RE: 434 IH Starting

Both small terminals should have wires connected to them. Only one has voltage until you try to start the engine and the circuit is completed when you crank the engine and voltage is fed to the other wire. This the only time you have voltage on both terminals Check the other terminal to see if voltage is present. I think it should be near to the battery cable on your solenoid.

Clean that area where the solenoid attaches to the starter with some emery cloth. Paint & rust make good insulators. Hal

Tim

Does this tractor have a safety switch on the clutch? The 434 that we owned did not but it was an early 434, I know the 384 we had had a starter safety switch on the clutch. The clutch had to be depressed before the starter would engage. This switch caused a lot of problems and most farmers eliminated this safety device.

Now to trouble shoot your start problem with a jumper cable.
BEFORE ATTEMPTING THIS MAKE SURE TRACTOR IS IN NEUTRAL AND REAR BRAKES ARE LOCKED ON AND FUEL CONTROL ROD IS IN THE OFF POSITION.
Test 1:
Now take a single jumper cable and connect one end to the big terminal on the starter solenoid that has the cable from the battery (top terminal), now monentary touch the other end of the jumper cable to the bottom big terminal that is connected to the starter motor, the starter motor should spin but not engage into the ring gear. If it does not spin then there is the following possibilities:
1)Bad connection to battery or battery to ground.
2)Bad starter or starter to ground connection. As I rememember the ground connection to these starters was thru the front end bearing which was not good and later models had a separate ground strap from bottom terminal at the from end of starter to engine block.

If test 1 works then test 2 is same connection as test 1 but this time monentaryly touch the jumper cable to the S terminal on the solenoid.
This time the starter motor should spin and engage in the ring gear. If the starter motor does not spin and engage the ring gear then either the solenoid is bad or the ground on the solenoid is bad.

If test 1 and 2 work then the problem is farther back in the start switch circuit or safety switch or fuse in the start switch line.

Hope this helps
JB2

1}Main battery connection (big nutted terminal). This has two wires on it. One heavy cable from the battery non-ground terminal, and at least one other(usually 10 ga.) going to the Amp meter. (others may be added to this but are not usually correct because they avoid the Amp meter).

2} The "S" terminal (small threaded stud with or without nut). This is the terminal that causes the solenoid to operate. It is not "hot" it is from the start terminal on the key, or start push button. This needs voltage to engage the starter.
The solenoid windings are connected to this terminal on the supply end, and to ground through the solenoid mount on the other end.

3} "I" terminal looks like the "S" terminal (small stud, nut or not). This is a ballast resistor bypass terminal. It is connected to the coil side of the ballast resistor in the ignition circuit. It is connected, on the inside of the solenoid, to the terminal going to the starter. When starting, the battery voltage drops to around 10 volts in cold conditions. To minimize the effects of this reduced voltage this circuit supplies voltage directly to the coil. Helping cold starting in many cases. (this is often ignored and should not be).

4} the Starter terminal (big and with a nut) this goes directly to the starter and causes all actions including engaging the pinion to ring gear. The starter has no other input.

This may clarify the operation of the 4 post solenoid. JimN