LyHale
New member
I parked my 1991 Ford 1720 and left it for a few days. The tractor was running fine when I parked it. The trouble seems to have begun when I removed the battery temporarily, because I was going to use it in another vehicle. When I put the battery back in, the tractor was dead. No lights on the instrument panel, no nothing.
The battery is a nearly new Interstate with a good 12.7-volt charge; more if I put the trickle charger on it. The cables are clean and tight at both ends. The two neutral start switches are both good, as confirmed with ohm meter. They would not kill the entire panel, anyway. I have the instrument panel off and have just installed an expensive new ignition switch (it seemed like the right solution after spending most of a day crawling all over the tractor with a volt-ohm meter and other tools). The switch is installed correctly. It's an exact match to the old one, and I made a wiring diagram for it before removing anything. I've pulled off connectors and replaced them. I've checked for a fusible link. If it has one, I'm guessing it's the short piece of wire that's attached to the starter solenoid and plugs into the red wire that takes the voltage to the ignition switch. It's hot all the way to the switch, but the accessory and start positions do not get voltage when the key is turned.
There are two clues. One is that the fuses are only getting about 2 volts when the key is turned to the accessory position. The other is that as I fiddle with wire connections and connectors, a couple of the dash lights sometimes come on briefly, but the gauges never get power.
Other 1720 owners refer to a relay. Could a bad relay be the issue? I have the Ford repair manual and the owner's manual for this thing and either I'm blind (possible) or they don't refer to a relay. If my tractor has one, can someone please tell me where to look. There is a small back box with no part number or other identification on the firewall, next to the 3-fuse box. Is that the relay?
Oh, if someone wants a wiring diagram, I'll be happy to send a scanned copy. Unfortunately, the people who drew it did not think it important to name all the parts or include wiring colors.
The battery is a nearly new Interstate with a good 12.7-volt charge; more if I put the trickle charger on it. The cables are clean and tight at both ends. The two neutral start switches are both good, as confirmed with ohm meter. They would not kill the entire panel, anyway. I have the instrument panel off and have just installed an expensive new ignition switch (it seemed like the right solution after spending most of a day crawling all over the tractor with a volt-ohm meter and other tools). The switch is installed correctly. It's an exact match to the old one, and I made a wiring diagram for it before removing anything. I've pulled off connectors and replaced them. I've checked for a fusible link. If it has one, I'm guessing it's the short piece of wire that's attached to the starter solenoid and plugs into the red wire that takes the voltage to the ignition switch. It's hot all the way to the switch, but the accessory and start positions do not get voltage when the key is turned.
There are two clues. One is that the fuses are only getting about 2 volts when the key is turned to the accessory position. The other is that as I fiddle with wire connections and connectors, a couple of the dash lights sometimes come on briefly, but the gauges never get power.
Other 1720 owners refer to a relay. Could a bad relay be the issue? I have the Ford repair manual and the owner's manual for this thing and either I'm blind (possible) or they don't refer to a relay. If my tractor has one, can someone please tell me where to look. There is a small back box with no part number or other identification on the firewall, next to the 3-fuse box. Is that the relay?
Oh, if someone wants a wiring diagram, I'll be happy to send a scanned copy. Unfortunately, the people who drew it did not think it important to name all the parts or include wiring colors.