Case IH 3694 – ENGINE module: Glow Plug Circuit. - Short Circuit To Ground Error For Low Voltage System.

This fault indicates that the engine's control system has detected a short circuit to ground within the glow plug heating circuit. Because the glow plugs operate on a low-voltage system managed by a dedicated control unit, a short to ground prevents the glow plugs from heating properly. This typically results in symptoms such as hard starting (or a no-start condition), rough idling, engine misfires, reduced engine power, and increased fuel consumption.

• Farmall
• skid steer
• ISM-DI engines
• F5C engines
• F5H engines
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• SR250
• SV250
• Puma
• Maxxum
• Steiger

1. 1

   Inspect the wiring harness running from the Glow Plug Control Unit to the individual glow plugs for chafed insulation, melted wires, or pinch points that could cause a short to ground.

2. 2

   Disconnect the electrical leads from the glow plugs and use a multimeter to test each glow plug for an internal short to ground.

3. 3

   Check the connections at the Glow Plug Control Unit for corrosion or water ingress.

1. 1

   Disconnect Power

   Disconnect the machine's battery to prevent electrical spikes or further damage to the ECU during repair.

2. 2

   Repair Wiring

   If the diagnostic checks revealed damaged wiring, repair or replace the affected section of the glow plug wiring harness.

3. 3

   Replace Faulty Glow Plugs

   If one or more glow plugs tested as internally shorted, remove and replace them. (Note: It is often recommended to replace glow plugs as a complete set if one has failed).

4. 4

   Replace the Control Unit

   If the wiring is intact and the glow plugs test fine, the fault lies within the Glow Plug Control Unit. Replace the unit.

5. 5

   Reassemble and Reconnect

   Reconnect all glow plug leads, control unit harnesses, and finally the battery.

6. 6

   Clear Codes

   Connect the CNH Electronic Service Tool (EST) or a compatible diagnostic scanner to clear the 3694 fault code from the Engine ECU.

7. 7

   Test Operation

   Start the engine to verify the repair. Ensure the engine starts smoothly without misfires or rough idling.