Fried my ecm with battery change

retired farmer

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tractor, loader, cutter, blade
May 25, 2020
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sheridan
"plug a small 12 battery into accessory socket to feed power"........
That is apparently how it works with my 2014 MB E350.
Loose all 12V supply, means.....tow it to dealer,.... for complete reset.
A local mechanic uses a 9 volt transistor radio battery connected to a plug that plugs into the lighter socket before disconnecting car battery.
rr
 

chim

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L4240HSTC with FEL, Ford 1210
Jan 19, 2013
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Google "Potential chemical energy"
Did that. I'll admit to not reading everything that came up, but it is generally understood that a fully charged car battery has something approaching 15VDC produced by the "Potential Chemical Energy". That would be open circuit, no load. Without more information, my gut feeling is that damage is caused by reversed polarity during the installation.

I wasn't able to find any indication of the possibility of high voltage produced in a battery. Please share any information I may have missed in that regard. Thank you.
 

GreensvilleJay

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BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
Apr 2, 2019
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Greensville,Ontario,Canada
There are lots of 'coils' in any tractor. Every relay IS a 'coil', every solenoid is a 'coil', every length of wire IS a 'coil'(though very,very low in value). That ECU may have 'coils' connected to every I/O pin ( connection ).
You get the 'spike' when the electrons race from battery to the 'other end' (whatever that is )
How big a 'spike' depends on several factors like length of wire ,actual current flow and 'device' it's going to.
The big problem is not knowing what is actually connected when the battery is attached. ideally nothing, but modern vehicles have radios,alarm systems, GPS, etc. that are powered 24/7. Though they may not draw a lot of current they will create a 'spike' when battery is connected.
I don't know what is 'live' on your machine, though the wiring diagram will show. It gets complicated with OPC modules, engine kill solenoids and other equipment. All of the 'electronics' today is a sealed 'black box' so information is not available.
Bottom line... swapping a battery should NOT have fried the ECU.
 
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ve9aa

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TG1860, BX2380 -backblade, bx2830 snowblower, fel, weight box,pallet forks,etc
Apr 11, 2021
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Did the OP ever tell us if the key was on (by accident) or whether the battery could have possibly been installed reverse polarity?

Either scenario would open up the possibility to damage; possibly severe.

I am no tractor expert (but know my way around electricity fairly well) but I find it curious that the simple act of installing a battery properly (key off) could damage a tractors' (or cars') ECU.
 

Dave_eng

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Oct 6, 2012
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My post is just intended to provide info not to be of help to the owner with a serious issue!!!

It has been my experience studying Kubota and John Deere manuals that John Deere goes to a much greater length to protect against reverse polarity situations. They use special purpose relays called "Safety Relays" and up to 6 diodes combined in a block which is about the size of a relay.

The Safety Relay operation;
Safety Circuit:
A safety circuit consisting of the K3 safety relay 1, and the
V6 diode is installed in the circuit to protect the N1 voltage

regulator/rectifier from reverse battery polarity.

The above is just one description of several safety relays within the wiring harness.

Here is the schematic of the diode block.

Diode block from John Deere.jpg


Dave
 
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