What is John Deere E240LC Fault Code 001638.16?

Fault Code 001638.16 on the John Deere E240LC excavator indicates an Auxiliary Hydraulic Pressure Sensor Circuit Voltage Below Normal, specifically a low voltage condition detected in the auxiliary hydraulic pressure sensor circuit. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects voltage readings below the manufacturer's specified threshold, typically under 0.5 volts, in the sensor circuit that monitors auxiliary hydraulic system pressure.

This fault is critical for the E240LC's performance because the auxiliary hydraulic system powers attachments like breakers, grapples, and augers. When the ECM cannot accurately read pressure data due to low voltage, it may limit auxiliary hydraulic functions or prevent proper attachment operation, directly impacting job site productivity and potentially causing unsafe operating conditions.

Common Symptoms

When fault code 001638.16 is active on your John Deere E240LC, operators typically experience:

• Auxiliary hydraulic functions become inoperative or intermittent, preventing proper attachment operation
• Amber warning light illuminated on the instrument cluster with fault code displayed
• Reduced hydraulic flow to auxiliary circuits, causing sluggish attachment performance
• ECM derate mode may activate in some cases, limiting engine RPM to protect the hydraulic system
• Attachment control functions may not respond to joystick inputs or exhibit erratic behavior

Potential Causes

The most common technical reasons for this fault code appearing on used E240LC excavators include:

• Damaged or corroded wiring harness connections at the auxiliary pressure sensor, particularly where harnesses route near moving components or the boom cylinder
• Failed auxiliary hydraulic pressure sensor due to internal electrical failure or contamination exposure
• Chafed or pinched sensor wiring at known rub points near the auxiliary valve bank mounting area
• Corroded connector pins at the sensor plug or ECM interface from water intrusion or age-related degradation
• Low supply voltage from the ECM to the sensor circuit caused by poor ground connections or ECM issues
• Open circuit in the sensor signal wire between the sensor and ECM

How to Troubleshoot and Fix Code 001638.16

Step 1: Visual Inspection Begin by locating the auxiliary hydraulic pressure sensor on the auxiliary valve block. Thoroughly inspect the wiring harness from the sensor to the ECM, paying special attention to areas where the harness contacts metal surfaces or moving components. On used excavators, check for harness wear, insulation damage, or signs of previous repairs. Examine the sensor connector for corrosion, bent pins, or moisture intrusion.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor connector and check for supply voltage at the harness side (should read approximately 5 volts with key on). Test ground continuity between the sensor ground pin and chassis ground (should read less than 1 ohm). Measure resistance of the sensor signal wire back to the ECM (typically 100-200 ohms depending on wire length).

Step 3: Sensor Testing and Replacement With the sensor connected, use John Deere Service Advisor diagnostic software or a compatible scanner to monitor live sensor voltage while the engine runs. Normal readings should range between 0.5-4.5 volts depending on system pressure. If voltage remains below 0.5 volts with proper supply voltage confirmed, replace the auxiliary pressure sensor. For used machines, always apply dielectric grease to connector pins during reassembly to prevent future corrosion issues.

Disclaimer: This guide provides general troubleshooting information. Always consult the official John Deere service manual for your specific machine serial number and consider professional diagnostic assistance for complex electrical issues or if you're unfamiliar with hydraulic system safety procedures.