Case IH 3135 – Engine Control Unit (ENG / EDC): Cold Start Lamp _Short circuit to Ground

The engine controller has detected a 'Short circuit to Ground' on the Cold Start Lamp circuit, meaning the voltage is lower than expected. This is typically caused by chafed wiring touching the machine's chassis or an internally shorted lamp/LED.

• Case IH Magnum 235 - 340 (Series 4)
• Case IH Steiger series
• Case IH Farmall series (95U, 105U, 115U Pro)
• Case IH CVX series (140, 150, 160, 175, 195)

1. 1

   Inspect the wiring harness running from the Engine Control Unit (EDC) to the cab/instrument cluster for pinched wires, rubbed-through insulation, or areas resting against the metal chassis.

2. 2

   Disconnect the harness at the EDC and instrument cluster, and use a multimeter to measure resistance between the Cold Start Lamp signal wire and a known good chassis ground to check for continuity.

3. 3

   If the wiring tests good (open to ground when disconnected), check the cold start lamp bulb or the instrument cluster itself for an internal short circuit.

4. 4

   Inspect the EDC and cab bulkhead connectors for moisture, corrosion, or bent pins that could bridge the lamp circuit to a ground pin.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery terminal to prevent electrical spikes.

2. 2

   Isolate the Short

   Based on the multimeter tests, locate the exact point of the short. If the short is in the wiring harness, carefully open the wire loom at the damaged section.

3. 3

   Repair the Wiring

   Cut out the damaged section of the wire. Splice in a new section of wire using OEM-approved weather-sealed heat-shrink butt connectors. Wrap the repaired section in high-temperature harness tape and secure it in a protective loom away from sharp metal edges.

4. 4

   Replace the Lamp (if applicable)

   If the short was isolated to the bulb itself, remove the instrument cluster bezel, extract the faulty cold start bulb, and install a replacement. (Note: On many modern Tier 4a displays, the LED is integrated into the cluster circuit board. If the cluster board is internally shorted, the cluster may require replacement or specialized repair).

5. 5

   Reassembly and Clearing

   Reconnect all harnesses and the battery. Turn the key to the ON position to verify the Cold Start Lamp illuminates and turns off correctly. Use a diagnostic scan tool to clear the inactive 3135 fault code from the EDC.