Foton FT404 electric fuses problems

[traktorz]

The Foton Europard TB404-X161Y1C has been running now more than 700 h over nearly 5 years almost trouble free.

At current winter times the tractor is equipped with chains and during a road maintaining work with a grader blade suddenly smoke from the electric fuses and relays area occurred. Also the fuses for the engine preheat and position lights are blown. The starter solenoid needs to be manually moved from run/stop positions.

These fuses are blown again when replaced, so next step was to get the tractor home and in the garage and next is to look into the wiring and relay problems.

I'm curious to hear if any of you have experienced electrical circuit problems, what the problems were, and how you cured them, on your Foton tractor, or similar to our 40 hp model.

I also would like to have access to the electric diagram in PDF format, is that available for download some where?

 

[greg_g]

Begin at the starter solenoid, and trace every centimeter of your positive (+) battery cable all the way back to the battery. My guess is that you'll find a burned spot in the cable covering where it's been shorted to ground (makes contact with frame, engine, radiator, et cetera).

//greg//

 

[Rich Waugh]

From what I read on the forums, about 90% of the electrical problems on Chinese tractors can be traced to the voltage regulator. Mine gave me fits and lots of blown fuses until I replace my alternator with a Delco 12Si and got rid of the OEM regulator. No problems since.

 

[traktorz]

As the next step to remove the instrument cover, we first need to remove the steering wheel, in order to track down the electrical wiring. As a starter the FEL is now taken off the tractor.

- Where is the voltage regulator on this tractor?
Is it on the relay socket panel, and marked 2.5 VOLTAGE ADJUSTER in this diagram?

Also what function does the "2.3 MAIN POWER RELAY" have?

Is it the "7 STARTING RELAY" that is connected to the solenoid at the diesel injector pump for start/stop maneuvering?

 

[greg_g]

I think you misunderstood. I meant inspecting the positive (+) battery cable (typically red) all the way between the starter solenoid (a physical component of the starter assembly) and the starting battery or batteries. It feeds all electricals during startup, so should be the initial focal point. If insulating cable cover is burnt or worn to the point that copper is exposed - and that copper contacts metal - major fuses will blow.

If no problem found, move on to secondary circuits: first the key start circuit. Turning the keyswitch to the START position typically provides 12v to the starter relay, which in turn engages the starter solenoid, which in turn connects the starting battery with the starter motor. A burned or bare wire contacting metal in that path will also blow major system fuses.

I'm not sure about 2.5, I expect the VR to be under the bonnet: typically on an engine bracket or firewall, or physically integral to the alternator. start the engine and observe the voltmeter reading. Then pull the 2.5 device and see if there's a voltage change on the meter. If yes, then it may in fact be the VR

Main power relay 2.3 may in fact be an upgrade to the "major system fuse(s)" I mentioned earlier. It may be failing in its job to protect those fuses

//greg//

 

[quicksandfarmer]

It looks like your Foton uses the same fusebox as my Jinma, in which case the voltage regulator is on the fusebox, on mine it's silver in color.

I think your symptoms are consistent with too high voltage. One of the things you wrote is that the starter motor was stuck in the engaged position with the flywheel, which gave me an odd idea. When a DC motor is spun it acts like a generator, so I'm wondering if what was happening was that your starter motor was being spun by the flywheel, which was causing it to generate electricity and was overpowering the electrical system. The voltage regulator wouldn't come into play because all it does is regulate the output of the alternator.

Now, in order for that to happen the starter solenoid has to be engaged, otherwise the starter would be electrically isolated from the rest of the electrical system. The other thought I had is that you said that the glow plug fuse was blown. Both the starter and the glow plugs run through the key switch. Is it possible your key switch has failed?

So here's the summary of my hypothesis: key switch fails and energizes starter solenoid and glow plugs. Energized starter solenoid causes starter to engage, and it acts like a generator because the engine is running. System voltage increases, causing anything that is on to draw more current than normal, leading to a bunch of blown fuses.

 

[traktorz]

Foton FT404 : Cable harness burning - long await for spare parts

Here's an update on the electrical problems with our Foton FT404 tractor.

We've been ordering the main relay, the ignition key, and the cable harness through our Swedish importer. The two first items, the importer had in stock, so those we had through the post, the very next day. Regarding the harness, that is a big disappointment with this Chinese Vendor named Foton Lovol.

