John Deere 4520/Cab

[eepete]

Did a search in the tech manual for "mercury" and "cut-off". Nothing for mercury and nothing relating to the cruse control for cut-off.

Looking at the schematics and pictures of the components, one more thing to check comes to mind:

The switches for the cruise control (and in fact many of the switches in the operator area) are standard spade lug push on connections. I've seen times when the push on part won't fall off the spade lug, but it is loose because the metal on the female push on part is not tight enough or got damaged during crimping. It can work OK, but if jolted just right can cause problems. Most of these switches are read by software in the microprocessor periodically, for example 10 times a second. If you get a jolt at the "right" time, the computer won't see it. If you get one at the "wrong" time, it will see it and think the state of the switches has changed. This means you are chasing an intermittent problem that is made worse by the sampling process.

In the case of the cruise control switch, the "off" position is an open circuit (both cruise control option and auto style option). So a loose wire due to bouncing would look like the cruise control had been turned off, which is the behavior you're seeing.

Just a guess here, might be something to check out, no guarantees. If you find a push on female spade connector that is loose but not falling off, remove it and use a pair of needle noise pliers to _gently_ close the gap on the edges _just_a_bit_ so that when it is plugged in the connector is snug/tight. This is a delicate, gentle, not typical tractor kind of force you use.

It is also possible that the switch is flakey bad. All the usual dilemmas of "buy a new one to try out this guess" or not... It's a single pole double throw switch, but if it's flakey and only fails during "thromping", it might be hard to determine if it's a switch problem, might be easier to try a new switch ?

And finally, if any Deere engineers are reading this, you guys should never use a open as a valid state on a switch. Run the switch into an A2D like the alarm people do. Then you can tell the difference between on, off, and open circuit (cut wire or intermittent). If you're really good, you'll make it so that if you short the input from the switch to ground, that's an invalid state too so you can see shorts to ground. End of geek rant...:confused2:

Pete

 

[jenkinsph]

Pete,
Years ago I worked for a small two way radio shop and would sometimes short the inputs on a little sinader to quiet it. The shop owner got irritated and was concerned that it might damage it.:laughing: Didn't work for him very long, instead became one of his competitors.

 

[eepete]

On the automation stuff I'm working on, one of my rules is you should be able to tie any wire to any wire. So inputs and outputs should be able to be shorted to power or ground or each other. I also design so that these connections are able to tolerate jingle juice (ringing phone line). Works for owners, installers, techs, and fumble fingered engineers .

This whole business of robustness of a design regarding shorts and wrong connections is a new and troubling area. Along with that, the concept of being able to tell if a switch is working or open/shorted is another troubling area. There is a very minor cost savings in not doing these things. But the robustness of the design, reduce down time, reduced false readings, etc. make it worth it. If you get the wrong MBA manager in the design process you get a flakey product. And of course it is very hard for the end user to know if it's done right or not.

The installer can destroy the best of intentions too. Some alarm systems use an "end of line" resistor so they can tell if the wire has been cut, much like the concern I have about the cruise control switch connection. I've seen _most_ systems installed with the end of line resistor at the alarm panel which defeats the function most of the time. Deluxe system with idiot installer.

On these 4000 series, the controller can tell if a light bulb is blown. The chips that drive the bulbs can tell if there is an open. Many of them can also tell if there is an over current (caused by a short). You then get a message on the charactor-challanged display (Err xxx where xxx is the right error code). If the inputs from the switches had the sorts of things I was talking about, the tractor could identify if there was a problem with the wiring harness or switch. So electronics tractors have some evolution that has yet to come.

Hope the OP isn't upset that I'm a bit off topic here, more geek rant... Maybee the dealer can give you a switch to try for "free", since the tractor is new and under warranty and that's his cheapest way to diagnose and possibly fix it?

Pete

 

[vsumoski]

sinader?

 

[jenkinsph]

sinader?

A fairly inexpensive instrument used to determine the signal to noise ratio. Instead of using a more expensive signal generator this can be clamped across the speaker outputs on the receiver and allows you to tune the radio front end for best signal to noise ratio.

 

[tconnors]

Gentlemen:

Thanks for all the input. I did some further testing and questioning.

First of all, a fellow that helps me hay did all the raking the other day and I did a couple of rounds just to see what he was talking about and I was able to find a spot where the cruise control shut off.

He did tell me one thing that makes some sense. He also had the cruise control cancel on him on a downgrade on the highway back to the house which makes me think the weight of the rake was causing the speed to overrun the max setting. I can see that causing a cancellation of the cruise just for safety sake.

To test that theory, I took the tractor out with nothing attached and went over mounds and bumps with the cruise on and no cancellation.

I think this is just a fact of life with this system and I would rather have it this way than to keep the cruise engaged as i drove off into a ditch or something.

Thanks for all your thoughts.

Terry Connors

 

[radman1]

Gentlemen:

He did tell me one thing that makes some sense. He also had the cruise control cancel on him on a downgrade on the highway back to the house which makes me think the weight of the rake was causing the speed to overrun the max setting. I can see that causing a cancellation of the cruise just for safety sake.

Terry Connors

I don't think they are that sophisticated. I have run down many hills and on the road pulling loads and the cruise does not shut off. In fact, it would be dangerous to have the cruise shut off in many instances. Releasing the HST quickly could result in the tractor sliding to a stop when traveling at road speeds when towing a trailer or an attachment. I still believe there is something wrong with your cruise. I would keep after the dealer to fix it or take it to another dealer. The dealer can get tech assistance from JD and they should be able to find the problem. Intermittant issues like yours are always harder to solve and the dealer knows it may take time and various approaches to solve it. It is under warranty and while it is an annoyance now, it could be a hazard in the wrong conditions. I had a JD 3720 and now a 4520 and neither had the cruise problem you describe.

 

[mburke121]

I tend to rest m arm close to the cruise on/off switch, and inadvertently hit.the"off" switch in bumpy terrain.

 

[ddivinia]

Another 4520 working picture.

D.

 

[ham]

That is an astounding price since the Deere dealer in Billings quoted a cabbed4720 with 400CX mirrors, air cushion seat(standard), rear wiper, rear lights, ehydro with ePTO, R4 tires, and NO rear SCV for 47,200$. When I configure on the online site that is pretty close. So I keep wondering where these phenomenal prices and claims of 20% off etc are coming from. I have really pushed the Bozeman and Billings dealers about these and they are stumped. They are adamant that Deere doesn't allow huge discounts across the US to keep prices consistent. They did get a fraud alert from John Deere about pseudo dealers in the Midwest advertising and selling such but never delivering.

So my question is...did you ever really take delivery of this set up? It seems too sweet even without all the extra goodies. If you did maybe it would help all of us if you would scan and place your actual bill of sale with details and dollars so we could prove to other dealers we are not nuts. After all they get a blue book we can't have

Thanks