Case IH 3957 – Engine Control Unit (ECU): Injector 1 And/Or 4 Shorted To Low Source

The engine control system has detected a short circuit to ground (a "low source") in the electrical circuit controlling the fuel injectors for cylinder 1, cylinder 4, or both. This triggers an Amber warning lamp on the instrument cluster.

• skid steer
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• SR130
• SR160
• SR175
• SV185
• 410
• 420
• D33
• DX31
• DX33
• D35
• D45
• DX48
• Farmall 31
• Farmall 35
• Farmall 45
• Farmall 50
• Farmall 60

1. 1

   Visually inspect the wiring harness running from the Engine ECU to the fuel injectors (specifically cylinders 1 and 4) for damage, corrosion, abrasion, or incorrect attachment.

2. 2

   Disconnect the wiring harness from the ECU and test for continuity, specifically checking for a short to ground (low source) in the injector wiring.

3. 3

   If the wiring harness tests good, check the injectors themselves for internal electrical shorts.

1. 1

   Repair Wiring

   If the wiring harness test fails (a short to ground is found), locate the break or short in the damaged conductor and repair the wiring.

2. 2

   Replace Injector

   If the wiring harness is completely intact and tests good, the fault is likely an internal short within fuel injector 1 or 4. Replace the faulty injector(s).

3. 3

   Verify Repair

   Reconnect all harnesses. Operate the machine while monitoring the display.

4. 4

   Clear Codes

   If you do not find any further damage and the display indicates normal readings, use the Electronic Service Tool (EST) to erase the fault code and return the machine to operation.