v makes it down to the appropriate solenoid, there should be power sitting there on the big fat wire waiting to get through once the solenoid clicks. If the solenoid doesn’t energize, then no joy spins the S/G.

I’ll toss in a super simplified flow chart showing what all the fat wires do for a living. If you look through each step starting at the + battery post, you’ll notice the only thing that changes is the position of ONE of the two solenoids. The selected solenoid’s Normally Open (NO) contacts close, due to the yellow or blue wire activating it. The voltage passes through the other (unused ) solenoid in its Normally Closed (NC) position but that solenoid does not energize.

Circuit 3- The “Spark” circuit. Once everything is spinning around like it should, you’ll need a pulsing 12v at the coil to drive a spark at the plug. This is a function of the magneto and the CDI. Lol…haven’t gotten around to sketching that one out yet. But if it comes to that, I’ll certainly do it.

Good luck with the old gal.

your diagrams are awesome. I highly anticipate your Spark circuit and how it would flow forward and reverse