John Deere 002145.09 – PTQ: CAN Bus Message Fault in PTQ

A fault has been detected in the CAN BUS message communication within the Main Control Module (PTQ). Specifically, there is a loss or corruption of expected CAN bus messages from the Front Chassis Control (FCC) unit. This issue affects the proper exchange of data between systems controlled by this module and can lead to the disablement of the PowrQuad transmission system.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6R Series

1. 1

   Check battery voltage and ensure all power and ground connections to the controllers are clean, tight, and free of corrosion (low voltage causes unpredictable errors)

2. 2

   Cycle power by turning the key switch to the OFF position, waiting a moment, and restarting to see if a temporary communication glitch clears

3. 3

   Perform a CAN bus resistance check at the 9-pin diagnostic connector with the battery disconnected (should read approximately 60 Ohms)

4. 4

   Check for shorts by measuring resistance from the CAN High line to chassis ground, and CAN Low to chassis ground (both should be an open circuit/mega-ohms)

5. 5

   Check for external voltage on the CAN lines with the key on (CAN High should be 2.5-3.0V, CAN Low should be 2.0-2.5V)

6. 6

   Inspect the wiring harness between the PTQ and FCC controllers for pinched, chafed, or corroded wires and connectors

7. 7

   Disconnect one controller at a time (PTQ or FCC) to see if the correct 120 Ohm resistance of the single terminating resistor returns to the bus to isolate the fault

1. 1

   Safety First

   Park the machine on a level surface, turn it off, and disconnect the battery before beginning any electrical diagnostics or repairs.

2. 2

   Inspect Harness

   Perform a thorough visual inspection of the wiring harness that connects the PTQ and FCC modules. Look for any obvious signs of damage, corrosion at connectors, or loose connections.

3. 3

   Perform CAN Resistance Test

   Access a known point on the CAN bus, such as the main diagnostic port or a connector for an easily accessible controller. With the battery disconnected, measure the resistance between the CAN High and CAN Low pins.

4. 4

   Analyze Resistance Reading

   If the reading is ~60 Ohms, the main bus and terminating resistors are likely intact. If the reading is ~120 Ohms, there is an open circuit in the bus or one of the terminating resistors (located within a controller) is not connected. If the reading is low or 0 Ohms, there is a short circuit in the wiring.

5. 5

   Isolate the Faulty Component

   If an incorrect resistance is found, consult a machine-specific wiring diagram to identify the locations of the PTQ and FCC controllers. Disconnect the PTQ controller and re-measure the bus resistance. If the reading changes to 120 Ohms (or another expected value based on the network topology), it points towards an issue with the PTQ controller itself. If not, reconnect the PTQ and disconnect the FCC and repeat the test. This process of elimination helps pinpoint the faulty module or section of wiring.

6. 6

   Repair or Replace

   If a damaged wire or connector is found, repair or replace that section of the harness. If a controller is identified as the source of the fault, it must be replaced.

7. 7

   Final Verification

   After the repair or replacement, reconnect the battery, turn the ignition on, and check if the fault code has cleared. Operate the machine to ensure the transmission functions correctly. A new controller may require programming by a certified John Deere dealer.