New Holland ENG 3693 – ENGINE: Glow Plugs: Short Circuit to Battery Error for Low Voltage System

The engine control system has detected that the voltage in the glow plug circuit is unexpectedly high, indicating a short circuit to the battery voltage. This prevents the glow plugs from operating correctly, which can lead to hard cold starts and excessive white smoke during startup.

• L220
• L223
• L225
• L318
• L320
• L325
• L328
• L330
• L334
• SR175
• C227
• C232
• C327
• C332
• C337
• C338
• C345
• CR9090
• CX8080 Elevation
• CX8090 Elevation Tier 4A

1. 1

   Turn the ignition switch OFF. Inspect the glow plug wiring harness for chafing, melted insulation, or exposed wires that may be shorting directly to a 12V power source.

2. 2

   Test the glow plug relay and associated fuses in the rear fuse box. A stuck-closed relay can continuously supply battery voltage to the circuit.

3. 3

   Turn the ignition switch OFF. Disconnect the glow plug connector. Measure the resistance between the glow plug terminal and a clean chassis ground (ensure the ground connection is free of paint, oil, and dirt). The resistance should be approximately 1 Ω (Ohm).

4. 4

   Verify the connections to the UCM/ECU connector to ensure there is no corrosion or pin damage causing a bridge to a power circuit.

1. 1

   Disconnect Power

   Turn off the ignition and disconnect the negative battery cable to prevent accidental shorts or ECU damage.

2. 2

   Repair Wiring (If Applicable)

   If the diagnostic checks revealed a shorted wire in the harness, splice and heat-shrink the damaged section, or replace the glow plug wiring harness entirely.

3. 3

   Replace the Relay (If Applicable)

   If the glow plug relay is stuck closed, pull the old relay from the fuse/relay block and install a new OEM relay.

4. 4

   Replace the Glow Plugs

   If the glow plugs failed the resistance test: Disconnect the electrical bus bar/wiring from the top of the glow plugs. Carefully unthread the glow plugs from the cylinder head (penetrating oil may be required). Thread in the new glow plugs and torque them to the manufacturer's specification. Reattach the electrical bus bar/wiring.

5. 5

   Clear Codes

   Reconnect the battery, turn the key to the ON position, and use a diagnostic tool to clear the ENG 3693 fault code.

6. 6

   Test Operation

   Start the engine and verify that the cold start lamp functions normally and the fault code does not return.