CLAAS Id769Eh / 769Eh (531) – TR3 (Transmission 3) Module: Short-circuit at the 12V of the automatic rear PTO engaging contact

The system detects an improper 12V signal on the circuit for the automatic rear PTO switch (component code S172), resulting in the rear PTO automation becoming inactive.

• Axion 810
• Axion 850
• Axion 920
• Axion 950
• Arion 410
• Arion 420
• Arion 430
• Arion 510
• Arion 640

1. 1

   Check for a possible short-circuit to 12V in the wiring harness connected to the automatic rear PTO engaging contact (S172)

2. 2

   Test the automatic rear PTO engaging contact (S172) itself for internal short-circuits

3. 3

   Test the TR3 (Auto 5) module to see if the internal circuitry has failed

1. 1

   Power Down

   Turn off the tractor's main switch and wait at least 30 seconds before beginning electrical diagnostics.

2. 2

   Locate S172

   Locate the automatic rear PTO engaging contact (S172) in the cab controls.

3. 3

   Test the Harness

   Disconnect the S172 switch. Using a multimeter, check the signal wire leading back to the TR3 (A57-3) module for continuity to power (12V). If 12V is present on the signal line while disconnected, trace the harness to find and repair the chafed or melted wire causing the short.

4. 4

   Test the Switch

   Test the S172 switch for proper continuity when toggled. If the switch is internally shorted to its 12V supply pin, replace the switch.

5. 5

   Replace the Module

   If the harness and switch both pass inspection, the fault lies within the TR3 / Auto 5 module. Replace the module and perform any necessary software calibrations.