New Holland 3692 – ECU: Glow Plug Circuit Power Stage Overtemperature

Fault code 3692 indicates an over-temperature condition within the power stage of the Engine Control Unit (ECU) responsible for the glow plug system. This means the circuit controlling the glow plugs is drawing excessive current, leading to overheating. The system requires a reaction if the failure is not present after a short period of time, indicating that the issue may be intermittent or temporary, and further investigation is needed to determine the root cause.

• TC35
• TC40
• TC40DA
• TC45
• L230
• Case D35
• Case D40
• Case D45

1. 1

   Visually inspect the wiring harness for the glow plug control module and glow plugs for signs of corrosion, loose connections, or burnt/damaged wires.

2. 2

   Test the glow plugs for proper resistance by measuring between the glow plug terminal and the engine ground (a healthy plug should read between 0.5 and 2.0 ohms). An open circuit or direct short indicates a failed glow plug that can cause improper current draw. It is recommended to test all glow plugs, as one failing can be a sign that others may fail soon.

3. 3

   Perform a test light check on the glow plugs by connecting a 12-volt test light to the positive battery terminal and touching the probe to the disconnected glow plug terminal. If the test light illuminates, the glow plug is likely good.

4. 4

   Test the glow plug control module/relay by checking for battery voltage at the input with the key in the 'on' position.

5. 5

   Check for output voltage from the control module to the glow plugs during the pre-heat cycle (when the glow plug light on the dash should be on). Power going in but not coming out, or a voltage drop of more than 0.5V, indicates a faulty module.

6. 6

   Use a diagnostic scan tool to check for other related fault codes (e.g., P0671-P0678) to pinpoint if the issue is isolated to a specific cylinder's glow plug or wiring.

1. 1

   Prepare machine for service

   Turn off the engine, remove the key, and disconnect the negative battery cable for safety.

2. 2

   Locate and access control unit

   Locate the glow plug control unit (location varies by model, e.g., under a side cover on the TC40DA or near the alternator on the valve cover). Remove any obstructions such as the air cleaner assembly or intercooler tube to gain access.

3. 3

   Remove faulty control unit

   Disconnect the electrical connectors from the control unit by depressing the locking tabs. Unbolt and remove the old unit from the engine or chassis.

4. 4

   Install new control unit

   Bolt the new glow plug control unit in place. Apply a small amount of dielectric grease to the electrical connectors to prevent corrosion, then securely attach them to the new unit.

5. 5

   Reassemble and test

   Reinstall any components that were removed for access. Reconnect the negative battery cable, turn the key to the 'on' position, and verify that the dashboard glow plug indicator light illuminates for the appropriate duration before starting the engine.