[iruossim]

I can jump the solenoid with a wrench and the tractor will start with the key turned on. No issues, I can mow the whole yard but once I turn off the key switch I've got to jump the solenoid again to start it.

I had issues mid winter when the brain box terminals were corroded, those got cleaned and dialectic greased. At which time I did all the plugs on the wiring harness.

I've replaced the solenoid, key switch, fuse block. It just won't send juice to the solenoid when I turn over the key switch. Is it a safety switch?

 

[chuckv]

Matthew,

Possibly a safety switch or PTO switch section in the diagram shown here:

Please note that for the 420, the parking brake switch is only on tractors with SN 595881 and above. Also, if you have only the front PTO switch there should be a jumper in the X5 connector as seen here.

Does your tractor have the "starter improvement kit" fitted? If so that relay may have failed.

Absent the starter improvement kit, the conventional troubleshooting for the starter is as follows: Get a voltmeter and start tracing at terminal S2 of the key switch in the top diagram and go counter clockwise until you get voltage when you are in the RUN position.

If you have voltage at S2 in RUN, do you have voltage at the solenoid terminal S when the key is in the START position? If yes, then you have a bad solenoid. If no, then the key switch or its connector will be the issue.

Let us know if you have the relay kit, and we can give additional steps...

Chuck

 

[iruossim]

Chuck, I don't know how to tell if I have the replay kit, any ideas how to tell?

Tractor is an early 1983 model. I'll check, but I'm guessing it doesn't have the brake switch.

I'm currently using both front and read PTO switches.

I'll go check for voltage at the S terminal and let you know.

Thanks

 

[chuckv]

Matthew,

It is absolutely certain that your 1983 tractor does NOT have a parking brake switch.

Both front and rear PTO switches need to be in the OFF position for the starter to crank the engine. If the "starter improvement kit" relay is fitted it usually is mounted on the right side frame near the front cross member if the factory instructions were used.

Chuck

 

[kenworth]

i have john deere 35A rotor tiller and drive shaft for sale.$1500.........call me 913 441 4701 kansas city kansas

 

[bo2009]

Hello Kenneth,
Is OK with me but I believe this particular thread is about\for a 420 not starting.
Do as you wish but if you want responses\replies to a for sale item(s), - you'd be much better off to post in the WFM Classifieds, For Sale section. Good Luck. Bobo

 

[iruossim]

Chuck, I tested the voltage at the key switch and toasted the fuse at F1 (20amp). I haven't been to the local gas station for new fuse yet.

However before it blew I was getting .51 volts at the key switch on the purple wire. So I backed up to the neutral switch and it also had .51 v. Then I checked the pink wire on the key switch and it had 12.43 volts. Is it possible that my issue is yet again in the TCM (brain box)?

When I replaced the key switch, John Deere asked me if it was the early series or the later. Is it possible to have gotten the wrong switch?

Thanks

 

[hankvc]

Matthew, I'll jump in here with a few comments.

First, look at the starting circuit diagram that Chuck posted. Note that the TDC module is not a part of that circuit.

Also, if your tractor is a 1983 tractor with the original B48 engine, it is equipped with a Bendix drive starter. You talk about jumping some "solenoid" to get it started. On the Bendix setup, the solenoid that controls current to the starter motor is on the right side pedestal, under the battery. Just what did you jump from-to? If it was from the battery to the one terminal on the starter, you were bypassing everything. If your tractor has been retrofitted with the 1986-up P218 configuration, then you have a pinion-shift solenoid mounted piggy-back on the starter motor. What is your starter configuration?

To check out the starter circuit through the safety switches, turn PTO's off, transmission in neutral, and turn the ignition on. You should now have 12 volts on both of the transmission microswitch terminals. If not, check the voltage coming out of the 20A fuse; should be 12V.

No voltage at the fuse? Then back up with your voltage tests at points back to the circuit breaker (which is also under the battery).

Voltage at the fuse output but not at the neutral switch? Move forward testing the terminals on the front PTO switch, rear PTO switch, and in/put of the neutral switch. Voltage on one side of the switch but not the other means problem in the switch or its connector.

