Case IH 36 – Instrument Cluster Unit (ICU), Cab Controller (CCH), or Armrest Controller: Auto PTO indicator lamp bulb failed

The system has detected an open circuit or a lack of current draw on the circuit responsible for illuminating the Auto PTO indicator light, typically caused by a burned-out bulb filament, severed wire, or loose connection.

• MX Maxxum
• MX80C
• MX90C
• MX100
• MX110
• MX120
• MX135
• MX150
• MX170
• MX180
• MX200
• MX210
• MX220
• MX240
• MX270
• Magnum 215
• Magnum 245
• Magnum 255
• Magnum 275
• Magnum 305
• Magnum 335
• Maxxum Series
• Puma Series

1. 1

   Engage the Auto PTO switch (interlocked with the 3-point hitch) and verify if the green Auto PTO indicator fails to illuminate on the dash or A-pillar display.

2. 2

   Turn the ignition key to the ON position without starting the engine to perform a cluster sweep/bulb check. If the Auto PTO light remains dark, the bulb is likely blown.

3. 3

   Ensure the rest of the instrument cluster is illuminating properly. If multiple lights or gauges are out, check the main instrument cluster fuse and ground connections.

4. 4

   If a new bulb does not fix the issue, use a multimeter to test the bulb socket for 12V power and continuity to ground when the Auto PTO is engaged.

1. 1

   Disconnect Power

   Disconnect the tractor's negative battery cable to prevent short circuits while working behind the dash.

2. 2

   Access the Instrument Cluster

   Remove the retaining screws holding the dash panel bezel or side console in place. Carefully tilt the instrument cluster forward to access the rear printed circuit board and bulb sockets.

3. 3

   Remove the Socket

   Locate the specific bulb socket for the Auto PTO indicator (often a small plastic twist-lock base). Twist the socket counterclockwise (about a quarter turn) and pull it out of the cluster.

4. 4

   Replace the Bulb

   Pull the old bulb straight out of the socket. Push the new replacement bulb into the socket. (Note: On some newer models, the bulb and twist-lock socket are a single non-separable unit).

5. 5

   Reinstall

   Insert the socket back into the cluster board and twist clockwise to lock it into place.

6. 6

   Test

   Reconnect the battery, turn the ignition on, and engage the Auto PTO to confirm the new bulb illuminates.

7. 7

   Reassemble

   Secure the instrument cluster and dash bezel back into place.