Case IH 16 – Transmission ECM: RANGE (G1) GEAR SHIFT SWITCH SIGNAL VOLTAGE SHORT TO 5 OR 12 VOLTS

The system has detected an abnormally high voltage on the gear shift switch circuit. The fault triggers when the voltage at ECM connector 2, pin 28 goes above 4.2 volts while the tractor is being driven or is in neutral.

• JXC
• Case IH Magnum MX Series (MX210, MX230, MX255, MX285)
• Case IH JXU
• Case IH Farmall series

1. 1

   Check onboard diagnostics menu H9, Channel 17 to verify if the value is above 860 counts

2. 2

   Check onboard diagnostics menu H5 to verify if the display fails to show a transition between d0 and d34 when shifting

3. 3

   Measure the voltage at ECM connector 2, pin 28 (a reading above 4.2V indicates a short to power)

4. 4

   Disconnect the Range (G1) Gear Shift Switch and re-measure voltage at the ECM pin (if voltage drops to normal, the switch is internally shorted)

5. 5

   If voltage remains above 4.2V with the switch disconnected, inspect the wiring harness for a short to a 5V or 12V power source

1. 1

   Safely Park the Machine

   Ensure the tractor is turned off, the parking brake is applied, and the wheels are chocked.

2. 2

   Inspect the Wiring Harness

   Trace the wire from ECM connector 2, pin 28 down to the Range (G1) Gear Shift Switch. Look for rubbed-through insulation, pinched wires, or melted loom that could cause the signal wire to short against a 5V sensor supply or 12V battery power.

3. 3

   Repair Wiring (If Applicable)

   If a short is found, cut out the damaged section of wire, solder in a replacement segment, and seal it with heat-shrink tubing.

4. 4

   Replace the Switch (If Applicable)

   If the wiring tests perfectly but the switch is outputting out-of-range voltage (or failing the H5/H9 transition tests), remove the faulty Range (G1) Gear Shift Switch from the transmission housing and install a new OEM switch.

5. 5

   Clear Codes and Test

   Reconnect all harnesses. Turn the key on and clear the stored fault codes. Cycle the Power Shuttle FNR Lever or Clutch Pedal to re-enable the transmission. Verify that the Transmission Status Lamp is no longer flashing and that the tractor moves normally in all ranges.