B7200 - No Lights, No Glow, No Crank

[NoJacketRequired]

It's been awhile since I last posted here. Life has been good, although with summer weather my orange tractors haven't been getting much of a workout since they are primarily snow movers.

This past weekend I had the B7200 HSD out for a run. Started easily, ran well, all appeared normal. The next day I started it, ran it for about 5 minutes, moved it and shut it down. Again, all appeared normal. An hour later I tried to start it to move it back into the shed and I got a nasty surprise. Pushed in the clutch, turned the key to the GLOW position for 20 seconds, then noticed the fuel gauge needle hadn't moved. Moved the key through the "RUN" position to the "START" position and got nothing, not even a click. Returned the key to the "RUN" position and noticed oil and amps lights were not illuminated.

Battery voltage was sitting at a lovely 12.58Vdc. Battery terminals are securely connected (well, one isn't now as I removed the ground terminal in order to begin troubleshooting). Before removing the ground wire I measured the same 12.58V on the starter solenoid terminal.

I've looked at the wiring diagram in the B7200 OPS manual and for the life of me I can't read that diagram. Even with glasses and a magnifying glass the image quality of the PDF version is just too poor to be useable.

I'm reaching out to the great gang here in hopes you might be able to point me in the right direction for a good probable cause for what appears to be a near-total electrical failure. Thanks in advance for your helpful replies.

 

[85Hokie]

Have the mice had a field day? Is there a main fuse?
Try another battery just for S & G's - see if anything changes.
Can jump solenoid also - quick bypass and see if the battery is at fault or something else.

 

[NoJacketRequired]

I might be making some headway on the wiring diagram, thanks to some good posts on this forum. The battery is definitely good (stays up well above 12V with an automotive headlight load applied to it). In the wiring diagram I see the machine is wired so the battery + lead goes to the starter solenoid, then power for the rest of the tractor comes off that solenoid post to a fusible link before distribution to all other loads. Given that I have what appears to be a totally dead electrical system, there's a good chance the fusible link is at fault. Now I just need to figure out where that link is located in the tangle of wires, and what its amperage rating might be.

 

[twomany]

I believe that link is right on the starter connection.
At least there is something similar on the B7200 I have.
The fuses are just under the fuel tank on the left side of the tractor.

 

[Tooljunkie]

You are doing voltage tests to chassis ground, correct? Turn key on and test at starter again using a bare metal engine part as ground. Could show voltage and drop out under load.

 

[twomany]

The link is rated 200 amp according to the operator's literature. And to confirm, the fusible link is located at the starter motor connection.

 

[D2Cat]

"The link is rated 200 amp according to the operator's literature."

Sounds like it's protecting a welder not a tractor charge system!!

 

[sheepfarmer]

It's been awhile since I last posted here. Life has been good, although with summer weather my orange tractors haven't been getting much of a workout since they are primarily snow movers.

Glad your back, winter is regrettably looming yet again! Was beginning to think we'd have to call out the Mounties. Sorry that it is a problem that brings you back, though.

 

[twomany]

"The link is rated 200 amp according to the operator's literature."

Sounds like it's protecting a welder not a tractor charge system!!

What is the CCA rating of the battery fitted?

No sense putting a choke on anything. ;-)

Of course, It's the 10 and 20 amp fuses protecting the wire harness.

 

[tractor2017]

Have you checked you grounds,you can use a booster cable from the battery to a good engine ground.Pull the ignition switch out with the wires still connected and test with a light or volt meter ,if you have nothing there go to the starter connection and start back testing till you have no power. Confirm you have power with the key on at the fuse panel .

 

[Dave_eng]

Your fusible link might look like this one

Dave M7040

 

[NoJacketRequired]

Thanks for all the very helpful posts, folks and your kind words of welcome, sheepfarmer.

A few minutes of digging around revealed what I'll call some "electrical idiocy". That's what happens when somebody who doesn't understand electricity at all gets in there and starts hacking and slashing the wiring. Well, in this case it was only the fusible link that had been hacked.

Under a wad of electrical tape I found a pair of red-ish wires which had been twisted together, poorly. The electrical tape had been intended as the mechanical bond to keep the wires together. Over time and exposure to heat from the close proximity to the exhaust manifold, the bonding force applied by the tape to hold the wires together weakened. The day of the "no lights, no glow, no crank" was the warmest day I had operated the tractor, pushing 30 degrees C. That extra heat was likely the straw that broke the camel's back. The loosely-twisted wire ends separated, thus interrupting the supply of power to the rest of the tractor.

The other night I returned to the tractor and, after finding this tape-covered wad of badness, squeezed it with my fingers and saw the instrument panel lights come to life. Easy temporary fix. Now that I know what's been going on with this connection I can surmise my poor warm-weather starts were likely a result of this flaky connection not passing sufficient juice to really heat up the glow plugs. Two and two have finally been put together, and the answer isn't three!

I'll cobble together something like Dave_eng's photo and re-install it with the wires pointing aft, getting them away from the heat of the exhaust, zip-tied to the bundle to keep them where I put them. Should be good for another 100,000 miles...

Again, many thanks for the helpful suggestions.

 

[D2Cat]

You should be able to find a fusible link to fit in there. Most auto parts stores have them.

 

[Dave_eng]

Just don't use a regular wire. Fusible links are smaller in diameter than you expect and secondly, the insulation is designed to withstand the wire melting and still keep the ends of the wire from grounding.

It could be replaced with a modern slow blow fuse.

Dave M7040