2010 DK40 SE Won't Start

[k0ua]

Step one:. You know the problem is the fuel solenoid is not pulling back correct? from you prior investigation, so lets try to find out why. The solenoid has 2 coils. the "pull coil" and the "hold coil". the Pull coil draws 32 amps of current that only lasts for about 1 second. This gets the solenoid pulled back, and the hold coil draws about .77 amps and holds the solenoid back. Here are the measurements chart and a picture. I see a discrepencie right now in which pin number is which between the chart and the picture.. But obviously the coil with the low ohms reading will be the high current pull coil terminal and the high resistance coil terminal will pull a small amount of current and be the hold coil.. So look for the 1 second pulse of 12 volts to "pull" and check for the 12 volt hold voltage.. If that does not happen, then lets dig deeper in to the relay. let me know

James K0UA

 

[k0ua]

here are the chart and pix.

 

[TimbourLarry]

Thanks kOua! I have a friend coming over this afternoon and we will work through Step One and report back.

 

[ritcheyvs]

TimbourLarry: While you are waiting for your friend, have you checked the fuses? There appear to be three fuses that effect the stop solenoid, any one of which would cause your symptoms. I'm looking at an EX schematic and they are labeled UNIT, Alternator/Engine Stop, and Engine Stop Solenoid on that schematic. But they may be labeled different on your machine so I'd look for any blown fuse, any fuse with corrosion on the fuse holder, or any fuse that looks like it got hot at either end. Sometimes you can't detect a bad fuse visually in which case try either a known good fuse or tesr the fuse continuity with your new meter.

 

[k0ua]

any news?.. after checking those 3 fuses fuses, take a look at the fuel solenoid pull coil relay.. third relay in on the firewall from the tractors right side.. could be the display unit also. notice on the schematic that the 1 second pull coil pulse comes from the display unit. to the pull coil relays coil... Do you have the Neutral lamp illuminated when you shift the range selector to neutral to start the engine start sequence? Let us know if you dont understand anything we just said.

James K0UA

 

[TimbourLarry]

As suggested I checked the fuses and all checked out fine. After my friend arrived we performed the check James suggested. We checked both the old and new solenoids and they both checked out perfectly. When we plugged the solenoid in and turned on the switch to crank the solenoid did not pull back, however when we manually pushed the solenoid rod in the hold pulse worked fine and it stayed in a retracted position until I turned the switch off. I just read your post from last night about the relay and yes the neutral light does illuminate during the start sequence. the only odd thing occurring on the dash board lights is the red park light never goes off and this started several weeks prior to the "no start" problem. I hope this helps and thanks again for the kind assistance.

 

[Coyote machine]

Are you saying the brake light indicator on the dash is on all the time when the key is in the on, crank, or accessories positions?
This should get checked out to see why it is on. You could start at the switch at the brake pedals and disconnect one wire to see if the light goes out. If yes, then switch is likely bad. I find it hard to see how this might affect the no start condition, BUT by making the light go off, if the tractor can then start you will know you're onto the culprit causing your problem and then we can further assist. Fun stuff! James and I relish doing electrical repairs in cyberspace- don't we James?:confused2::confused3:
One wire at a time, so many wires - where'd they all come from, and so many colors too....:laughing:

 

[k0ua]

Love it it is a challange.. did you check to see if the Pull coil relay on the firewall operates for the 1 second.. Remember look at the schematic I posted and you can see that the coil of this relay is driven by the ground that comes out of the display unit's timer function. the other side of the relay's coil is hot with the key on voltage from the key switch. Remember this ground from the display unit is just momentary (1 second) as the key is turned to the on position. If that relay on the dash does not pull up for that one second then thee pull voltage going to the fuel solenoid will never happen.. Your doing good, keep at it.

James K0UA

 

[kraftykeltic]

Just A thought, but it is pertinent, all connectors are dry. Corrosion does weird things. If you have a connector with wires that you are tracing going through it open it up and check it. When checking for 12 volts with a digital voltmeter you may see voltage, but there may not be any current. Any green in a connector means you have a problem. Remember Dielectric grease is your friend.

 

[k0ua]

Just A thought, but it is pertinent, all connectors are dry. Corrosion does weird things. If you have a connector with wires that you are tracing going through it open it up and check it. When checking for 12 volts with a digital voltmeter you may see voltage, but there may not be any current. Any green in a connector means you have a problem. Remember Dielectric grease is your friend.

This is very good advice.. I would be willing to bet at least half of the electrical problems on tractors are corrosion issues.

James K0UA

 

[Coyote machine]

Hey James, thinking out loud here; what is the possibility that the brake light circuit being on constantly is causing the 1 second pull of the fuel coil to NOT be able to engage? I read where that pulse comes from the instrument cluster, correct? I know it sounds far fetched, BUT the brake switch light should not be illuminated all the time, so maybe there is a circuit board short causing both the light AND the coil to malfunction.:confused3:

 

[k0ua]

Hey James, thinking out loud here; what is the possibility that the brake light circuit being on constantly is causing the 1 second pull of the fuel coil to NOT be able to engage? I read where that pulse comes from the instrument cluster, correct? I know it sounds far fetched, BUT the brake switch light should not be illuminated all the time, so maybe there is a circuit board short causing both the light AND the coil to malfunction.:confused3:

Hm... that is a clue.. I will study the schematic, some and see If I can come up with anything.

