New Holland 3698 – ECU / EDC: Failure in Glow Plug Cylinder 4

The engine control system has detected a malfunction within the glow plug circuit for cylinder number 4. This can be caused by a failed glow plug, wiring issues, or a faulty glow plug control module. A failure in this system prevents proper preheating of the combustion chamber, which can lead to hard starting in cold conditions, rough idling, misfiring, and increased white or gray smoke from the exhaust upon startup. The glow plug indicator light on the dashboard may also flash, stay on longer than usual, or not illuminate at all.

• Boomer 20
• Boomer 25
• Boomer 3040
• Boomer 3045
• Boomer 3050
• Boomer 4055
• Boomer 4060
• TC25
• TC29
• TC30
• TC33
• TC35
• TC40
• TC45
• TC48DA
• Workmaster 45
• Workmaster 55
• T1510
• T2210
• T2310
• L125
• L140
• L150
• L160
• L170
• L175
• C175

1. 1

   Visually inspect the wiring harness leading to the glow plugs for any signs of damage, frayed wires, loose connections, or corrosion on the connectors.

2. 2

   Verify power delivery by using a multimeter to check that the glow plug rail or bus bar is receiving voltage when the ignition is turned to the 'on' or 'start' position. The glow plug light on the dashboard should illuminate during this pre-heating cycle.

3. 3

   Perform a glow plug resistance test by disconnecting the electrical connector from the cylinder 4 glow plug and measuring resistance between the terminal and the engine block (ground). A healthy plug reads between 0.1 and 6 Ohms; an 'OL' or infinite reading indicates an open-circuit failure.

4. 4

   Perform an amperage draw test using an amp clamp on the glow plug circuit. A typical glow plug draws between 10 and 12 amps; a significantly lower overall reading indicates one or more failed glow plugs.

1. 1

   Prepare the machine

   Ensure the engine is cool to the touch and disconnect the negative terminal of the battery for safety.

2. 2

   Access the glow plugs

   Remove engine covers or other obstructing components to gain access to the glow plugs on the cylinder head. On some models, removing the front-end loader may provide better access.

3. 3

   Disconnect electrical connections

   Carefully remove the nut or clip that secures the power wire or bus bar to the top of the glow plugs. Remove the bus bar to isolate the individual glow plugs.

4. 4

   Remove the faulty glow plug

   Clean the area around the glow plug to prevent debris from falling into the cylinder. Using a deep socket wrench (commonly 12mm), carefully unscrew and remove the glow plug from cylinder 4.

5. 5

   Install the new glow plug

   Compare the new glow plug to the old one to ensure a match. Gently thread the new glow plug into the cylinder head by hand to avoid cross-threading, then tighten it to the manufacturer's specified torque.

6. 6

   Reconnect the electrical system

   Re-install the bus bar and securely fasten the nuts or clips to the new glow plug and the others. Reconnect the main power wire to the bus bar.

7. 7

   Test the repair

   Reconnect the battery's negative terminal. Start the engine to confirm that it starts smoothly and the fault code does not reappear.