Ford 1720 Grounding / Electrical questions

[ng5783]

We picked up a 1988 Ford 1720 that's having issues. The first thing I noticed after opening the hood is that the battery positive terminal cable is connected to the frame. Could a 1720 really be positive-grounded?

My next question is whether anyone's got experience with electrical starting problems. The ignition switch does nothing when we turn the key, yet the battery reads 12Volts, and the starter turns strong when we put a screwdriver across the terminals on the starter solenoid. The three fuses appear fine. Are there other hidden fuses or fusible links in the wiring for a 1720? Any help would be greatly appreciated!

 

[Texas Blues]

Is the positive cable still connected to the ground? My 1700 is not a positive ground system, I dont know for sure if your 1720 should be either. Voltages should pass throught the ignition switch to the solenoid wire on the starter. I assume that that voltage is not present when you turn the key. Are there any neutral safety switches? If you can get to the back of the ignition switch, you can check voltages with a meter. Does you glow plugs heat up? I guess you would have noticed any burned wire harnesses, I wonder if someone connected the positive cable to the ground by accident and fried something that way? Good Luck, TB

 

[JC-jetro]

1720 is negative ground for sure, something is fishy there. I'd follow Tex's comments to gather more pertinent information. Report later of your findings to narrow it more. Can post wiring diagram if needed. Can you get the tractor started?

JC,

 

[stuartshomepc]

We picked up a 1988 Ford 1720 that's having issues. The first thing I noticed after opening the hood is that the battery positive terminal cable is connected to the frame. Could a 1720 really be positive-grounded?

Take a second look at the battery and cables.

If for some reason the prior owner had to replace the ground cable, which on mine is a braided strap, he may have grabbed something from the auto parts store. It may be a red wire, but look at what connection it makes to the battery. It should not be a positive ground system.

Stuart

 

[Hooked_on_HP]

When you jump the started will it start? Check for safety switches on the clutch, pto and on the trans if it is a hydro. It is a neg ground. If it is hooked up as a positive ground by mistake will the started turn backward???
Bill

 

[RickB]

All battery power except for that which actually powers the starter motor passes through a fusible link. Fastened in parallel with the incoming battery cable on the start solenoid, it has red insulation and is about 3" long with a spade connector on the other end. As stated, this tractor is negative ground.

 

[ng5783]

Thanks for all the helpful posts. After correcting the battery cabling (to negative ground), and replacing the fusible link, which was no doubt zapped when the battery was installed incorrectly, we were able to start the tractor - by shorting across the starter solenoid with a screwdriver. Next task is to learn how to diagnose the starter solenoid and to figure out what the broken wires are that we found after removing the panels under the steering wheel. I guess we'll need to buy a service manual to re-check all the wiring. Thanks again everyone!

 

[JC-jetro]

I guess we'll need to buy a service manual to re-check all the wiring. Thanks again everyone!

Attached you can find wiring diagram for 1710 unit from F044 (IT manual). It makes no reference to 1720 but you might find it useful or close enough for component identification.

JC,

 

[ng5783]

Thanks JC-jetro. The diagram gives me some ideas of things to look for, starting with locating the starter safety switch. Anyone know where it's located? Anyone also know if Ford put in wires for the optional lighter, even if the lighter option wasn't included? Maybe those could be the apparently unused/broken wires sitting near the floor under the steering column?

 

[JC-jetro]

Thanks JC-jetro. The diagram gives me some ideas of things to look for, starting with locating the starter safety switch. Anyone know where it's located? Anyone also know if Ford put in wires for the optional lighter, even if the lighter option wasn't included? Maybe those could be the apparently unused/broken wires sitting near the floor under the steering column?

You're welcome. Starter safety switch is a normally open switch (I.e an intenal spring keeps the switch in open position). Upon pushing the clutch down the N.O switched is closed completing the starting circuit that includes battery, starter and safeties. On some tractors you may have a Seat sensor to force the operator to start tractor sitting on the seat. Obviously, all the safeties can be by passed that is not at all recommended. The switch somehow is manipulated by the clutch release pedal that always is on the left side of the tractor. I'll add couple of pics to help out.


JC,

Using a test light to test out the switch. you can see some adjustment can be done.