Still waiting after more than two months, with no signs from the Foton Lovol Factory on expected shipping dates! It seems that the small customers in Northern Europe aren't on this Chinese's priority list.

In the mean time, we've been temporary repairing the cable harness, by cutting out and replacing the burned and broken wires.

Finally, we did attach the wiring to the battery again and went throug a test sequence. All the lamps, horn, sensors and instrument seems to be working. However, when turning the ignition lock to the "HEAT" position, the 30A fuse blow. Checking the wireing to the last connector before the glow plug quartette, the cabling seems OK. Hence our conclusion is that one or more glow plugs are short circuited.

Another problem is that the starter solenoid doesn't respond, althoug there is an additional voltage appearing when moving the ignition key to the "ON" position.

At this warm weather currently in Sweden, using the preheat isn't necessary, so with the corresponding fuse blown and removed, we decided to try starting the tractor. With the starter solenoid removed, we had to rig the fuel pump valve into the running position by a piece of wire.

- The tractor started instantly, it sounded OK, but to stop it, we had to release the rigged wire at the diesel injection pump. The conclusion is that we can run the tractor, but there are some remaining questions, in addition to await the spare part cable harenss from China...

Question 1:
How can I function test a glow plug? What is the nominal DC resistance? Does it need to be replaced with an exact Foton part or is this a commodity item, easily available at other places?

Question 2:
How can I function test the starting solenoid? It has a connector with four wires, although the cable harness only utilizes three wires. What are the wiring schematic for it?

Question 3:
The ignition lock has 5 positions:
OFF - ACC - ON - H - ST
What does ACC stand for, and what is expected to be connected at this position? Is the starting solenoid engaged first at the ON position?

Ref :
♦ Foton Lovol International Heavy Industry Co.,Ltd.
♦ Foton Lovol International Heavy Industry Co.,Ltd.

 

[greg_g]

1. 30 amps (presumed) across 4 glow plugs at a nominal 12.2 volts. Although we already know Chinese wiring doesn't reliably deliver actual battery voltage. But sticking with basic math and Ohm's Law (I=V/R) one can extrapolate that the four GPs represent a total of 0,4067 ohms resistance Plugging that into the equation for parallel resistance reveals that each plug "should" present a nominal 1.6265 ohms. Given the specificity of the resistance, I recommend a matching set of four original equipment plugs. They may not be branded Foton, but that's less important than getting the right diameter/thread count/resistance in four identical plugs.
2. Get a digital multi-meter and a helper. Set the meter to measure DC voltage, on a scale appropriate to detecting 12 volts. At the solenoid, put the (+) lead on the connector to which the clutch bypass wire is attached. Connect the (-) lead to the closest good earthing point (bare metal or battery post/cable). Have helper crank starter, observe voltage while cranking.
3. Accessories, and I've seldom seen a Chinese tractor come from the factory with anything attached there. Use it for radio/auxiliary lighting/et cetera. And no, the solenoid isn't energized until ST.

//greg//

 

[traktorz]

R40-T404-028 EL-STO

Great thanks for your appreciated comments.

The glow plugs should be quite easy to check, when time permits. Still I'm a bit puzzeled why they did break? Measuring each's resistance parameter should give an idea.

My phrasing "starter solenoid" is maybe wrong. It's more of a linear motor pushing or pulling a wire to stop the diesel injection pump.

R40-T404-028 EL-STOP

Found out that the electrical stop (mounted on the diesel injection pump) box was broken, since it didn't respond to the voltage from the ignition key. Ordered it through the country distributor, and had it the next day in the post. Happy to tell, the tractor seems to coming back to it's normal electric conditions again.

One problem remains though, and that is the broken glow plugs. I have sprayed WD-40 thin oil on them, hoping that's gonna help removing them after some days.

 

[Rich Waugh]

Re: R40-T404-028 EL-STO

Great thanks for your appreciated comments.


One problem remains though, and that is the broken glow plugs. I have sprayed WD-40 thin oil on them, hoping that's gonna help removing them after some days.

View attachment 376725

I've found that the best penetrating oil is a 50/50 mixture of automatic transmission fluid and acetone. WD40 is really a poor penetrating oil.