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HOW TO: No Crank/No Start Diagnosis

Discussion in 'Technical Articles' started by Hammer, May 21, 2012.

  1. Hammer

    Hammer Moderator
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    We often hear the question "When i hit my start button I just hear a click, what do I do?". Well, my 660 began having this issue on my last ride, so while diagnosing mine, I took some pics and wrote down some meter readings. Hopefully this will help some members in the future. I did this on my '07 660 Grizzly, but the same tests would apply to any vehicle with an electric starter.

    First of all let me clarify a few things.
    "Cranking" would be when the starter engages and turns the engine. An engine that cranks, but doesn't start, indicates a problem with fuel, spark, air or compression.
    A "Cranks but doesn't start" diagnosis would focus on timing, coils, carburetors, etc.

    A "No crank, No start" diagnosis would focus on the battery, the starter, the battery cables, the ignition switch, etc., which is what this article will pertain too.


    A little "basic electrical" information may also help. "Voltage" is the amount of "push" in the circuit. Typical battery voltage is 12.6 volts. Voltage can be present, but if there is a loose connection, amperage will have trouble passing through a circuit. "Amperage" or "current" is a measure of the electrons moving in a circuit. Amps are what do the work. A circuit must be complete in order for amps to flow. "Resistance", measured in "Ohms", opposes the flow of electrons. Dirty or loose connections, corrosion in a cable, broken wire strands, etc. give us electrical resistance. "Loads" or "consumers" are devices in an electrical circuit that are designed to consume voltage. The load side of a relay, the starter, light bulbs, etc. are examples of consumers. An electrical circuit must have at least one consumer, otherwise we have sparks and maybe fire!

    In a starting circuit we have 2 seperate, but interrelated circuits. The first is a low current circuit. This would be the switch, relay and associated wiring. In the low current circuit, the "control" side of the relay is the consumer. This should draw maybe 5 amps total.
    We also have a high current circuit. This would be the battery cables, the "switched" side of the relay and the starter. The starter is the consumer in this circuit. A starter can draw anywhere from 30 to 500 amps depending on what engine it is turning. A single cylinder atv starter will be on the low end of the spectrum.

    A relay, or solenoid depending on the circuit, allows a low current circuit to control a high current circuit. We use the low current through the switch to the "control" side of the relay to energize an electro-magnet, which closes the switch on the "switched" side of the circuit. The switched side of the relay should NOT be a consumer.

    Now that we understand the circuit we are working with, let's do some diagnosing!

    The necessary tools are: a basic set of hand tools, a DVOM, a wiring diagram and a properly charged battery

    [​IMG]
    [​IMG]

    According to our diagram, the "ignition" fuse is the one that powers the switch side of the starting circuit. A little tip here is that if the relay "clicks" when you hit the "start" button, this fuse has to be OK. If this fuse is blown, there could be no "click" since the "clicking" is the sound of the relay closing. No "click" does not indicate that the fuse is definitely bad, however it would be a suspect.
    [​IMG]

    Lets explore what to check if there is no click.
    Power coming from the ignition fuse passes through the CDI. The CDI is making sure that the shifter is in park or neutral, or that the brake is depressed. If these conditions have been met, power goes to the relay on the blue/white wire and then goes to the start switch on the blue/black wire. The switch is on the ground side of the circuit. From there ground is found through a black wire.

    Start testing by ensuring that the machine is in fact in park or neutral, or that the brake is depressed. These can be verified with the indicator lights or the "brake" light on the rear of the machine. Next, check the fuse. If the fuse is blown remember that fuses don't just die, they are the intentional weak link in the circuit. If a fuse is blown, it is the result of too much amperage in the circuit. Look for short circuits, chafed wires, etc.
    If the fuse checks out, go to the relay. Put the black lead from your DVOM on the battery negative post and the red lead on the blue/white wire. There should be battery voltage present (@ 12.6 volts).

    [​IMG]

    If there is no voltage here, the problem is between the fuse and the relay. Check the wires for opens, loose connections, the kill switch, etc. Check for power going into the CDI on the red/blue wire and power coming out on the blue white wire. If power is going in, and all other conditions for starting have been met, the CDI is the culprit. This can be verified by jumping power to the blue/white wire from the battery. If the engine will now "crank" over, the CDI is faulty. If the CDI is faulty, the engine most likely will not start, only crank.


    If power is present at the blue/white wire, move the red lead to the blue/black wire. There should be battery voltage present here if you are NOT pressing the start button.

