yamaha g1 keeps blowing the negative fuse

[bvilleharleycart]

Ok so we got the broken axle fixed on the g1. Many thanks to smikindawg for helping out on this problem. Then I go for a test drive get to the end of our driveway and put it in reverse and it has no power . Check the fuses and the negative fuse is blown. Replaced it and it still keeps blowing. Any help advice or similar experiences would be helpfull. We've been tracing the wires and looking for a short but still haven't found one.

[Prowlerguy1]

Start by trying to figure out what, if any, action is causing the fuse to blow.

Is it when you connect the battery?
Or, when you turn the key to FWD?
Or, when you turn the key to REV?
Or, when the key is in FWD and the pedal is pressed?
Or, when the key is in REV and the pedal is pressed?

If you can figure any of these out, it will help narrow the search.

Let us know.
Todd

[bvilleharleycart]

ok thanks I will try those out and report back. It does seem to have something to do with reverse., plus i've blown all my fuses : (

[bvilleharleycart]

sorry it took so long to get back. Put a new fuse in and it ran great for a day then went to take garbage down today and it blew the fuse again. It is blowing as soon as you put it in reverse, I dont even get a chance to push the pedal. What do ya think. I keep searching wires and cant find any bare spots????

[Prowlerguy1]

With a normal system and the KEY OFF, the circuit should have the following voltages (Red is +Vbatt [+12V dc] and Grey is -Vbatt [0 V dc]) in the attached drawing named [yamaha-G1-wiring-diagram_Normal Condit_KEY OFF].

When you turn the key to REV and step on the pedal, the light blue wire gets 12Vdc applied which energizes the solenoid and closes the REV Relay. This essentially makes the N.O. contacts of the REV relay now at -Vbatt (0V dc) because of the voltage drop across the starter/generator. This is depicted in the attached drawing named: [yamaha-G1-wiring-diagram_REV KEY ON_NORM].

HOWEVER, all of this would only happen with the key in REV and THE PEDAL DEPRESSED!

You say that it's happening before you even press on the pedal. So, that makes this a little more interesting. So, if that is the case, and this is happening without the pedal being pushed then we have to determine where the +12 Volts is coming from and how it is getting to the Neg fuse.

To do that we have to look at the KEY SWITCH diagram (at the top of either attached drawings). According to the KEY MAIN SWITCH diagram, when you put the key into REV, the following wires are tied together (read across the bottom row in the chart):

1. W, R/W & L (This takes power from the pedal switch and applies it to the S/G excitation field, the V/R and the REV relay solenoid). I would not spend a lot of time looking at these wires, since they are all controlled by the pedal.

2. W/G, B, R,P (This takes power straight to from the fuse link and applies it to the CDI magneto, the back-up buzzer, and according to the diagram....believe it or not....directly to the Black wire which is GROUND! There must be a typo in this diagram.

Using common sense here, I suspect that the red wire from the fuse link gets applied to the P wire (back-up buzzer), the W/R wire (CDI Magneto and Ignition wire) and does not apply it to the Black wire.

Now, since the PEDAL SWITCH (STOP SWITCH in the drawing) is not causing this problem, we should be able to take any colored wires from the pedal switches out of the consideration as the culprit.....since the problem is caused before the pedal is depressed.

The pedal switch wires colors are: W, R, B/W and B. In fact, the White (W) wire is the wire that brings the controlled, pedal switch power to the main switch. So, that can be disregarded. Since the White wire power goes to the R/W (Red with White stripe) and L (Light Blue) wires, I would disregard these wires as well. There is no way that the problem will be associated with the Y (Yellow) wire since this activates the FWD solenoid and that you report works correctly.

Next, we can take away consideration of the B/W wire, since that is always connected to one end of the Neg fuse (it's essentially a ground wire whenever the pedal is NOT pushed).

That only leaves 3 wires that could be the culprit: the P (purple) wire to the backup buzzer, the W/R (White with a Red stripe) wire to the CDI magneto and ignition module, and the W/G (White with a Green stripe) wire that also goes to the CDI magneto and Ignition Module.

If your backup buzzer works, you can rule that out.

So, the only thing left to look at is the REV direction of the CDI Magneto or Ignition Module.

My best guess is that this is either a problem with the KEY SWITCH itself that is putting power onto a wire that it should not be. Or, it is a problem with something in the CDI system. Either the magneto or the CDI Unit. I am not very familiar with these magneto systems, so hopefully someone else can comment on this.

I would troubleshoot this by taking the plugs off of the MAIN KEY SWITCH. Then, use a jumper from the RED wire (remember this has +12V all the time)and then one at a time put the power (jumper) from the RED wire to:
A. the Purple wire (should make the backup buzzer BUZZ);
B. the W/R wire and;
C. the W/G wire and see which one blows the fuse.

BTW, I recommend testing the W/G and W/R wires both, because there is another typo in the main switch diagram and there are two W/G columns. I cannot tell from this wiring diagram which one of these is for the FWD direction and which one is for the REV direction (or which to believe). Apparently, it makes a difference. Again, someone with more magneto knowledge might be able to help with this.

Based on this, you'll be able to tell which component is the problem.

If none of these blows the fuse, then it is likely the switch itself that is causing the trouble and connecting the fuse link power to ground when it's not supposed to.

Report back what you find out.
Good luck.

Regards,
Todd

[bvilleharleycart]

Ok that gives me something to start with. I have taken the key switch apart today and all looked good. Give me a while to figure all this out and i'll report back. I am now out of fuses again : ( Thanks for taking the time to look at this and reply with some good information.

[Prowlerguy1]

bville,

Did you get your cart running?

Just wondering what it was.

Thanks,
Todd

[bvilleharleycart]

yes I did, I guess I was a little embarrased to say. I went to the auto supply and bought bigger fuses and it's been fine ever since. I didnt realize they had to be so large and that the ones I got at Walmart were very small (amp) . Thanks for the help though, I know you put a lot into your reply.

[Prowlerguy1]

Awesome! Glad you got running.

No worries, I'm glad that I got to learn more about those carts. May help someone else in the future.

Take care,
Todd

[bvilleharleycart]

Thanks man, i'll post faster next time. I really enjoy our yamaha too. Thanks again Mike