Case IH 13 – Electronic Hitch Control (EHR) unit or Armrest Controller: Drop rate control voltage high (damaged potentiometer or short to +12 Volts)

This code triggers when the control module receives a voltage signal from the 3-point hitch drop rate potentiometer that exceeds the normal operating range. The underlying condition is usually an internal failure of the potentiometer itself or a wiring harness issue where the signal wire has shorted to a +12V power source.

• MXM
• Magnum 7100
• Magnum 7200
• MXM120
• MXM130
• MXM140
• MX
• CX
• Maxxum
• Puma

1. 1

   Inspect the wiring harness connecting the drop rate potentiometer to the hitch controller for rubbed, pinched, or melted wires that could cause a short to +12V.

2. 2

   Disconnect the potentiometer, turn the key ON, and use a multimeter to check the signal wire on the harness side for a short to +12 Volts.

3. 3

   Test the potentiometer resistance across pins A to C. A healthy drop rate potentiometer should read 10,000 ohms (10k ohms) ± 10%. If it reads open or out of this range, it is internally damaged.

1. 1

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

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

2. 2

   Access the drop rate control knob assembly, typically located on the armrest control console or the right-hand side control panel.

   Access the drop rate control knob assembly, typically located on the armrest control console or the right-hand side control panel.

3. 3

   Carefully unplug the electrical connector from the drop rate potentiometer.

   Carefully unplug the electrical connector from the drop rate potentiometer.

4. 4

   If the wiring harness tested faulty (shorted to +12V), trace the harness back to the EHR/Armrest controller and repair or replace the damaged section of the wire.

   If the wiring harness tested faulty (shorted to +12V), trace the harness back to the EHR/Armrest controller and repair or replace the damaged section of the wire.

5. 5

   If the potentiometer failed the resistance test, remove the retaining nut or mounting screws holding the potentiometer to the console panel and remove the faulty unit.

   If the potentiometer failed the resistance test, remove the retaining nut or mounting screws holding the potentiometer to the console panel and remove the faulty unit.

6. 6

   Install the new OEM potentiometer and secure it to the console.

   Install the new OEM potentiometer and secure it to the console.

7. 7

   Reconnect the electrical connector and reassemble the console trim.

   Reconnect the electrical connector and reassemble the console trim.

8. 8

   Reconnect the battery and power on the tractor.

   Reconnect the battery and power on the tractor.

9. 9

   Clear the stored fault codes.

   Clear the stored fault codes.

10. 10

    Perform the Electronic Hitch Calibration procedure as outlined in your specific model's service manual so the controller can learn the sweep of the new potentiometer.

    Perform the Electronic Hitch Calibration procedure as outlined in your specific model's service manual so the controller can learn the sweep of the new potentiometer.