G1e Resistor overheats when connected, blows fuses

[mark b]

I have a 1981 electric G1 that I believe is wired correctly (at least it follows the wiring diagram I have.) It runs in both forward and reverse, but as soon as the battery cables are connected it sparks, even when the ignition is off, and the resistor coil gets extremely hot. I know this can't be good and so I don't run it. It blows fuses constantly if I do, mainly the reverse fuse, and it then it stays in reverse even if the key is switched off. I'm told this may be a wiring short in the wiring harness, but I can find no bare or frayed spots.

Any ideas? Bad solenoids? Bad ignition?

Other possible symptoms: 1. Reverse buzzer is blown. 2. I had to replace a brass bolt and wire at the highest speed copper contact with another brass bolt and nuts, and it now arcs and sparks whenever the speed control lever touches it.

[mark b]

It doesn't look like any Yamaha gurus are going to reply, so I'll just post my further discoveries in search of a solution for the benefit of anyone who comes after me.

A Yamaha mechanic (who said he'd never worked on an electric G1 in his life) said he suspected a ground short. Advised that I trace the wiring harness. Sure enough, I found a small possible short between the connection coming off a solenoid and a ground wire. I insulated that and repositioned the wires, but when I reconnected power I still have hot power running through the system even when though the ignition is off (or even disconnected entirely). Resistor coil still heats up like a toaster and battery connections still arc when hooked up. Now I suspect a faulty solenoid.

I will keep you posted as to what I find. I have a guide for how to check solenoids. Any input would be appreciated.

[mark b]

I have removed both solenoids and removed their caps (simple screw off lids) and found the following suspicious things.

The Forward solenoid looked like it had actual oxidation on the copper connector discs on the "N. Open" end of the solenoid. To me this indicates that those connectors rarely ever touched in recent months. The "N. Closed" end of the Forward solenoid had fresh, good contact marks on the copper connectors, but one of the two switching wire hairs on this side looked broken off or too short to make contact when the cap was screwed back on. As it turns out, this short trigger hair corresponds to the ground connection where I first located the suspicious short mentioned in my previous post.

The Reverse Solenoid was in much worse shape. While it seemed fairly healthy under the "N. Closed" end cap, under the "N. Open" side the connection arm was burned and the connectors were melted and even partially consumed. Very little metal was left and what was there was warped and bubbled.

I'm guessing this means I need to replace both solenoids. Hey, they're only 33 years old.

[mark b]

Sure enough, no one ever jumped into this thread with any help. I'll post the rest of the story for the benefit of those who come after me.

Fortunately, I fixed my cart myself with the help of my medical doctor brother-in-law who has never golfed or owned a golf cart in his life. But he knows cars and he confirmed that High Amperage solenoids can, in fact, fuse shut in the closed circuit position (power hot), which is what mine had apparently done thanks to the short on the ground wire connected to one of the two solenoids.

Luckily, I was able to buy replacements on ebay for $67 each. (Thank god that these old G1's are no more complex than toasters.) I also replaced the reverse warning buzzer for $15. Once they had arrived, I hooked them both up exactly according to the wiring diagram and found that the system did not heat up nor spark with ignition off when the final battery cable was connected. A good sign.

I turned the key and hit the throttle and off I went -- in reverse with the key switched to forward, and forward (with the buzzer buzzing) when in reverse. No problem however, since these carts have two identical solenoids for forward and reverse. I just switched the trigger leads to the opposite of what the wiring diagram said, and Viola! Forward in forward, reverse with buzzer in reverse. No sparking, no overheating. Key off, power off.

And that is the rest of the story.