Ford 3600, key switch or coil troubleshooting and Education

[Luke0927]

Hello everyone need some education please. Ford 3600 that was running great yesterday, went to run the tractor today and it turned over once and then almost like a fuse pop/click and then no engagement of the starter.

The battery cables have been on my list to replace to I pulled them, cleaned them and it turned over 1 time and did the same click with nothing after.

To rule them out I built new battery cables with new wire, new terminals and ring lands and did a quick charge on the battery.

My question is how to do I properly diagnose a bad key switch vs the coil. For troubleshooting I also have the neutral safety bypassed to rule that out.

I have a 4 wires at the switch, Main power source to fuse link (fuse tested good with volt meter). I have 12.6v on the positive and ground side of the ignition coil and key switch, I also have voltage and ground at the alternator

I'm a little confused what my 4th wire on my key switch is I have main power leg, ground leg, neutral safety wire, 4th wire seems to go to a sensor on the manifold past the 3rd cylinder (picture attached).

With the key in the run position and crossing the power at the coil I still did not get engagement of the starter.

So now I'm wondering could it be as simple as the coil? How would I test this switch I was expecting to see 12v go across the 4 terminal but I do not voltage is very low (that when I ohm/traced the 4th wire to that manifold sensor?)

Could their be a fuse or other wiring issue up the harness I should check? I wanted to get advice before I pull the starter and coil off just to make sure there isn't something I have missed or how I should diagnose.

Appreciate the help.

 

[Sean in PA]

You said:

My question is how to do I properly diagnose a bad key switch vs the coil

You mention the coil, which has to do with the ignition circuit, not the starter circuit. Did you mean the solenoid?

You mention the ignition coil again further down, which makes me think that it has a gasoline engine. There should be no 4th key switch connection if it is a gasser. If it is a diesel engine, then the 4th key switch connection is most likely for the thermostart cold starting aid.

 

[Eman85]

What is the battery voltage at rest? What is it when you try to start?

 

[Luke0927]

Hello everyone need some education please. Ford 3600 that was running great yesterday, went to run the tractor today and it turned over once and then almost like a fuse pop/click and then no engagement of the starter.

The battery cables have been on my list to replace to I pulled them, cleaned them and it turned over 1 time and did the same click with nothing after.

To rule them out I built new battery cables with new wire, new terminals and ring lands and did a quick charge on the battery.

My question is how to do I properly diagnose a bad key switch vs the coil. For troubleshooting I also have the neutral safety bypassed to rule that out.

I have a 4 wires at the switch, Main power source to fuse link (fuse tested good with volt meter). I have 12.6v on the positive and ground side of the ignition coil and key switch, I also have voltage and ground at the alternator

I'm a little confused what my 4th wire on my key switch is I have main power leg, ground leg, neutral safety wire, 4th wire seems to go to a sensor on the manifold past the 3rd cylinder (picture attached).

With the key in the run position and crossing the power at the coil I still did not get engagement of the starter.

So now I'm wondering could it be as simple as the coil? How would I test this switch I was expecting to see 12v go across the 4 terminal but I do not voltage is very low (that when I ohm/traced the 4th wire to that manifold sensor?)

Could their be a fuse or other wiring issue up the harness I should check? I wanted to get advice before I pull the starter and coil off just to make sure there isn't something I have missed or how I should diagnose.

Appreciate the help.

You said:



You mention the coil, which has to do with the ignition circuit, not the starter circuit. Did you mean the solenoid?

You mention the ignition coil again further down, which makes me think that it has a gasoline engine. There should be no 4th key switch connection if it is a gasser. If it is a diesel engine, then the 4th key switch connection is most likely for the thermostart cold starting aid.

Yes I'm probably mixing the terminology up, solenoid sitting on top of the starter. Battery positive wire to the solenoid, and the hot/main fuse link goes to the key switch from the same terminal.

 

[Luke0927]

What is the battery voltage at rest? What is it when you try to start?

12.6v, also put jumpers on it to from my truck running I had possibly thought maybe it has a charge but dropped a cell. It's the long diesel battery AC Delco has some age but even yesterday turned over strong. I could pull it and get it tested to be 100% sure but I would have thought it would have jump started if battery was the issue.

 

[used red MN]

Yes I'm probably mixing the terminology up, solenoid sitting on top of the starter. Battery positive wire to the solenoid, and the hot/main fuse link goes to the key switch from the same terminal.

HIS TRACTOR IS A DIESEL, look at “4th key wire
picture diesel injectors are pictured. Since I am
not a died in the wool Ford guy I am not 100 percent sure but I believe that wire operated a thermal starting device that heats the air in the intake manifold to aid in cold weather starting. Now I see Sean answered that.
In your picture that says “coil wiring” that is not correct that is the “starter solenoid” the highest connection terminal with the screw is what should energize when the starter is turned to the start position. Checking that this is working should be your first step. Additionally this is a short cut, be extremely careful making sure the tractor is in neutral before trying this, this activity has killed people. Jumping from that terminal to the large one just below it should engage the starter. If you get no response, I would suggest getting the battery tested.
To help you with proper terminology I am attaching the manufacturers parts catalog for your tractor. CNHI Ford 3600 parts catalog

 

[Luke0927]

Appreciate the help folks. I'll keep troubleshooting and let you know.

 

[Eman85]

12.6v, also put jumpers on it to from my truck running I had possibly thought maybe it has a charge but dropped a cell. It's the long diesel battery AC Delco has some age but even yesterday turned over strong. I could pull it and get it tested to be 100% sure but I would have thought it would have jump started if battery was the issue.

So it stayed steady at 12.6 at rest and when you tried to start?

 

[Luke0927]

So it stayed steady at 12.6 at rest and when you tried to start?

Well I think you are on to something. I guess I didn't test the battery beyond a charge after making new cables.

I did a charge on it this evening and getting 12.6v, Turning the key to run I drop to 9.x volts, and I drop to 3.6v when turning the key to engage the starter. Sounds like the battery just failed to me? It was perfectly fine day before now lazy/weak start.

 

[Eman85]

Well I think you are on to something. I guess I didn't test the battery beyond a charge after making new cables.

I did a charge on it this evening and getting 12.6v, Turning the key to run I drop to 9.x volts, and I drop to 3.6v when turning the key to engage the starter. Sounds like the battery just failed to me? It was perfectly fine day before now lazy/weak start.

you said you have the big battery, I replaced mine with a smaller H8 AGM battery that works well. Unfortunately you'll probably have to make new cables again.

 

[Luke0927]

you said you have the big battery, I replaced mine with a smaller H8 AGM battery that works well. Unfortunately you'll probably have to make new cables again.

Yes has one of the 4DLT batteries.

 

[Luke0927]

Update for everyone....It was the battery AC Delco 4DLT, had some age on it but started fine the day before and volt meter was showing a charge. Goes to show should always start with the simple stuff 1st. At least it made me learn a few things and put on new cables that I have been putting off.

Appreciate all the help folks.