Case IH 19676 – DCU (Dosing Control Unit): Ambient Temperature: SAE J1939 Check for CAN receive signal : (Signal Range Check: Signal not in range / Erroneous Signal / Signal not available) | SAE J1939 Check for CAN receive signal : (Ambient air temperature not in range) | P0600 Serial Communication Link

The control module is not receiving a valid ambient air temperature signal over the J1939 CAN bus network. The signal is either missing, out of its expected operating range, or corrupted.

• Tier 4a
• Magnum Series 235
• Magnum Series 260
• Magnum Series 290
• Magnum Series 315
• Magnum Series 340
• Magnum Series 370 (Series 4)
• Steiger Series 350 to 600 horsepower models

1. 1

   Check for related codes (e.g., 19677, 3517, 3518, 3519) that might indicate a direct sensor failure rather than a broader CAN bus issue

2. 2

   Inspect the Ambient Air Temperature Sensor (often integrated with the humidity sensor on the air intake/filter housing) for physical damage, heavy dirt/debris, or a disconnected plug

3. 3

   Verify the wiring harness and connectors between the Engine Control Module (ECM), the sensor, and the DCU for chafed wires, open circuits, or corrosion inside the connector pins

4. 4

   Test the sensor's resistance with a multimeter to check for an open load or short circuit

1. 1

   Power Down

   Turn off the tractor, remove the key, and disconnect the battery to prevent electrical shorts during repair.

2. 2

   Locate the Sensor

   Find the ambient air temperature sensor, typically mounted near the engine air intake or air filter housing.

3. 3

   Inspect and Clean

   Disconnect the sensor's electrical pigtail. Inspect the pins for moisture, corrosion, or pushed-back pins. Clean with electrical contact cleaner. If the connector is damaged, splice in a new connector pigtail.

4. 4

   Check CAN Bus Lines

   Inspect the J1939 CAN bus wiring leading to the DCU. Repair any damaged sections of the harness.

5. 5

   Replace the Sensor

   If the wiring and connections are verified good but the DCU still reports an out-of-range signal, the sensor itself has failed internally. Remove the old sensor and thread/snap the new sensor into place.

6. 6

   Reassemble and Clear Codes

   Reconnect the sensor harness and the battery. Turn the ignition on and use an Electronic Service Tool (EST) or compatible diagnostic scanner to clear the 19676 fault code.

7. 7

   Verify Repair

   Start the engine and verify that the ambient temperature reads correctly on the cab display and that the fault code does not return.