looking for some info for my 1068 4020 diesel power shift. with Starter Switch Wiring

[rocklouder]

On my new to me 1968 JD 4020 Diesel Power shift someone had issues with the starter switch so they rigged up a push button on the dash pannel where a choke would be on a gas. Now that doesnt work either. And my only method of starting is with a 6" peice of copper wire with banna clips across the started solinoid. In all my manuals, and books i can not find one single diagram of what this key switch should be or should be wired like properly. Does anyone know of a specific serivice manual or book that has this? I have the original operators manual and a some other service guide but nothing with the wiring diagrams. would the I&T serive manuals have this for a 4020? i know they are pretty detailed on my A's and b's

 

[Jim.ME]

Is it a 12-volt or a 24-volt system?

For a 1968 JD 4020 it looks like you should have JD service manual publication number SM2039 for tractor serial numbers 091000 to 200999. That manual should have the wiring diagrams.

 

[rocklouder]

Is it a 12-volt or a 24-volt system?

For a 1968 JD 4020 it looks like you should have JD service manual publication number SM2039 for tractor serial numbers 091000 to 200999. That manual should have the wiring diagrams.

it is a 12 volt system. thanks i will search out that manual. It still might be in the shop somewhere. My Father-in-law never threw away a manual, but the mice liked them so unfortuanlty i had to toss a couple for some old combines that dont exist. maybe there is hope i will find it before i order one. i did find an original on on the original online auction website but will maybe hold out.

 

[Jim.ME]

If it cranks jumping the starter terminals on a 12-volt system, it sounds like lack of power(current) passing through the starter circuit. It could be resistance in the wiring, starter switch, or neutral safety switch. Does your 4020 have a "Ford" type starter relay mounted such that the wire from the switch goes to that relay and the heavy terminals of the relay energize the starter? JD had a kit that added that relay set up to some tractors due to the type of issue you are experiencing.

 

[rocklouder]

If it cranks jumping the starter terminals on a 12-volt system, it sounds like lack of power(current) passing through the starter circuit. It could be resistance in the wiring, starter switch, or neutral safety switch. Does your 4020 have a "Ford" type starter relay mounted such that the wire from the switch goes to that relay and the heavy terminals of the relay energize the starter? JD had a kit that added that relay set up to some tractors due to the type of issue you are experiencing.

honestly, i have not taken it apart yet. i was busy working on getting the shop ready to paint a farmall H. I was the last tractor my father-in-law didnt finish before he got to the point he couldnt and we thought that if we oculd paint it before he goes, then we could bring it to the nursing home for him to see.

 

[matthies]

The 68 4020's had a push button for starting. The key switch is just on and off, not for cranking. Engine should shut off with the throttle.

 

[Tx Jim]

It would be interesting to know if wiring harness is original 24 volt wiring harness & modified for using only 12 volts or if wiring harness was replaced by an aftermarket wiring harness designed for 12 volts.

 

[Fixingfarmer]

The 68 4020's had a push button for starting. The key switch is just on and off, not for cranking. Engine should shut off with the throttle.

Yes this is correct grandpas is a 68 I think keyed shutoff came the next year

Ours was also converted to 12v long long ago by the dealer I had always wondered if some of the old stock wouldn’t leave until they did. It’s had 2 alternators put on by me over the years and it had a Deere alternator when I took it off.

A powershift will have 2 neutral start switches one on clutch pedal one in transmission a simple test light can help you check that power flows to each and then test the starter solenoid and like said above you will want to find a schematic