New Holland ENG 527 – ENGINE: Cab pressurization/Ether relay coil circuit shorted high or open

This indicates an electrical fault in the control circuit for either the cab pressurization relay or the ether cold-start injection relay. The Engine Control Unit (ECU) monitors the voltage on this circuit and has detected that the circuit is either open (a broken wire, disconnected plug, or blown coil inside the relay) or shorted high (the control wire is improperly touching a 12V power source).

• TG Series
• TG210
• TG230
• TG255
• TG285
• T9 Series
• STX Steiger
• CR Series
• CX Series
• CX5000
• CX6000
• CX6080
• CX6090
• CR9090
• Magnum
• MX series

1. 1

   Determine if your specific machine configuration utilizes an Ether Cold Start Aid system or a Cab Pressurization system, as the ECU uses the same pin/circuit for these relays depending on the model.

2. 2

   Locate the relay in the main fuse and relay distribution box.

3. 3

   Inspect the relay and its socket for melted plastic, pushed-out pins, or green corrosion.

4. 4

   Remove the relay and use a multimeter to measure the resistance across the relay coil pins (usually pins 85 and 86). If it reads infinite resistance (OL), the relay coil is open and the relay is dead.

5. 5

   With the relay removed and the key ON, check the ECU control wire at the relay socket. If it shows 12V when it shouldn't, the wire is shorted high to another power wire in the harness. Check for continuity between the relay socket and the Engine ECU connector to rule out a broken (open) wire.

1. 1

   Disconnect Power

   Turn off the ignition and disconnect the negative battery cable to prevent accidental shorts during repair.

2. 2

   Access the Panel

   Open the fuse/relay panel where the Cab Pressurization or Ether relay is located.

3. 3

   Replace the Relay (If Faulty)

   If your diagnostic checks proved the relay coil was open (dead), discard the old relay. Apply a small amount of dielectric grease to the terminals of the new relay and seat it firmly into the socket.

4. 4

   Repair the Harness (If Faulty)

   If the relay tested fine but the wiring was open or shorted high, trace the wiring harness from the relay block back to the Engine ECU. Look for pinch points, rub-throughs on the chassis, or damaged connectors. Splice and heat-shrink any broken wires, or isolate wires that have melted together.

5. 5

   Clean Contacts

   If the relay socket is corroded, use electrical contact cleaner and a terminal brush to clean the socket pins before reassembly.

6. 6

   Test and Clear Codes

   Reconnect the battery, turn the key to the ON position, and use a diagnostic tool (or the machine's onboard display) to verify the code has changed from Active to Inactive. Clear the code history.