Key switch wiring for Diesel with heater, and safety switch.

[Luke0927]

Hello everyone, continuing to work on my ford 3600 3 cyl diesel chasing out some electrical issues and replacing some wiring.

I need to wire in a new switch and my old switch when going to turn the starter over would just drop voltage and not engage the starter ( I would loose all power even at the instrument panel, I may have trouble shoot beyond the switch).

I would appreciate some guidance on rewiring the switch properly, I have the following existing wires on the tractor.

Main Fuse link (battery and Alternator) - 1 wire
Neutral Safety - 1 wire (Was bypassed previously putting in new neutral safety switch )
Intake Heater - 1 wire
Starter solenoid - 1 wire

Key has 3 positions and start - Off, 1 turn, 2nd turn, start

Power is at terminal 1
1 turn of key and I have continuity/power at terminal 2
2 turns of key and I have continuity/power at terminal terminals 1, 2, 4
Turning the key to start I have continuity/power at terminals 3 and 5

Please help me confirm if the wiring below would be correct

Main fuse link will go to Terminal 1.
Starter solenoid should got to Terminal 3 or 5
Heater would go to Terminal 2 or 4
Neutral safety - Which terminal the unused 3 or 5? Need help really understanding how the tractor/switch uses the neutral safety to not start, how does it stop power to starter solenoid if it is not detected, I'm sure some type of open circuit or ground?
Future lights I could wire to which ever terminal does not use the intake heater?

 

[shaun wallace]

Terminal #1 battery, #2 not used, #3 thermostart, #4 gauges, #5 safety switch

 

[Luke0927]

Thanks Shaun I appreciate it going to get a chance to work on this today. Will report back in how it goes, I need to pull the instrument panel and trace out where my power is coming from but based on what you are saying it wouldn't I still need the starter solenoid power off one of those?

 

[Sean in PA]

No, the wire on the other side of the neutral safety switch goes to the solenoid. There is no wire directly from the key switch to the solenoid.

 

[Hacke]

It looks like a five positions key switch, like this:

 

[Luke0927]

No, the wire on the other side of the neutral safety switch goes to the solenoid. There is no wire directly from the key switch to the solenoid.

Thank you that makes sense I was just using my continuity tester to trace wires with the neutral safety wires crossed that makes sense how that all ties in.

 

[Luke0927]

It looks like a five positions key switch, like this:

View attachment 85826

Thank you sir very much appreciated!

 

[Texasmark]

No, the wire on the other side of the neutral safety switch goes to the solenoid. There is no wire directly from the key switch to the solenoid.

The key switch delivers power to things. The safety switch inside the tranny housing controls the ground to the starting solenoid.....not positioning tranny in neutral, no ground, no current path through the starting solenoid, not start............

 

[Luke0927]

Update wondering if I might have a ground issue.

With my volt meter I get continuity between the neutral safety and the starter solenoid like we would expect (wires crossed for testing).

However from the key switch side I'm getting continuity from the wire to temp sensor, and it also shows continuity to the starter solenoid which I believe should not be happening we should not be getting ground then hot from the safety switch?

What also is strange, I have built a new main fuse link and used the original I'm not getting power at my clusters when turning the key, to the 2nd position. When I engage the spring/start on the get I get a quick light up of oil light but now click not engagement of the starter nothing.

I pulled the instrument cluster and did have some debris, which is where my mouse concern comes from. I'm thinking I may need to pull the steering column "hood" to try and investigate better. I'm reading on how to pull that afraid I would have to pull the wheel and I know it has never been removed and could be a challenge.

**Edit from looking at manual, what I was calling temp sensor is actually the oil pressure sender on the left side of block** Will go back and trace out temp sensor wire to document.

 

[Hacke]

Update wondering if I might have a ground issue.

With my volt meter I get continuity between the neutral safety and the starter solenoid like we would expect (wires crossed for testing).

However from the key switch side I'm getting continuity from the wire to temp sensor, and it also shows continuity to the starter solenoid which I believe should not be happening we should not be getting ground then hot from the safety switch?

