Case IH 3662 – Engine Control Unit (ECU) / Electronic Diesel Control (EDC): EDC - Level 2 Monitoring: Reported Over Voltage of Supply

The Engine Control Unit has detected that the electrical supply voltage feeding the controller or its monitored sensor circuits has exceeded the maximum allowable safety threshold.

• Farmall
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• Maxxum
• JX series

1. 1

   Perform a battery and charging system voltage test using a multimeter (running voltage exceeding 14.5V–15V indicates overcharging).

2. 2

   Inspect all ground connections for the battery, chassis, and the EDC for corrosion or poor connections.

3. 3

   Check the main power relay for the EDC to see if it is sticking or internally shorted.

4. 4

   Inspect the wiring harness leading to the EDC for chafing, melted insulation, or direct shorts to battery power.

1. 1

   Disconnect Power

   Disconnect the negative battery cable to ensure safety before working on the electrical system.

2. 2

   Clean Grounds

   Clean and tighten all battery terminals and ECU ground connections to eliminate ground-related voltage spikes.

3. 3

   Address Overcharging

   If the diagnostic checks revealed the alternator is overcharging, replace the alternator assembly (or its internal voltage regulator, if serviceable).

4. 4

   Repair Wiring

   If any chafing or shorts to battery power were found in the wiring harness during diagnosis, repair or replace the damaged wiring sections.

5. 5

   Replace Main Relay

   Replace the main power relay if it was found to be sticking closed or operating erratically.

6. 6

   Clear Codes

   Reconnect the battery and clear the fault codes using the Case IH Electronic Service Tool (EST).

7. 7

   EDC Replacement/Reflash (Last Resort)

   Run the machine and monitor the live voltage data. If the fault persists, all external voltages are verified correct, and the wiring is intact, the EDC itself has likely suffered an internal hardware failure and will require replacement or a software re-flash to restore self-learning parameters.