I'm more of a step-by-step guy and wanted to give you a detailed rundown that might help you as you work through troubleshooting. Much of what I'm going to say here has already been said by other posters, I'm just putting it in more of a 'service manual' format if you will. Follow these steps in order and you should be able to figure out where the problem lies.
Section 1: Starter Voltage Checks
NOTE: All sections will require a volt meter.
1. Ensure that the tractor is in neutral with the parking brake set and STOP cable pulled out.
2. Check that the top post on the starter solenoid is receiving 12+ volts from the battery.
a. If 12+ volts is not present, battery or battery cable is defective or has bad connections. Verify battery voltage and clean battery cable connections and try again. If problem persists with good battery voltage and clean, solid connections, replace cable. If problem persists, report back with findings.
b. If 12+ volts is present, proceed to step 3.
3. Disconnect the small wire from the solenoid tabs (see picture from Hacke). Connect the positive connector from your volt meter to the end of the disconnected wire and the negative end to a good ground. Turn and hold the key switch to the start position. There should be 12+ volts present with the switch held.
a. If 12+ volts is not present, proceed to Section 2.
b. If 12+ volts is present, proceed to step 4.
4. Source a 3-4 foot jumper wire. With the key in the OFF position and the STOP cable pulled out, connect one end of the jumper wire to the positive terminal of the battery and the other end to the solenoid terminal tab. Note that there may be small sparks when this connection is made.
a. If the starter engages and spins over the engine, clean wire connections on the starter solenoid wire, reconnect, and try starting normally.
b. If the starter does not engage proceed to step 5.
5. Using an
INSULATED, thick screwdriver, carefully bridge the top and negative starter posts (items 1 and 4 in Hecke's picture). Be prepared that this will generate a significant amount of sparks and should only be done for a few seconds.
a. If the starter engages and spins the engine over, the starter solenoid is faulty or has bad connections. Clean connections and re-attempt step 4 or replace starter solenoid.
b. If the starter does not spin the engine over and there are no sparks when the connection is made, starter is faulty and should be taken to a service shop for further testing or replaced.
c. If the starter does not spin the engine over but there are sparks when the connection is made, something else is causing issues (could be a number of things I won't expand into in a single post). Post back with your findings for additional guidance.
Section 2: Wiring Checks
1. Remove cowling around the steering column and dash so that you are able to easily access the key switch and connected wiring.
2. Identify if you have a 3-position or 5-position key switch. The 3-position switch will have an off, run, and spring-detent start position. The 5-position switch should have an aux, off, run, spring-detent glow plug/thermostart, and spring-detent start position.
3. Referencing page 2 of the wiring diagram that Hacke posted, identify the wires connected to the key switch. Label the switch or the wires by writing numbers on the switch with a grease pen or wrapping tape around each wire then labeling the tape.
4. Carefully remove the hot wire from the switch (item 10) being sure not to allow the wire end to make contact with any grounds to avoid sparks.
5. With a volt meter set to DC mode, check that the wire is supplying 12+ volts.
a. If 12+ volts are present, proceed to step 6.
b. If 12+ volts are not present, proceed to Section 3.
6. Remove all wires from the key switch. Ensure that wires are marked for later reassembly.
7. Set volt meter to continuity mode. Connect one end of the volt meter to the hot wire terminal on the key switch, and the other to the starter terminal (item 8 in Hacke's diagram). Turn the switch and hold the key in the start position. Verify that there is continuity between the two terminals.
a. If continuity is good, proceed to step 8.
b. If there is no or poor continuity, clean terminals and re-attempt test. If test still fails, key switch is faulty. Replace key switch.
8. Connect one of your volt meter leads to the starter solenoid wire from the key switch, and the other to the starter solenoid wire at the starter. Ensure that the tractor is in neutral and check for continuity through the wire.
a. If there is no continuity, the neutral start switch has failed or is faulty. Try wiggling the shifters around to see if you can get continuity. Replace or bypass neutral start switch.
b. If there is continuity, reassemble and attempt to start the tractor. If tractor starts, your neutral start switch may still be faulty but it managed to get into a good position for the test. Recommend replacing switch or bypassying anyway. If tractor still does not start and there is continuity, report findings and we will go from there.
c. If results are intermittent or inconclusive, try the steps in Section 3.
Section 3: Supplemental Wiring Checks
Some tractors are equipped with additional equipment that, when faulty, can cause the symptoms you're describing. To completely rule out these systems, conduct the following steps:
1. Disconnect the hot wire from the key switch as described in Section 2 item 4.
2. Run a jumper wire directly from the battery positive terminal to the key switch hot terminal.
3. Attempt to start the tractor.
a. If tractor starts, wiring between battery and key switch is faulty. This can be caused by old, worn wiring, corrosion, a faulty fuse, or if equipped, a faulty battery shutoff switch. Post back with results for more instructions.
b. If tractor still will not start, post back with a detailed list of the results of each previous step so we can try and give you more instructions.
Hope this can help! Use the wiring diagrams posted above!
