Black wire to ecu housing

   / Black wire to ecu housing #1  

Dvettrn

New member
Joined
Jul 29, 2025
Messages
3
Tractor
Mahindra 2638
First time posting, first tractor, trying to find some answers before I have to take it to a dealer. 2638 with 160 hrs, didn’t want to start, solenoid clicking, smelled wire burning, found black wire prob #18 to ecu housing w insulation burnt off. Traced wire back to display panel ohmed it out 85 from ground it is not a chassis ground. It’s not burnt through, rewrapped it, started right up ran great. Sat for a week, difficulty starting again, same clicking, open hood and same wire hot as h*ll. Turned off switch, then back on and cranked right up road it home from getting diesel, any ideas or know what that black wire does, floating ground, battery ground? Noticed ecu is not grounded to chassis it’s
 
   / Black wire to ecu housing #2  
Just checked my 2538 (same as yours only earlier model) and the wire from the ECU doesn't go back to the dash panel, but rather down to the frame on the right side under the engine compartment. It is a grounding wire for the ECU, along with several others grounded to the frame at the same point. You might want to check to insure the bolt that connects these grounds to the frame is tight, and also a tight connection on the ECU. (My ECU is in front of the radiator on top right)

Your clicking noise sounds like its the starter solenoid. It may too, have a bad connection on the ground. How old is the tractor? If it's over 3 yrs old, you may need to get a new battery.

I don't think the ECU ground wire getting hot is the cause of the clicking. I think that is collateral damage to your solenoid issue.

Just my 2¢.
 
   / Black wire to ecu housing
  • Thread Starter
#3  
Thx much for the reply, I actually traced the wire, it appears it goes to that stack of wires on the rt side frame to ground but doesn’t as I pulled it out of that plastic accordion cover and all the way to the left side bundle. Mine is a 2024 bought used with 50 hrs on it. I agree with you on solenoid, think it’s either causing the problem or a result of.
 
   / Black wire to ecu housing
  • Thread Starter
#4  
Have an update called the local dealer , awesome folks at east rutherfordton Mahindra, the service tech said the tractor was searching for a ground to start and found ecu wire which means there’s lose chasis ground to battery negative. Bolt was tight on the bundle to right front chasis, however unbolted it anyway and found rust, dust and patina on connectors and thick paint behind it. Cleaned it up and wired brushed the paint off, reconnected and bam started right up x3.
 

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