Case IH 56074 – Transmission Controller (TRANS): Voltage detected on output of Transmission Neutral Latch Relay when it is OFF.

Voltage is being detected on the lockup valve group (specifically 1F, 1M, 1R, 2F, 2R, 5F, 5R, lube, and system pressure) at a time when voltage is not expected to be present.

• STX Steiger
• Puma series
• Puma 125

1. 1

   Test the transmission neutral latch relay for an internal failure (e.g., contacts welded shut/stuck closed, allowing voltage to pass when off).

2. 2

   Inspect the wiring between the neutral latch relay, the neutral relay, and the transmission controller for a short to power.

3. 3

   Test the transmission controller itself to determine if it has failed and is erroneously sending or reading voltage.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to ensure safety while working with the transmission electrical system.

2. 2

   Test/Replace the Relay

   Locate the Transmission Neutral Latch Relay in the fuse/relay panel. Swap it with a known good relay of the same type or test it with a multimeter. If the relay is stuck closed, replace it.

3. 3

   Trace the Circuits

   If the relay is functioning properly, use a multimeter to check the wiring harness connecting the neutral latch relay, neutral relay, and the transmission controller. Repair or replace any wires that are shorted to a 12V power source.

4. 4

   Address the Controller

   If both the relays and the wiring harness pass inspection, the transmission controller has likely failed. Replace the transmission controller and perform the necessary transmission calibration procedures.