Case IH 27 – Transmission/Powershift Control System: Neutral lamp not operating.

Loss of voltage to the powershift control circuit, which prevents the transmission controller from verifying the neutral state and operating the powershift solenoids.

• MX Maxxum
• MX Maxxum Series
• MXC Maxxum Series
• MX80C
• MX90C
• MX100C
• MX100
• MX110
• MX120
• MX135
• MX150
• MX170

1. 1

   Check Fuse #34, which supplies power to the powershift thumb switch and the powershift control relays located in the side console

2. 2

   Check the range lever wiring by raising the rubber boot around the range lever and testing for voltage on the #550 Red wire

3. 3

   Inspect the wiring harness going to the range lever and thumb switch for chafed, pinched, or broken wires, as it flexes during operation

4. 4

   Test the two powershift control relays located inside the side console

1. 1

   Verify Power

   Locate and inspect Fuse #34. Replace it if blown. If it blows again immediately, you have a short to ground in the powershift circuit.

2. 2

   Access the Range Lever Wiring

   Lift the boot on the range lever. Using a multimeter, verify 12V power on the #550 Red wire.

3. 3

   Repair the Harness

   If power is present at the fuse but missing at the #550 Red wire, locate the break in the flexible section of the harness near the lever and splice/repair the wire.

4. 4

   Test/Replace the F/N/R Switch

   If the wiring and relays are intact but the tractor still will not shuttle or shift properly, test the F/N/R (Forward/Neutral/Reverse) shuttle switch for internal continuity. Replace if faulty.

5. 5

   Clear Codes

   Use the operator seat switch diagnostic sequence to erase the stored codes. Attempt to drive the tractor to verify that the neutral lamp operates and no active codes return.