 

[k0ua]

Hey James, thinking out loud here; what is the possibility that the brake light circuit being on constantly is causing the 1 second pull of the fuel coil to NOT be able to engage? I read where that pulse comes from the instrument cluster, correct? I know it sounds far fetched, BUT the brake switch light should not be illuminated all the time, so maybe there is a circuit board short causing both the light AND the coil to malfunction.:confused3:

My analysis of the circuit diagram is no, these things should not be related. The parking brake lamp is powered from the ON, key bus and runs thru the instrument cluster, the parking brake switch throws a ground on this lead thru the lamp causing it to illuminate. This does not touch the so called "display unit" module shown here on the engine side of the firewall. It is odd though that the parking brake lamp is illuminated, there must be a ground on the lamp side of the circuit, and I would investigate what is causing this to occur..the parking brake switch is up under the dash on the right side near the parking brake lever.

 

[TimbourLarry]

Thanks guys for all the suggestions and helpfulness. Unfortunately my friend who actually understands the electrical stuff is going to be out of town until next Thursday and I will also be travelling some, so we will perform the suggested tests next week and report back. although I wish I weren't having this problem I feel that I will learn a lot from you about the electrical system which will serve me in the future.
By the way is it ok to run the tractor with the solenoid off and then manually kill it with my finger (if I'm very careful?) have a good weekend.

 

[k0ua]

Thanks guys for all the suggestions and helpfulness. Unfortunately my friend who actually understands the electrical stuff is going to be out of town until next Thursday and I will also be travelling some, so we will perform the suggested tests next week and report back. although I wish I weren't having this problem I feel that I will learn a lot from you about the electrical system which will serve me in the future.
By the way is it ok to run the tractor with the solenoid off and then manually kill it with my finger (if I'm very careful?) have a good weekend.

I don't see any problem with doing that. let us know what you find, PM me if you need to, if I miss the update to the thread

 

[ritcheyvs]

I don't see any problem with doing that. let us know what you find, PM me if you need to, if I miss the update to the thread

I'm not so sure unless you can somehow cap the hole. I believe this hole is open to the crankcase. Diesels always have some blow-by which might blow a oil mist out of the engine through this hole.

 

[k0ua]

I'm not so sure unless you can somehow cap the hole. I believe this hole is open to the crankcase. Diesels always have some blow-by which might blow a oil mist out of the engine through this hole.

OOps.. hadn't thought about that..yeah that could be a problem

 

[TimbourLarry]

I'm finally back after too much travel and got some additional help from my daughter's father in law. We started the multimeter testing from the beginning. He tested the pull terminal which I understand is connected to the blue wire and it pulled just 10 volts for the 1 second which was not sufficient to activate the pull coil. as reported in an earlier post after manually pushing in the rod the hold coil is working properly. That's the latest and again I really appreciate the help from you guys.

 

[k0ua]

I'm finally back after too much travel and got some additional help from my daughter's father in law. We started the multimeter testing from the beginning. He tested the pull terminal which I understand is connected to the blue wire and it pulled just 10 volts for the 1 second which was not sufficient to activate the pull coil. as reported in an earlier post after manually pushing in the rod the hold coil is working properly. That's the latest and again I really appreciate the help from you guys.

Hm... 10 volts instead of 12.6 or so.. gotta wonder if there is a high Resistance connection along the way. Does the battery voltage stay 12.6 when the start cycle is first engaged.. Take readings of voltage along the path from battery top of post to battery clamp thru the relay, both in and out... gotta be a high resistance somewhere causing the voltage drop. Theory time All wires and connections have some voltage drop when they are passing large currents, as in this application where we are expecting to pass 30 amps or so. BUT the voltage drop you are observing is excessive. to the point the solenoid is not being pulled up. Now that being said, remember this is a pulse of only 1 second.. any chance that your meter would not "count up" and stabilize in the short period? You could test that theory by just measuring the battery voltage and counting "one thousand one" and see if it measures the 12.6 volts in time.

 

[TimbourLarry]

James, I ran your theory by Bill who tested the tractor over the weekend and he indicates he used a good quality 20K ohms/V analog multi-meter and saw no deflection above 10 V. He wonders if the bypass diode connected from the 12 V pull-coil terminal to ground might be the problem. When the 12 v DC is applied to the terminal, this reverse biases the diode which should cause a high resistance, very small current, negligable voltage drop across the diode. If the internal characteristics of the diode had somehow changed to allow a higher reverse bias current flow, this might cause the 2 V drop in the pull coil voltage. Since this is likely a solid-state device, it is unlikely that the internal characteristics would change partially (if shorted, we would see 0 V at terminal, if open we would see full12V), so this may be a long shot.
What do you think and any other suggestions? Thanks