450c won't turn off

Post support questions about your JD350 and newer crawler here
User avatar
Rincon
430 crawler
430 crawler
Posts: 58
Joined: Tue Jan 16, 2018 3:00 pm
Location: Las Vegas , NM

450c won't turn off

Post by Rincon » Mon Aug 04, 2025 2:33 pm

Good afternoon.
This is a new one for me. Finished working the roads today. Everything perfect. Get back base camp and 450 c crawler and does not turn off. Had to close off intake for shut down. Replaced alternator today. Ignition switch? Fuel solenoid? Any help would be appreciated. 1976 jd450c. Key switch with push button start.

dtoots1
350 crawler
350 crawler
Posts: 1265
Joined: Fri Nov 30, 2012 8:54 am
Location: akron, ohio

Re: 450c won't turn off

Post by dtoots1 » Mon Aug 04, 2025 5:06 pm

sounds like is deisel??
Or Gas?

User avatar
Rincon
430 crawler
430 crawler
Posts: 58
Joined: Tue Jan 16, 2018 3:00 pm
Location: Las Vegas , NM

Re: 450c won't turn off

Post by Rincon » Tue Aug 05, 2025 4:56 am

Diesel

User avatar
Stan Disbrow
350 crawler
350 crawler
Posts: 2983
Joined: Fri Jul 15, 2005 3:13 pm
Location: Raleigh, NC

Re: 450c won't turn off

Post by Stan Disbrow » Tue Aug 05, 2025 6:54 am

Hi,

Yank the wire off the fuel solenoid. If it quits, the key isn't dropping power. If it keeps running, the solenoid is stuck.

Stan
There's No Such Thing As A Cheap Crawler!

Useta Have: '58 JD 420c 5-roller w/62 inside blade
Useta Have: '78 JD350C w/6310 outside blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Have: 1950 M, 2005 x495, 2008 5103 (5045D), 2025 3025E

User avatar
Rincon
430 crawler
430 crawler
Posts: 58
Joined: Tue Jan 16, 2018 3:00 pm
Location: Las Vegas , NM

Re: 450c won't turn off

Post by Rincon » Tue Aug 05, 2025 3:44 pm

Thanks Stan. Is my solenoid above the filter? Or down left side forward by the timing ?

Jim B
350 crawler
350 crawler
Posts: 2439
Joined: Sun Nov 05, 2017 11:36 am
Location: western Maine

Re: 450c won't turn off

Post by Jim B » Thu Aug 07, 2025 6:17 am

The fuel shut off solenoid is inside the injection pump. Look for a wire coming to a stud terminal on the top of the injection pump.

Did you put the OEM type Motorola alternator with regulator on it or change it to something like a Delco 10SI 3-wire type? If a diode, indicator light or resistor is not used in the exciter wire of the Delco 3-wire type, they can back feed to the ignition switch and prevent shut down of gas engines or diesels with electric shut off solenoids.

User avatar
Rincon
430 crawler
430 crawler
Posts: 58
Joined: Tue Jan 16, 2018 3:00 pm
Location: Las Vegas , NM

Re: 450c won't turn off

Post by Rincon » Sat Aug 09, 2025 5:20 am

The alternator is a 3 wire. I pulled the wire off the pump and the engine shut off. So now I know that the solenoid is still good. Interesting that the excitor wire would affect it. This morning I will disconnect the excitor wire and see if it shuts down with it disconnected. If does, would I be forced to put a kill switch on the injector pump wire?

Jim B
350 crawler
350 crawler
Posts: 2439
Joined: Sun Nov 05, 2017 11:36 am
Location: western Maine

Re: 450c won't turn off

Post by Jim B » Sat Aug 09, 2025 5:55 am

If you pull the exciter wire off and it will shut down, I would be looking for the problem, not adding another switch. If this started with your alternator change it is most likely there is an issue with something related to that.

You did not answer my question on what brand alternator, 3 wire is not a brand. If you changed from the OEM Motorola with a regulator to a Delco internally regulated "3-wire" type, there is at least one wiring change, or it will do just what you are encountering. The details are needed to help you.

User avatar
Rincon
430 crawler
430 crawler
Posts: 58
Joined: Tue Jan 16, 2018 3:00 pm
Location: Las Vegas , NM

Re: 450c won't turn off

Post by Rincon » Sat Aug 09, 2025 6:48 am

Changed to delco

Jim B
350 crawler
350 crawler
Posts: 2439
Joined: Sun Nov 05, 2017 11:36 am
Location: western Maine

Re: 450c won't turn off

Post by Jim B » Sat Aug 09, 2025 6:40 pm

It very much sounds like back feed from the alternator is the problem. Details of what you did are needed to point you to things to check. The more info you can provide about what you did the easier it will be to figure out the problem and may save some questions.

Did you change from the OEM Motorola alternator with the regulator to the Delco type?

Did you have a wiring diagram for what you did?

