Case IH 21 – Electronic Draft Control (EDC) Module or Electronic Hitch Control (EHR) Unit: Draft Sensitivity Control Voltage Low (Short Or Open Circuit)

This code indicates that the signal voltage from the draft sensitivity potentiometer has dropped below the acceptable threshold. This is typically caused by a broken wire (open circuit), a wire shorting to ground, or a complete internal failure of the potentiometer itself.

• MXM
• MXM120
• MXM130
• MXM140
• MXM155
• MXM175
• MXM190
• 7200 Series
• MX210
• MX230
• MX255
• MX285
• 235-340 (Series 4)
• Puma Series
• Maxxum Series
• Steiger Series

1. 1

   Visually inspect the rear hitch control panel wiring pigtail at the draft sensitivity potentiometer for disconnected plugs, pinched wires, or corrosion.

2. 2

   Perform a harness continuity and short test by disconnecting the potentiometer and EDC controller, then checking the signal wire for continuity and shorts to ground.

3. 3

   Perform a wiggle test on the harness and connectors while checking continuity to identify intermittent circuit breaks.

4. 4

   Test the potentiometer by measuring resistance across it while slowly turning the dial, ensuring resistance changes smoothly without dead spots.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent electrical spikes.

2. 2

   Access the Control Panel

   Remove the trim panels on the right-hand operator console to expose the underside of the hitch control panel.

3. 3

   Remove the Faulty Component

   Disconnect the electrical connector from the draft sensitivity potentiometer. Pull off the adjustment knob from the top of the console, unbolt the retaining nut, and remove the potentiometer.

4. 4

   Repair Wiring

   If your diagnostic checks revealed a broken or chafed wire in the chassis/console harness, splice and heat-shrink the damaged section.

5. 5

   Install New Part

   Insert the new potentiometer into the console, secure the retaining nut, press the adjustment knob back onto the splined/slotted shaft, and plug in the electrical connector.

6. 6

   Reassemble and Calibrate

   Reinstall the console trim and reconnect the battery.

7. 7

   Hydraulic Lift Calibration

   After repairing EDC components, you must clear the fault codes and perform a hydraulic lift auto-calibration.