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EC240B 81066 Intermittent Fail to Crank

Mark250

Senior Member
Joined
Aug 30, 2015
Messages
1,243
Location
victoria,Australia
Occupation
heavy equipment technician
upload_2019-6-13_8-48-47.png

Figure 1
Wiring diagram SCH01

Marking

Designation

Marking

Designation

BA3101 Battery 1, (12 V, 200 A)
SW3301 Start switch
BA3102 Battery 2, (12 V, 200 A)
RE3301 Start relay
FC01 Fuse, air heater (140 A)
RE3101 Main relay 1
FC02 Fuse, main (80 A)
RE3202 Main relay 2
FU24 Fuse, start switch
MO3301 Starter motor
SW3101 Battery disconnect switch
AL3201 Alternator
RE3201 Resister

   





 

funwithfuel

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Mar 7, 2017
Messages
5,518
Location
Will county Illinois
Occupation
Mechanic
Now we're cooking with gas. All your diodes and relays are in the fuse panel behind the cab . Everything in purple is on the circuit board of the fuse panel. I would start by checking RE3301. Maybe swap it out for another for a quick test. If that doesn't get it, look at the pull coil 85 86. With key in run position there should be power on one side ground on the other. I should have asked this early on, does your fuel gauge work? When you go to crank it passes through the relay to the little relay on the side of the solenoid.
 

Mark250

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Aug 30, 2015
Messages
1,243
Location
victoria,Australia
Occupation
heavy equipment technician
circuit with emergency switch
upload_2019-6-13_18-18-8.png

Figure 1
Wiring diagram SCH03

HE2301 Water separate heater (option)
HE2501 Preheater
SW2301 Water separate switch (option)
MO3301 Starter motor
SW3301 Starter switch
MA2504 Internal exhausted gas recirculation
SW2701 Engine speed control switch
SW9118 Safety lever switch
SW2703 Automatic idling switch
MA910 Safety solenoid valve
SW2704 Emergency switch
SE2701 Engine speed sensor - crank
RE2501 Preheater relay
SE2703 Engine speed sensor - cam shaft
RE3301 Starter relay
upload_2019-6-13_18-23-59.png
   
 

BigBill

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Joined
Jun 13, 2019
Messages
1
Location
Wagoner Okla.
Occupation
Heavy Equipment Mechanic
I have the exact same issue with our John Deere 225 (older unit). I've checked all wiring, test diodes,switches, etc. (all good) Unplug the D+ terminal on alt. Starts fine, but alt light on panel stays on, and hour meter inop. Had to send it out on a job. Waiting for it to come back in for further diagnostics.
 

uffex

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Jan 23, 2012
Messages
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Location
Lincoln UK
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Admin
Good day
The usual way for a alternator fault to show up is that the hour meter will continue to run with the engine stopped and key on.
Kind regards
Uffex
 

007

Senior Member
Joined
Dec 28, 2016
Messages
280
Location
Australia
I find it hard to figure how ac is coming from the D+ terminal.
If you all think it is the alternator pull the wire of as a test and see if the problem goes away.
 

funwithfuel

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Messages
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Location
Will county Illinois
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Mechanic
When the diode trio or rectifier craps out, the a/c voltage begins to leak through. It's very obvious with an oscilloscope. And it will be on the U-batt post not D+
 

watglen

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Location
Dunnville, Ontario, Canada
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Farmer, drainage and excavating contractor, Farm d
Lots of smart people here. Wish I could keep up.

Strongco was out, we worked on it for a day. The conclusion is the VECU is shutting the starter off. If I understand it right, the safety relay at the starter is grounded through the VECU. If the computer wishes to prevent the starter from turning, it simply opens the ground on the safety relay.

That said, about the only thing that we are seeing is an RPM reading during cranking as high as 4000RPM. So the tech started looking at the engine speed sensors. There is one on the crankshaft, and one on the camshaft, and in theory, the computer should be able to run the engine with either one working. The only way to get the engine to crank normally is to unplug both speed sensors. Of course, without a speed indication, the VECU leaves the fuel off, so no smoke.

The Tech ordered a pair of speed sensors and we will try again next week.

He is plugged in, but the crank duration is too short for his laptop to register any useful readings while its cranking. It makes it difficult to diagnose for sure.

Thanks for all the help. Those diagrams posted look a lot like the ones he showed me on his screen, so he must be on the right track.

He was doing all manner of jumping relays etc to overide any faulty component he could. Tested wiring for ground faults, ohms, etc. Speed sensors pass an ohms test, but he needs more complex test gear to really see what they are sending out.

I will keep this thread current as info comes in.
 

007

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Dec 28, 2016
Messages
280
Location
Australia
Thanks for the feed back watglen.
Any chance you can post a close up picture of those two sensors and where they mount on the engine please.
 

mg2361

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Jul 5, 2016
Messages
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Location
Pennsylvania
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Equipment Mechanic
Since I see they are 2 wire speed sensors (reluctance type) you could unplug them so it cranks while having a multi-meter plugged into the sensor set on frequency. Just look for a steady reading while cranking (a little variance will happen as piston runs through compression stroke). If the reading is all over the place you may have a faulty sensor. If you could manage to plug the sensor in and check the same reading at the controller end (may have to pull the wires out of the connector) you should see the same reading there. Different reading then a wiring problem.
 

007

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Dec 28, 2016
Messages
280
Location
Australia
Maybe someone can answer my question then, what are they doing counting the teeth on ring gear or camshaft?
If his laptop is showing ring gear teeth counts the figure would be close to the truth at cranking speed.
The VECU maybe dropping the starter out thinking its time to stop the starter if the sensors are reporting over speed.
Alternatively it still could be nothing to do with the speed sensors as the VECU is not detecting some other critical value like oil pressure and removing the sensors is just tricking the VECU to think engine not turning?
OR the VECU has gone belly up?
 

funwithfuel

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Will county Illinois
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Mechanic
Advise tech to perform active measuring for VECU . Its posted in service side of Prosis. He will be able to see real values without the laptop, but using a breakout box. 4000 rpm cranking? I would pull both sensors and inspect them.
Another thing I remembered, another machine similar to yours but a 290. I found the board in between the 2 of the fuse panel had several burnt traces . If you open the fuse box and climb up there and take a sniff, you'll know. All fuses were powered, all diodes were ok. It was an intermittent start as well. I'm not saying that is it, but worth a look.
 

watglen

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Dunnville, Ontario, Canada
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Farmer, drainage and excavating contractor, Farm d
Well, two new speed sensors and no change. Techs had a 3 way on the phone and its looking like the Engine controller is the issue. Big $$$$ I hope it fixes it.
 

watglen

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Dunnville, Ontario, Canada
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Farmer, drainage and excavating contractor, Farm d
And was that from the flywheel sensor or the crank sensor. Additionally, was this done with alternator plugged in?
I don't know if he knows which sensor the ECU uses to decide the the engine speed, perhaps both. If he unplugs both, it will crank. If he only unplugs one or the other, it won't crank.

He has disconnected the alternator completely, both the heavy battery lead and the 4-pin connector.
 
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