Jinma 2840 Electrical Fun....help

[Pstrang]

Picked up a 2004 Jinma 2840 with 215 hours, seems to run good, but has some electrical problems. I'm not the smartest bear in the forest, but know some electrical stuff. Before I start throwing parts at the system, I need some advice. It's a strange electrical system.

1) Doesn't start with key/ignition, but does with a screwdriver across the starter solenoid.

I know ignitions are very suspect for these. Read greg_g's suggestion for a Ford Cold-Start ignition. It's on my list. But the existing one checks out with my ohm meter on a bench. Accessories, Glow plugs, and Starter terminals measure 0 ohms when they should.

Reinstalled ignition. Measure 12.8 Vbat at input, but when I turn to Accessories, it drops to 9.x V, and when I try to start, it drops to 0.3 V. The battery terminal itself still measures 12.8V, so there isn't a short. But the ignition Vbat drops.

2) While tractor is idling, ignition OFF, I measure battery voltage at alternator output (12.8V). But when I turn Accessories on, I'm only measuring 200-300 mV. If I rev the engine, then I can get that up to 0.5 - 0.7 V. But in this ignition position, even the Vbat of the ignition is the 200-300 mV.

These are strange to me. Is there some active component between the fuse box and the ignition input? What is changing the battery voltage when the ignition is switched? The battery does not appear to be loaded down. Otherwise, with that much voltage drop, some wires would be smoking.

3) There are unused wires under the dash going to some 2-terminal can located by the fuse box, horn relay, and regulator. What is this can?

Thanks for all your help!

 

[greg_g]

(1) Probably the clutch interlock switch, located under the left floorboard.

(2) Please explain "vbat"

(3) Unused under-dash wires in a tractor of that vintage would probably light non-existent gauge illumination.

//greg//

 

[Pstrang]

(1) Probably the clutch interlock switch, located under the left floorboard.

(2) Please explain "vbat"

(3) Unused under-dash wires in a tractor of that vintage would probably light non-existent gauge illumination.

//greg//

Thanks Greg.

(1) I checked the clutch safety switch with the ohm meter. Seems fine.

(2) "Vbat" is the battery voltage present at the ignition. Or ignition input. It actually comes from the fuse box.

(3) Okay. Know what that can might be under the hood?

Is it possible to lift the dash? It seems I would need to unbolt steering column, shuttle shift lever, and throttle lever. Ammeter and fuel gauge are also non functional.

Thanks.

 

[greg_g]

My response should have been "replace the keyswitch, then see if you get the same test results".
Short of that:
1. bypass the clutch interlock and see if the keyswitch issue persists (jumper at the plastic connector)
2. might consider replacing the voltage regulator. I did that on my KM454. Got a solid state conversion regulator that mounted right on the alternator. I can look it up if you're interested, but I believe it's a Transpo D7024 universal type
3. two wires into a "can" suggests a circuit breaker, one of those self-resetting types.

Voltage goes through the ammeter on the way to the keyswitch. So given you've got 12v at the switch, it sounds like the ammeter movement is shot. Fuel gauge problems are commonly ground related. There are 2 ground wires: one for the gauge, one for the sending unit. Could be either one. That said, sending units have known to become stuck in one position, and gauges have been known to short out. Needs further troubleshooting.

//greg//

 

[Pstrang]

Thanks! I'll keep probing.

The horn relay is by the fuse box under the hood. The 2-terminal can couldn't be a relay. A relay needs at least 3 contacts. But it's probably related to the flasher control; it's not connected to anything and the flashers don't work. I'll keep playing.

 

[Diamondpilot]

Greg has given you excellent info here. The first thing I would do is bypass the clutch safety switch as he has said and see where you are at. If that changes nothing I would upgrade the key switch. As for the unused wires I have the same tractor and have unused wires also. Which dash do you have? I have individual gauges and the newer tractors have cluster gauges. I have experienced no problems with my wiring other than a bad ground on the battery.

