What is Caterpillar Fault Code CID190?

Caterpillar fault code CID190 indicates a communication error with the Implement Pump Solenoid (IMP) circuit. This diagnostic trouble code (DTC) is logged when the Electronic Control Module (ECM) detects an open circuit, short circuit, or abnormal resistance in the wiring or solenoid controlling the implement pump's hydraulic flow.

The implement pump solenoid regulates hydraulic pressure and flow to auxiliary attachments like breakers, thumbs, and shears. On Caterpillar excavators, this circuit is critical for maintaining precise hydraulic control and preventing system overload. When CID190 appears, the ECM may reduce engine power or disable auxiliary hydraulic functions to protect the system from damage. For used excavators, this code often signals age-related wiring degradation or connector corrosion rather than catastrophic component failure.

Common Symptoms

When CID190 is active, operators typically experience:

• Malfunction indicator lamp (MIL) illuminated on the instrument cluster
• Loss of auxiliary hydraulic function or erratic attachment performance
• Intermittent power derate where engine RPM is limited to protect the hydraulic system
• Hydraulic pressure fluctuations during attachment operation
• Error message displayed on the monitor screen indicating solenoid circuit fault

Potential Causes

The most common technical reasons for CID190 on used Caterpillar excavators include:

• Damaged wiring harness due to rubbing against frame components or hydraulic lines (common wear point near the pump mounting area)
• Corroded or loose electrical connectors at the solenoid or ECM interface, especially on machines operating in wet or salty environments
• Failed implement pump solenoid due to internal coil breakdown or mechanical seizure
• Shorted pins in the ECM connector from moisture intrusion or physical damage
• Faulty ECM (rare, but possible after electrical surges or water damage in used machines)
• Broken or frayed wires inside protective loom covering, invisible without physical inspection

How to Troubleshoot and Fix Code CID190

Step 1: Visual Inspection Begin by thoroughly inspecting the wiring harness from the ECM to the implement pump solenoid. On used excavators, focus on areas where the harness passes near moving components, sharp edges, or heat sources. Check all electrical connectors for corrosion, bent pins, or moisture. Clean connectors with electrical contact cleaner and apply dielectric grease.

Step 2: Electrical Testing Using a digital multimeter, check the solenoid resistance. Disconnect the solenoid connector and measure resistance across the coil terminals—typical values range from 3-8 ohms (consult your service manual for exact specifications). Next, check for continuity in the wiring from the ECM connector to the solenoid. Resistance should be less than 5 ohms. Test for shorts to ground by measuring resistance between each wire and chassis ground (should read infinite/open circuit).

Step 3: Solenoid Function Test With the harness reconnected, use Caterpillar Electronic Technician (Cat ET) diagnostic software to command the solenoid on/off while monitoring voltage supply. You should see battery voltage (approximately 12-14V) at the solenoid when commanded on. If voltage is present but the solenoid doesn't click or actuate, replace the solenoid. If no voltage appears, trace back toward the ECM checking for open circuits or damaged relay components.

Step 4: Address Used Equipment Concerns For older excavators, remove protective loom covering and inspect for internal wire chafing that may not be visible externally. Check mounting brackets for the harness—loose or missing clips allow excessive movement and wire fatigue. Inspect the solenoid mounting area for hydraulic fluid leaks that may have contaminated electrical components.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Caterpillar service manual for your specific model and serial number. Complex electrical diagnostics should be performed by qualified technicians with proper training and calibrated equipment.