Hyundai R805LC-7 Fault Code 167-1: Meaning and Fix Guide

What is Hyundai R805LC-7 Fault Code 167-1?

Fault Code 167-1 indicates a low voltage or open circuit condition in the Boom Priority Control Solenoid Valve circuit. This code is triggered when the Electronic Control Module (ECM) detects abnormal electrical resistance or insufficient voltage supply to the boom priority solenoid, which regulates hydraulic flow priority to the boom during combined operations.

This fault is critical for the R805LC-7's hydraulic performance because the boom priority system ensures adequate hydraulic power reaches the boom cylinder even when multiple functions operate simultaneously. When this circuit malfunctions, operators may experience reduced boom performance and compromised productivity on demanding excavation tasks.

Common Symptoms

When Code 167-1 is active on your Hyundai R805LC-7, you may notice:

• Slow or sluggish boom response, especially during combined operations (boom + swing or boom + stick)
• Intermittent boom function loss when other hydraulic functions are engaged
• Warning indicator illuminated on the instrument cluster display
• Reduced digging force compared to normal operating conditions
• Inconsistent hydraulic performance that worsens as the machine warms up

Potential Causes

The most common technical reasons for Code 167-1 on used R805LC-7 excavators include:

• Damaged solenoid wiring harness from abrasion against the boom cylinder or frame (known wear point on this model)
• Corroded electrical connectors at the solenoid valve due to moisture intrusion through deteriorated seals
• Failed boom priority solenoid valve with internal coil breakdown or mechanical sticking
• Broken or frayed wires within the main harness near the ECM connection points
• Poor ground connection at the hydraulic valve mounting location
• ECM internal fault (rare, but possible on high-hour used machines)

How to Troubleshoot and Fix Code 167-1

Step 1: Visual Inspection Begin by inspecting the boom priority solenoid valve connector located on the main control valve. Check for corrosion, bent pins, or moisture. On used excavators, carefully trace the wiring harness along the boom cylinder path—this is a common rub point where insulation wears through.

Step 2: Electrical Testing Using a digital multimeter, disconnect the solenoid connector and measure resistance across the solenoid terminals. You should read approximately 10-15 ohms (consult service manual for exact spec). Next, check for 12-24V supply voltage (key on, engine off) at the harness side connector. Verify ground continuity is less than 1 ohm.

Step 3: Component Testing If voltage and ground are correct but resistance is out of range, replace the boom priority solenoid valve. Before installation on used machines, apply dielectric grease to connector pins to prevent future corrosion. If all electrical values are correct, perform an ECM output test using Hyundai diagnostic software (Hi-MATE or equivalent) to verify the controller can properly energize the circuit.

Step 4: Harness Repair For damaged wiring, repair using proper gauge wire (typically 18-20 AWG) with heat-shrink solder connectors. Reroute harness away from moving components and secure with vibration-resistant clamps.

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Disclaimer: This guide provides general troubleshooting information. Always consult the manufacturer's service manual and consider professional diagnostic assistance for complex electrical issues, especially on high-voltage systems.