From the neutral switch, starter solenoid power goes to the ignition switch S2 terminal. The ignition switch closes the starting circuit to the solenoid from the S2 terminal when you turn it to the start position.

That's a quick summary of how the circuit works.
You need to walk through it with a voltmeter to find out where the 12 volt power is vanishing---that's your problem point.

Hank

 

[iruossim]

Hank, Just to make sure I'm reading the same diagram correctly, doesn't the X23 TDC module follow right after the F1 20amp fuse? So the TDC is part of the equation?

I've got 12.43 volts at the 25amp circuit breaker and also on the red wire to the key switch. I'm following 12.43 volts into the TDC on the pink wire out of the key switch, just like the above diagram depicts, then .51 volts comes out of the TDC on the Purple wire. PTO's are off... I'm getting .51 volts on both sides of the PTO switches (front & rear). The transmission neutral switch has .51 volts. I have no brake switch. At X1 (key switch) I have .51 volts. When I hit the key to start the engine I get .51 volts at the solenoid, which isn't enough volts to charge the solenoid for it to make contact to start the engine.

Yes, you are correct, the solenoid and fuse block (25amp circuit breaker) are on the pedestal below the battery on the right (passenger side while sitting in the seat). I've been jumping the current from the battery terminal to the starter terminal with a wrench at the solenoid.

and Yes, you are correct that I have been bypassing all the safety features. That's why I'm here trying to figure out how to resolve this issue. I'm not doing it this way because I'm not trying to be safe, just to get the yard mowed.

I'm doing everything I can think of to resolve the issue and keep the safety features in tact. I could easily make a jumper wire from the key switch to the solenoid or a toggle switch from the battery to the solenoid and forget about this issue all together. But I'm not. Don't take it as I'm trying to bypass the safety features, please.

 

[dkarst]

Hi Matthew, with Chuck and Hank you already have two of the best electrical folks in the world helping but looking at my tech manual, the TDCM is not involved in this problem as Hank mentions. The pink wire runs from key switch to TDC module but then just uses that as common terminal to tie up with the purple wire running to PTO switch. You'd better check your connections to see if something is corroded or loose as the pink/purple have to be at same potential unless something is loose.

 

[hankvc]

As Dennis points out, the connection at the TDC is just a junction in the connector---two wires on the same termination. If you've got 12V at the switch and at the TDC, but nothing to the following X3 connection at the front PTO switch, you've got a fault in the wiring. Make sure that you're looking at the correct wire at the front PTO switch connector. An ohmmeter check at the X3 connector to the ignition switch should show 0 ohms on one wire, unless you have a fault in the wiring between the two points.

Don't sweat bypassing safety features for testing purposes. That is a necessary part of trouble-shooting. What you need to do is do your testing in short steps, so that you aren't trying to guess which wiring link or switch is defective.

Hank

 

[iruossim]

Thanks guys for sticking in there with me. It just fluffs my feathers when someone on here picks a fight over bypassing the safety features. Something I'm inadvertently doing to manage while I've got an issue.

I'll pull the battery tray out and dive in a little deeper. I almost broke down at JD last week and bought a wiring harness.

 

[hankvc]

Matthew, nobody in this thread has picked any fight with you about bypassing safety features.
What we are trying to do is to help you locate where in the chain of safeties you have a fault, so that you can address it directly. The use of temporary jumpers to isolate devices that may be causing trouble is one method for trouble-shooting.

That is very different from telling people that it is just fine to put permanent bypass circuitry
and to work the tractor with a bypass in place.
Not only is this unsafe, but many times when people do this, they butcher and hack the wiring, and generally make a mess of things. This is what is prohibited on this list.

Very doubtful that you need a new wiring harness.
What you need to do is to identify the fault area and fix it. Right now what you need to do is to walk forward through each section of the circuit to see where battery voltage vanishes. That means each section of wiring, as well as across the switches. You've said that you don't have voltage on either side of the neutral switch, so your fault lies somewhere between the ignition switch and the neutral switch. You can use your voltmeter to find where the voltage vanishes, use the ohmmeter to measure across the circuit section, and use a jumper or clip leads to bypass the fault area to verify that you've identified the fault.

Hank