If you alternator is suspect and you decide to change it I would do away with the Jinma alternator and put on a GM single wire unit like so many have done. You can pick up a 10SI alternator for $60 or so at any parts store and its a one wire hookup to the positive post of the battery. You can then lose the Voltage Regulator and all associated components. But that is down the road. Figure out the other stuff like the key first.

Chris

 

[greg_g]

The 2-terminal can couldn't be a relay. A relay needs at least 3 contacts.

My mistake. I knew turn signal relay had one more wire than flasher relay, just counted wrong in my head. As such, I corrected the post above - to suggest instead that it may be a circuit breaker.

//greg//

 

[stevem5215]

Maybe he can get a schematic for it from one of the Tractor dealers on here. I'm sure they'd be willing to fax him one. It would help a lot to diagnose this one.

Steve

 

[Pstrang]

Thanks everyone!

Update: I stopped by NAPA and picked up a $15 regulator. I wasn't sure about the connections, but took a good guess (I thought) based on some google searches. Tractor started right up with the ignition. Great! But the alternator wasn't outputing anything, maybe 0.3V again. I shut off and tried to restart with the key again. No go. So I apparently blew the regulator again.

New regulator was for an old ford; has terminals I (ignition), A (armature), S (stator), and F (field). The alternator has terminals labed '+', 'F', and 'I'. The OEM regulator had 3 connections: 1) Chassis connected to the alternator 'I' terminal, 2) To the 'F' terminal, and 3) To the fuse box through a 10A fuse and out to the instrument cluster with 2 white wires (one goes to the rear light, couldn't find the other).

Based on google searches, the OEM connections, and guesses, I connected the regulator 'A' to the fuse box, 'S' to alternator 'F', and 'F' to the alternator 'I'. Like I said, tractor fired up with the ignition, but just once. Apparently this is wrong because it couldn't do it again.

Thoughts? Advice? (I like the GM alternator option, but then I would lose overvoltage protection on the battery and the ammeter for charging current, well, when I get the ammeter fixed anyway)

Thanks!

 

[Pstrang]

As for the unused wires I have the same tractor and have unused wires also. Which dash do you have? I have individual gauges and the newer tractors have cluster gauges.
Chris

Yes, I have the individual gauges.

You have unused wires too? And do your flashers work? I think that 2-terminal can is the flasher control and it is currently not connected.

 

[greg_g]

Perhaps these diagrams will help. On the wiring diagram:
#5 is the alternator,
#19 is the regulator,
#12 is the ammeter,
#13 is the keyswitch,
#7 is the fuse box
the numbers in () correspond with little ID tags on the wires.

//greg//

 

[Diamondpilot]

Yes, I have the individual gauges.

You have unused wires too? And do your flashers work? I think that 2-terminal can is the flasher control and it is currently not connected.

Yes, everything works fine on my tractor, including all the gauges, lights, ect. I guess I am lucky because my tractor is 7 years old with 800 plus hours and not issues other than a starter, thermostat, and a new battery in that time.

I have not done the GM alternator but many have and it works good. Well I guess I did it on my Ford 861 Tractor 10 years ago when I threw the generator and 6 volt battery away and made it 12 volt with a alternator. I also had to swap the coil from a 6 volt to a 12 volt and change it from positive ground to negative ground. Best money I spent on that old tractor.

Chris

 

[Pstrang]

Perhaps these diagrams will help. On the wiring diagram:
#5 is the alternator,
#19 is the regulator,
#12 is the ammeter,
#13 is the keyswitch,
#7 is the fuse box
the numbers in () correspond with little ID tags on the wires.

//greg//

Wow! That is one valuable schematic diagram. Where did you get that? It is 10x better than the one in the tractor manual. The wire numbers help a lot.

Thank you! This will help with troubleshooting.

 

[greg_g]

Where did you get that?

It's just an updated copy of the one outa my own manual. You can also see it at johnstractor

//greg//