Case IH 19308 – Engine Control Unit (ECU) / Engine Control Module (ECM): Timeout Error of Frame sent to Heater control unit (HCU)
Issue description
A Controller Area Network (CAN) communication error where the ECU is expecting a status message from the HCU over the CAN bus but is not receiving it, indicating a loss of communication.
Applies to these machines
5 machines- Tier 4b
- T7 Series Tractors
- N-Series Loaders
- Tractor Loader Backhoes
- Machines equipped with the CNH F5 T4B engine family
Check the cause
Verify the machine's battery voltage is within the normal operating range, as low voltage can disable powerstage diagnosis and cause CAN modules to drop offline.
Disconnect the HCU and use a multimeter to verify that the module is receiving proper system power (12V/24V depending on the machine) and has a clean, low-resistance ground.
Check the CAN High and CAN Low wires between the ECU and the HCU for open circuits, short circuits to ground, or short circuits to power.
Inspect the HCU and ECU harness connectors for pushed-out pins, corrosion, or moisture intrusion (DEF fluid is highly corrosive and can wick into wiring harnesses).
Repair steps
Power Down
Turn off the ignition key and disconnect the negative battery cable to prevent electrical spikes.
Access the HCU
Locate the Heater Control Unit, which is typically mounted near the DEF tank header or DEF pump module.
Repair Wiring
If the diagnostic checks revealed a broken wire, corroded pin, or bad ground, repair the harness or replace the connector pigtail.
Replace the HCU
If power, ground, and CAN continuity are all verified as good, the HCU has failed internally. Unbolt the HCU, disconnect the electrical connectors, and install the new unit.
Reassembly and Clearing Codes
Reconnect the battery. Connect the Electronic Service Tool (EST) to the machine's diagnostic port. Turn the key to the ON position, clear the inactive fault codes, and monitor the 'AdBlue/DEF pump heater state' on the EST to verify that CAN communication with the HCU has been restored.
Parts you might need
(1)DEF Heater Control Unit (HCU) / AdBlue Heater Control Module
The exact CNH part number varies heavily depending on the specific Case IH machine model, cab configuration, and engine displacement. You must look up the specific HCU part number in the Case IH Electronic Parts Catalog (EPC) using the machine's exact PIN/Serial Number. When replacing the HCU, ensure that the DEF line heater connectors are fully seated, as the new HCU will immediately run a resistance check on the heater lines upon startup.
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