John Deere 3597.06 – OIC / CAB, PL3, or ECU: Current Too High

Current Too High on a switched supply voltage or output circuit, which typically indicates a short to ground or a failed component drawing excessive amperage. The exact circuit depends on the module logging the code (OIC/CAB, PL3, or ECU).

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 8R / 8RT / 8RW Series Tractors (8245R to 8400R)
• 9RT Series Track Tractors (9470RT, 9520RT, 9570RT)
• STS Series Combines (9570 STS, 9670 STS, 9770 STS, 9870 STS)
• Self-Propelled Forage Harvesters (7180, 7280, 7380, 7480, 7580, 7780, 7980)
• Sugar Cane Harvesters (CH570, CH670)
• Tractors equipped with DirectDrive transmissions

1. 1

   Visually inspect all wiring harnesses and connectors leading to the affected control unit (Cab, Transmission, or Engine) for signs of chafing, melted insulation, loose connections, or corrosion

2. 2

   Ensure the ground connections for the module are secure and free of rust or corrosion, as a poor ground can cause erratic high current readings

3. 3

   Use a digital multimeter to measure the current at the supply lead to ensure it remains within the specified range for that circuit

4. 4

   Test the specific output circuit (e.g., ELX Output 1, transmission driver output, or injector hold circuit) for a short to ground

5. 5

   Verify if the control module software is up to date, as firmware updates can sometimes resolve current regulation anomalies

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable to prevent electrical spikes during testing.

2. 2

   Isolate the Circuit

   Disconnect the harness connector at the module logging the code (OIC, CAB, PL3, or ECU).

3. 3

   Pin Inspection

   Check the module pins and harness terminals for pushed-out pins, moisture intrusion, or green corrosion. Clean with electrical contact cleaner if necessary.

4. 4

   Trace the Short

   Using a multimeter set to ohms, check the affected output wire for continuity to ground. Trace the harness along the chassis/cab routing to locate any areas where the wire has rubbed against the frame.

5. 5

   Repair Wiring

   If a short is found, cut out the damaged section of wire, splice in a new section using OEM-approved crimp connectors, and seal with heat-shrink tubing.

6. 6

   Component Testing

   If the wiring is intact, test the component at the end of the circuit (e.g., a relay, transmission solenoid, or fuel injector). If the component has an internal short causing it to draw high amps, replace it.

7. 7

   Reassemble and Clear Codes

   Reconnect all harnesses and the battery. Turn the key on, clear the stored fault codes, and operate the machine to verify the code does not return. If the code immediately returns and all external wiring/components test good, the control module itself has likely failed internally and must be replaced.