What did you change for wires? Did you run a new wire to the #1 (excitation terminal) spade? If so, where does it get its power?

User avatar
Rincon
430 crawler
430 crawler
Posts: 58
Joined: Tue Jan 16, 2018 3:00 pm
Location: Las Vegas , NM

Re: 450c won't turn off

Post by Rincon » Mon Aug 11, 2025 7:33 am

The B+ D+ tach and ground wires are original wires from the old alternator. They are hooked up accordingly on the new alternator. This is what I don't understand other than being a bad ignition switch? I have one coming. My excite wire D+ does not have current with ignition off..

User avatar
jimmydiesel
440 crawler
440 crawler
Posts: 177
Joined: Tue Oct 26, 2021 10:23 am
Location: North Central Washington

Re: 450c won't turn off

Post by jimmydiesel » Mon Aug 11, 2025 8:08 am

Is it possible the new alt. Is actually a 1 wire.
If it is the alt. would keep working after the ignition switch is turned off.
Check the part #, they look the same the only difference being the internal regulator.
440 ICD 602 Blade 3Pt.hitch.
440 ICD 602 Blade Gearmatic winch.
440 ICD 64 6 way Blade Carco winch
440 ICD 831 Loader
440IC 831 Loader
1010c Diesel 612 6 Way Blade
North Central Washington State

Jim B
350 crawler
350 crawler
Posts: 2439
Joined: Sun Nov 05, 2017 11:36 am
Location: western Maine

Re: 450c won't turn off

Post by Jim B » Mon Aug 11, 2025 10:12 am

What is the brand and part number of the alternator you installed? Most Delco types do not have a tach terminal.

The excite wire should not have power when the key is off. When the key is turned on, the switch sends power to excite the alternator (current flows to the alternator). If you had an indicator light in series in the excite wire to the alternator, the light comes on as the alternator acts as a ground for the light circuit. When the alternator starts charging the alternator puts power out the excite terminal back towards the switch and the light goes out as there is now power on both sides of the indicator light, it has no ground. When the key is turned off, the indicator light acts as a check valve and prevents that power from the alternator's excite terminal from going back to the switch. That back feeding power from the alternator can keep a gas engine ignition system going, or an electric fuel shut off open, if not stopped before it reaches the switch. When there is no indicator light in that circuit a diode or resistor is needed to stop that current going back to the switch.

With the engine running and the key shut off, does unplugging the excite wire from the alternator let it shut down? If so, you need to add a diode in that wire.

A one wire alternator would not keep the engine running unless you ran the big alternator battery wire to the switch. or there was an issue with where the tach signal is going.

I am not saying your switch might not be bad, but the excitation circuit has bit many in the past and should be checked to be sure that is not the issue.

User avatar
Rincon
430 crawler
430 crawler
Posts: 58
Joined: Tue Jan 16, 2018 3:00 pm
Location: Las Vegas , NM

Re: 450c won't turn off

Post by Rincon » Fri Aug 15, 2025 3:28 pm

Thanks for your info Jim. I'm only working on the 450c when I come to the ranch. I think I got the wrong alternator for this conversion. I am going to get a 10sI delco from napa tomorrow. Someone on here had a schematic for the wiring. I'm assuming the existing voltage regulator can still be used?and I'm assuming that two wires won't be used.? Other than the larger red wire. ? And a jumper wire. And one back to the acc on switch. ? When I bought this crawler 6 years ago it didn't have a functional volt meter meter. I'm going to put one on as well. It has been a work horse.

Jim B
350 crawler
350 crawler
Posts: 2439
Joined: Sun Nov 05, 2017 11:36 am
Location: western Maine

Re: 450c won't turn off

Post by Jim B » Fri Aug 15, 2025 5:57 pm

To install a Delco type 10SI alternator, you eliminate the old external regulator; a Delco type 3-wire alternator has an internal regulator. (The 1 wire version has an internal regulator as well.)

The output post of the alternator gets a 10- or 12-gauge wire back to the same terminal on the solenoid the positive battery cable hooks onto.

The number 1 spade terminal (one on the left when looking at the back of the alternator needs a power wire to excite it. You may be ok if it is alone on the Acessory terminal of the switch. If it is on the same terminal as your fuel pump solenoid it needs a diode, incandescent indicator light, or a resistor in series between the switch and alternator terminal. 14-gauge wire is large enough.

The number 2 spade terminal (one on the right when looking at the back of the alternator) the wire from it can run right to the alternator battery post. It senses system voltage for the internal regulator to function. 14-gauge wire is large enough.

With a wiring diagram and test light you should be able to reuse the current battery wire to your alternator. You may also be able to pick out the old excite wire and reuse it by installing a diode in it.

Unlike an ammeter, your new voltmeter will connect to a switched power source and the second wire goes to ground.

Post Reply

Who is online

Users browsing this forum: Google [Bot] and 6 guests