What also is strange, I have built a new main fuse link and used the original I'm not getting power at my clusters when turning the key, to the 2nd position. When I engage the spring/start on the get I get a quick light up of oil light but now click not engagement of the starter nothing.

I pulled the instrument cluster and did have some debris, which is where my mouse concern comes from. I'm thinking I may need to pull the steering column "hood" to try and investigate better. I'm reading on how to pull that afraid I would have to pull the wheel and I know it has never been removed and could be a challenge.

**Edit from looking at manual, what I was calling temp sensor is actually the oil pressure sender on the left side of block** Will go back and trace out temp sensor wire to document.

Position 3 (first springy position) is for pre-heating, only the Thermostart is engaged.
Position 4 (second springy position) is for cranking and heating at the same time, both Thermostart and starter solenoid are engaged.

One thing to think about with this type of key switch is that there is no position for cranking without the Thermostart engaged. You should not use starting fluid, rag with gasoline or anything else flammable to aid at cold starts, without disconnecting the wire for the Thermostart first.

I do not fully understand what you mean by a ground issue. If you are measuring polarity on a consumer, like the starter solenoid coils tab or a wire that is connected to it, you should read ground. The coils are grounded in the other end and when you apply power to the tab, current will flow through them.

I made a description of the parts you have, as far as we know now. What type of alternator do you have?

 

[Sean in PA]

I'm not sure what you mean by "we should not be getting ground then hot from the safety switch?". If you disconnect the neutral starter safety switch, then neither side of that switch should read hot or ground. They should both be isolated from both hot and ground, and you should be able to read continuity between them only when the hi/low shifter is in the neutral position. If the wires are connected to the rest of the wiring, and the key switch is in the start position and the hi/low shifter is NOT in neutral, then one side of the switch should read hot and the other side should read ground.

 

[Luke0927]

Here is what my starter looks like also what I have been able to trace out.

The thermostat sensor, traces to a green wire with blade connector that connects to the instrument cluster directly.

Intake heater by the manifold directly runs to the key switch.

From key switch, 1 wire sends power to the instrument cluster via blade connector, it also supplies the the positive side power of the oil pressure light bulb, battery charging bulb, and what I think is the dry intake sensor light bulb. This wire I put on terminal 4 to power the cluster.

THIS IS WHERE I'M GETTING CONUSED
That same wire from terminal 4, shows continuity to the starter solenoid. I don't see how this is possibly. I can put my volt meter on OHM with sound and I get connection from the blade connector to my starter?

The safety solenoid wire (terminal 5 on key switch) also shows connection (as expected) from the key terminal wire to the starter solenoid.

This tractor was working perfectly fine until it just seemed to loose all power beyond my main fuse link. I don't believe my power wire to the cluster should be showing a connection to the starter this is what was meaning by could something be grounding or shorting out, but I can not find anything. The only bare spot I have been able to find was on the ground side of the dry intake sensor.

 

[Sean in PA]

THIS IS WHERE I'M GETTING CONUSED
That same wire from terminal 4, shows continuity to the starter solenoid. I don't see how this is possibly.

Measuring continuity is not a good way of checking wiring that you are unsure of, especially when they are connected to other things. One side of the primary of the solenoid is grounded, so the continuity that you are seeing from that terminal on the key switch is likely going through one of the wires on to ground. Remove each of the wires from terminal 4, one at a time, and measure continuity to ground to see which of those wires is providing the path to ground.

 

[Hacke]

Here is what my starter looks like also what I have been able to trace out.

The thermostat sensor, traces to a green wire with blade connector that connects to the instrument cluster directly.

Intake heater by the manifold directly runs to the key switch.

From key switch, 1 wire sends power to the instrument cluster via blade connector, it also supplies the the positive side power of the oil pressure light bulb, battery charging bulb, and what I think is the dry intake sensor light bulb. This wire I put on terminal 4 to power the cluster.

