What is Case CX220C Fault Code 1112?

Fault Code 1112 on the Case CX220C excavator indicates a Fuel Injection Pump Timing Actuator Circuit malfunction. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects an abnormal electrical signal or response from the fuel injection timing control system, specifically related to the timing actuator solenoid or its associated wiring.

The fuel injection timing actuator plays a critical role in optimizing combustion efficiency by precisely adjusting when fuel is injected into the cylinders based on engine load, speed, and temperature. On the CX220C's Isuzu engine platform, this system directly impacts fuel economy, power output, and emissions compliance. When Code 1112 is active, the ECM typically defaults to a fixed injection timing strategy, which can significantly reduce performance and increase fuel consumption on these used machines.

Common Symptoms

• Check Engine Light or malfunction indicator lamp illuminated on the instrument cluster
• Noticeable loss of engine power or reduced hydraulic response, especially under heavy load conditions
• Rough idle or irregular engine running, particularly during cold starts
• Black or gray exhaust smoke indicating incomplete combustion due to improper injection timing
• Increased fuel consumption as the ECM operates in limp-home mode with default timing parameters

Potential Causes

The most common causes of Code 1112 on used CX220C excavators include:

• Faulty fuel injection timing actuator solenoid due to internal coil failure or mechanical sticking (common after 5,000+ operating hours)
• Damaged wiring harness or corroded connectors between the ECM and timing actuator—check the harness routing near the fuel injection pump where vibration and heat cause insulation breakdown
• Poor electrical ground connection at the engine block or ECM mounting points, especially on machines operated in wet or corrosive environments
• ECM internal driver circuit failure, though less common, can occur on higher-hour machines
• Low system voltage from a failing alternator or weak batteries affecting solenoid operation

How to Troubleshoot and Fix Code 1112

Step 1: Visual Inspection Begin by inspecting the wiring harness from the ECM to the fuel injection pump timing actuator. On used excavators, pay special attention to harness routing near hot exhaust components and areas where cables contact the frame. Look for chafed insulation, corroded pin connectors, or oil contamination on the actuator connector.

Step 2: Electrical Testing Using a digital multimeter, disconnect the timing actuator connector and measure resistance across the solenoid terminals. Typical specification is 2-5 ohms (consult your service manual for exact values). Also check for continuity to ground—there should be infinite resistance. Measure supply voltage at the connector with ignition on; you should see battery voltage (12V+).

Step 3: Actuator Function Test If electrical values are correct, use Case diagnostic software (ServiceMaster or equivalent) to command the actuator on/off while monitoring response. A failed actuator will show no mechanical movement or clicking sound. For used machines, remove the actuator and inspect for carbon buildup or mechanical binding before replacement.

Step 4: Harness and Ground Verification Verify all engine ground straps are tight and corrosion-free. Check continuity of all wires between the ECM connector and actuator—resistance should be less than 0.5 ohms per wire.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Case service manual for your specific machine serial number and consult a qualified diesel technician for complex electrical diagnostics or ECM programming procedures.