What is Doosan DX150LC-9C Fault Code E000736-12?

Fault Code E000736-12 indicates a CAN communication error between the Engine Control Module (ECM) and the Monitor Control Module (MCM) on the Doosan DX150LC-9C excavator. This code specifically signals that the ECM has detected a loss of communication or intermittent signal disruption on the CAN bus network, which is the primary digital communication highway between the engine controller and the machine's monitoring systems.

This fault is critical because the CAN bus coordinates essential data sharing between control modules, including engine performance parameters, hydraulic system status, and operator display functions. When communication fails, the excavator's integrated systems cannot properly coordinate, potentially leading to reduced machine performance, inaccurate instrument readings, or even automatic engine derate modes to protect the equipment. On used excavators like the DX150LC-9C, this code often emerges due to age-related wiring degradation or connector corrosion rather than actual module failure.

Common Symptoms

• Erratic or blank monitor display showing incorrect engine RPM, coolant temperature, or fuel level readings
• Multiple warning lights illuminating simultaneously on the instrument cluster without clear cause
• Intermittent engine derate or reduced power output as the ECM enters failsafe mode
• Loss of diagnostic capability where the machine cannot properly communicate with service tools
• Flickering dashboard or complete instrument panel blackout during operation

Potential Causes

The most common technical causes for Code E000736-12 on used Doosan DX150LC-9C excavators include:

• Corroded or damaged CAN bus connectors at the ECM or MCM connection points, especially where harnesses pass through the engine bay bulkhead
• Frayed or pinched CAN communication wiring along known rub points near the battery box or beneath the operator cab mounting brackets
• Failed terminating resistors on the CAN network (typically 120-ohm resistors at network endpoints)
• Water intrusion into sealed connectors due to degraded weather seals on aging machines
• Voltage supply issues to either the ECM or MCM causing communication dropout
• ECM or MCM internal failure (less common, but possible on higher-hour machines)

How to Troubleshoot and Fix Code E000736-12

Step 1: Visual Inspection of Harnesses and Connectors Begin by inspecting all CAN bus wiring harnesses between the ECM (located near the engine) and the MCM (behind the instrument panel). Look specifically for chafing points where harnesses contact metal frames, especially near the cab pivot area on the DX150LC-9C. Check all connector pins for corrosion, bent pins, or moisture. On used excavators, these connectors often show green corrosion due to years of exposure—clean with electrical contact cleaner and dielectric grease.

Step 2: Test CAN Bus Continuity and Resistance Using a digital multimeter, disconnect both the ECM and MCM connectors. Measure resistance between CAN-High and CAN-Low terminals—you should read approximately 60 ohms with both terminating resistors in place. Check continuity of each individual CAN wire from ECM to MCM; infinite resistance indicates a break. Also verify there's no short to ground on either CAN line (should read infinite resistance to chassis ground).

Step 3: Verify Power Supply and Ground Circuits Check that both modules receive proper battery voltage (12-14V engine off, 13.5-14.5V running) at their power supply pins. Equally important, verify ground connections are clean and tight—poor grounds are frequent culprits on older machines. Test ground circuits for less than 0.5 ohms resistance to chassis ground.

Step 4: Advanced Diagnostics with Doosan Software Connect Doosan DMS (Diagnostic Master System) or equivalent diagnostic software. Monitor live CAN bus traffic to identify whether communication dropouts are intermittent or constant. The software can also verify if terminating resistors are functioning and whether message frames are being corrupted. For used excavators, perform a "wiggle test" by gently moving harnesses while monitoring communication—this often reveals intermittent failures from broken wire strands inside insulation.

Step 5: Component Replacement Priority If diagnostics point to hardware failure, replace components in this order: 1) Damaged harnesses or connectors first (most common), 2) Terminating resistors if measured values are incorrect, 3) MCM (less expensive module), 4) ECM only after all other possibilities are exhausted. Always clear codes and test operation after each repair.

---

Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Doosan service manual for your specific serial number, and consider professional diagnostic assistance for complex electrical issues. Improper repairs to CAN bus systems can cause additional control module damage.