New Jinma JM304 Electrical Problems

   / New Jinma JM304 Electrical Problems #1  

Rich Waugh

Platinum Member
Joined
Nov 19, 2008
Messages
803
Location
US Virgin Islands
Tractor
Jinma JM304
Well, I got the crate tractor delivered and assembled, without too much trouble, actually. Oh, the delivery was a bit of a nuisance since the rains had made things so muddy that the truck couldn't get into the right place to offload the crates, so I had to have it dropped in a secondary location. I managed.

The assembly went pretty well, given that there are no real assembly directions, but by watching this forum I managed to get enough guidance to get me through it, though the electrics were a challenge since some of the connectors weren't labeled and required some guesswork and experimentation to get right. I finally got it so that the switches switch the right things and the lights and such work, gauges work, etc. However, I do have one issue that baffles me:

When I first got it ready to start up, it wouldn't crank. Okay, check the battery - sure enough, no good. Replaced that (dealer will reimburse, no problem), still no crank. After much annoyance and checking everything I could think of, I finally traced the wiring for the clutch switch that I though t was causing the issue. Sure enough, it was the switch, but only because it had shifted in shipping and wasn't being actuated by the clutch. Took me all **** day to discover that. Jeezus, what a dummy I can be sometimes! Put it in the right spot and the tractor cranks right up and starts almost instantly. Cool, except for the kicker - starting it up causes the fuse for the regulator to blow and then there are no gauges, no headlights, no indicators. The taillights and turn signals still function, but nothing else. Further, the ammeter then shows a radical discharge - needle pegged to the left. Likewise all the gauges. This one has me baffled.

****, most automotive electrics baffle me (witness the stupidity with that clutch switch), apparently you have to enter into a contract with the Devil himself to be able to make sense of American auto electrics and the Chinese "use whatever color wire is at hand" electrics are worse. Of course, the wiring diagram in the owner's manual is both out of date and, in some cases, in violation of the laws of physics.

Anyone got any clue as to why this stuff is happening? I really want to get this thing broken in and ready to work, but I don't have the nerve to run it in with no working gauges.
 
   / New Jinma JM304 Electrical Problems #3  
Check the wire between the ignition switch and the clutch pedal interlock, and the wire between the interlock and the starter solenoid. You may have pinched one of them during assembly.

One way to test that theory, is to disconnect the one between the interlock wire at the solenoid end. Make sure the transmission is in neutral and the brake is set. Then start the tractor with a screwdriver down at the starter. If the symptoms persist, we'll look elsewhere for your short.

The pegged needle on the ammeter - does that happen only while cranking the starter? or just stay there all the time?

//greg//
 
   / New Jinma JM304 Electrical Problems #4  
I did the crate thing also, 'bout 5 yrs ago. I've a JM354 and I'm still on the original chinese batteries. My one thing that I change that I feel made a lot of difference for starting and general power was to get rid of the supplied combination fuel strainer shut off petcock and put on a standard one quarter inch needle valve, so as to get good flow to the pump. I also remvoed the fuel tank and cleaned thourly. It's been a great tractor and with a few minor Modifications they do a lot of work. bjr
 
   / New Jinma JM304 Electrical Problems #5  
you have a short somewhere or the glow plugs are staying on. When the glow plugs are on it will peg the needle to discharge.
 
   / New Jinma JM304 Electrical Problems
  • Thread Starter
#6  
You're absolutely correct about the short in the glow plug circuit, Dwayne. It shouldn't have mattered, really, since I don't need them here in the Caribbean and pulled the fuse to them, but when checking around I discovered that the buss bar for the glow plugs was shorted against the cowling support bracket. I got that eliminated and then went ahead and yanked the hood and cowling and disassembled the whole harness and then re-assembled it without doing a thing differently than I did the first time. End result was that it started and ran just fine with all systems "go." Cool! I now have a functioning tractor. Time to go get the break-in done and do a few final adjustments, change all its precious bodily fluids and then install the loader - that should bring up a whole new crop of issues. Y'all will be the first to know when they happen.

Thanks for the help everyone!

Rich
 
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