Case IH 3698 – Engine Control Unit (ECU): Failure in the Cylinder 4 Glow Plug

The system has detected an electrical fault, such as a short circuit to ground, short circuit to battery, or an open circuit in the glow plug circuit for cylinder 4.

• skid steer
• SR250
• TR270
• Farmall 65A
• Farmall 75A
• Farmall 95A
• Farmall JX series

1. 1

   Use the Electronic Service Tool (EST) to confirm code 3698 is active

2. 2

   Inspect the wiring harness and electrical connectors leading to the cylinder 4 glow plug for chafing, melting, corrosion, or loose connections

3. 3

   Use a multimeter to check for a short circuit to ground, short circuit to battery, or an open circuit in the cylinder 4 glow plug wiring

4. 4

   Test the resistance of the cylinder 4 glow plug itself to determine if the internal heating element has failed

5. 5

   Inspect the Fast Glow Plug Control Unit (FGPCU) and its connections, as a failure here can sometimes trigger individual glow plug faults

1. 1

   Prep the Machine

   Turn off the engine, allow it to cool completely, and disconnect the battery to prevent electrical shorts.

2. 2

   Gain Access

   Locate the cylinder 4 glow plug on the engine block. Remove the turbo intake pipe or loosen adjacent pipe connectors for clearance.

3. 3

   Disconnect Wiring

   Carefully disconnect the electrical connection from the cylinder 4 glow plug.

4. 4

   Remove the Glow Plug

   Using the appropriate deep socket, carefully unscrew and remove the faulty glow plug from the cylinder head.

5. 5

   Install the New Part

   Thread the new glow plug in by hand to prevent cross-threading, then tighten it to the manufacturer's specified torque.

6. 6

   Reassemble

   Reconnect the electrical connection to the glow plug. Reinstall the turbo intake pipe and any connectors that were removed for access.

7. 7

   Clear Codes

   Reconnect the battery, use the EST to clear the fault codes, and start the engine to verify the repair.