    [​IMG]

    Remember, the switch is on the ground side, so when the switch is not depressed, there will be source voltage all the way up to the switch. When the switch is pressed there should be very little voltage on the blue/black wire (less than .25 volts). If there is no voltage present at the blue/black wire when not pressing the switch, the relay needs further testing.
    This step is called a "Voltage drop" test. We cannot test resistance of a working circuit, so the next best thing is test the amount of voltage a device, or wire "drops". Since the relay is the only consumer in the circuit, it should consume all of the voltage. Place the red lead on the battery positive post and the black lead on the blue/white wire. While cranking, the meter should read less than .5 volts. Next, place the red lead on the blue/white wire and the black lead on the blue/black wire. The meter should indicate 0 volts while NOT pushing the start switch, and it should read very close to battery voltage when the switch is pressed. A reading of less than battery voltage while pushing the switch indicates that something else is consuming voltage in the circuit.
    Lets say you find only 6 volts across the relay, but you had a good reading on the previous test. This would tell us that something is consuming the other 6 volts and the resistance is further in the circuit, possibly the switch. A high voltage reading on the first voltage drop test would indicate the the unwanted resistance is on the fuse side of the circuit.
    If our tests so far indicate good readings, move to the start switch. There should be 12 volts present on the blue/black wire going into the switch and 0 volts on the black wire coming out of the switch when NOT pushing the switch. When pushing the switch, there should be no more than .25 volt on either wire. Connect the red lead to the blue/black wire and the black lead to the black wire. While cranking there should be less than .25 volts. If there is more voltage there while pressing the switch, we have resistance either in the switch, or in the ground circuit. If checking actual voltage (red lead on the blue/black wire and the black lead on battery negative) and more voltage is present while cranking, check the same way on the black wire. If that voltage is still present the resistance is on the ground wire. If not, the switch is the culprit. If checking voltage drop across the switch and you are getting more than .25 volts the switch is the problem.


    Now let's say that the relay was clicking, we can assume that the low current circuit is OK. This is what my Grizzly was doing.

    Open circuit voltage across the battery terminals (red lead on B+, black lead on B-, key off) should be more than 12 volts. Mine was a little low, but not bad. I had about 12.06 volts. Next, leave the leads in place and attempt to start the machine. Battery voltage should drop 1, maybe 2 volts while the engine is actually cranking. If the engine isn't actually cranking, voltage should not drop at all. If it is dropping below 9.5 volts, the battery is weak and should be charged, or replaced and then retested.

    [​IMG]

    If battery voltage checks out, voltage drop test the short cable from the battery to the relay. (red lead on B+, black lead on the same cable at the relay).

    [​IMG]

    While pressing the start button, the meter should not read more than .25 volts. Higher readings indicate a problem with the cable. Next move the red lead to the relay where the black lead just was. Put the black lead on the other post.

    [​IMG]

    While pressing the start button, the meter should read less than .5 volts. More indicates a problem in the relay. This is where my problem was. The cable leading out of the relay, going to the starter was loose. Simply tightening the bolt solved my issue. But we'll keep going to show the rest of the tests.
    If the relay checked out, place the red lead on the "out" side of the relay (the cable from the relay to the starter) and the black lead on the starter cable post.

    [​IMG]

    The meter should read less than .5 volts while pressing the start button. More indicates a problem in the cable. If the cable checks out, place the red lead on the starter cable post and the black lead on the starter case. While pushing the start button, the meter should read whatever battery voltage was while pushing the start button. The starter is the only consumer in this circuit, so it should be consuming all of the voltage. If it is not, and everything else has checked out, the problem has to be the ground wire. This can be checked by connecting the red lead to the starter case and the black lead to battery negative. Again, voltage drop should be less than .5 volts while pushing the start button.

    By this point you have checked all of both the low and high current circuits and should have located your problem somewhere in the testing. Good luck with your diagnosis and I hope this helped!
     
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  2. RTxmr800

    RTxmr800 Member

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    Good info there hammer ol' pal !!!! I am sure that will help a lot of people out !!!!


    Side Note

    I am happy to see that I am not the only one that does maintenance in my flip flops!!!
     
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  3. Butch450

    Butch450 Administrator
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    Thanks for the write up Jack. Sure it will help a lot of folks in the future. :cool:
     
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  4. Hammer

    Hammer Moderator
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    yep, flip flops, a tank top and a cold one makes the "diagnostisizing" go a whole lot better!
     
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