THIS IS WHERE I'M GETTING CONUSED
That same wire from terminal 4, shows continuity to the starter solenoid. I don't see how this is possibly. I can put my volt meter on OHM with sound and I get connection from the blade connector to my starter?

The safety solenoid wire (terminal 5 on key switch) also shows connection (as expected) from the key terminal wire to the starter solenoid.

This tractor was working perfectly fine until it just seemed to loose all power beyond my main fuse link. I don't believe my power wire to the cluster should be showing a connection to the starter this is what was meaning by could something be grounding or shorting out, but I can not find anything. The only bare spot I have been able to find was on the ground side of the dry intake sensor.

I have a diagram that I think is the correct one. If so, your test results matches the correct wiring. For some reason,the wires for oil pressure bulb, oil pressure switch, safety switch and starter solenoid coils are all connected together at the connectors 34 and 35.

Someone more experienced than me is needed to explain why. To me, it looks like there will be a short to ground through the oil pressure switch when you crank, but apparently not so.

Anyhow, I attach the diagram and a detail over the connectors 34 and 35.

 

[Sean in PA]

I have a diagram that I think is the correct one. If so, your test results matches the correct wiring. For some reason,the wires for oil pressure bulb, oil pressure switch, safety switch and starter solenoid coils are all connected together at the connectors 34 and 35.

Someone more experienced than me is needed to explain why. To me, it looks like there will be a short to ground through the oil pressure switch when you crank, but apparently not so.

Anyhow, I attach the diagram and a detail over the connectors 34 and 35.

View attachment 86012

The bulb for the oil pressure warning light provides resistance, so there will not be a direct short through the oil pressure switch when the key is on and the engine is not running. The light bulb will illuminate and there will be a 12 volt voltage drop across the bulb.

 

[Luke0927]

Measuring continuity is not a good way of checking wiring that you are unsure of, especially when they are connected to other things. One side of the primary of the solenoid is grounded, so the continuity that you are seeing from that terminal on the key switch is likely going through one of the wires on to ground. Remove each of the wires from terminal 4, one at a time, and measure continuity to ground to see which of those wires is providing the path to ground.

I do have a test light, that might be a better option to trace back through it. I'll wire it all back up tomorrow and report in.

 

[Luke0927]

Measuring continuity is not a good way of checking wiring that you are unsure of, especially when they are connected to other things. One side of the primary of the solenoid is grounded, so the continuity that you are seeing from that terminal on the key switch is likely going through one of the wires on to ground. Remove each of the wires from terminal 4, one at a time, and measure continuity to ground to see which of those wires is providing the path to ground.

Do you think it is worth pulling the starter and solenoid and testing it out on the bench to ensure it's working correctly, could an internal failure be causing the strange issues?

 

[Hacke]

The bulb for the oil pressure warning light provides resistance, so there will not be a direct short through the oil pressure switch when the key is on and the engine is not running. The light bulb will illuminate and there will be a 12 volt voltage drop across the bulb.

Yes, that is how it usually works but when you crank, you power the wire to the oil pressure switch, which is closed initially. Therefore, you should get a short to ground.

Perhaps there is a resistor in the oil pressure switch. I do not understand why the wires are connected this way.

 

[Luke0927]

UPDATE

I got it going I appreciate all the help gentleman! I learned a lot, best I can tell this intake sensor was somehow shorting me out with the nicked wire underneath the fuel tank hood..

Can anyone tell me what the function of this is, it is wired to a light, light and wiring is good now I've never seen it light up before either.

Also Sean, I used the test light on the starter solenoid it's getting ground with the key off and I'm guessing when going through the starting process that's when key switch/neutral safety sends power and it turns over the starter. I guess I need to do a little learning on how those internals actually work and power and ground actually flow through them.

 

[Sean in PA]

That is officially called the air flow sensor. When the air filter gets too dirty, it restricts the flow of air through the intake, and the vacuum build. When the vacuum gets to a certain amount, the switch closes, which completes the circuit to ground through the bulb and the bulb lights up, which tells you that it's past time to change the air filer.