2010 DK40 SE Won't Start

[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