What is Hitachi ZW310-5A Fault Code 111701-6?

Fault Code 111701-6 on the Hitachi ZW310-5A wheel loader indicates a communication error with the transmission control unit (TCU), specifically a CAN bus data link failure between the engine ECM and transmission controller. This code triggers when the main electronic control module detects that transmission-related data packets are not being received or are incomplete for more than 2 seconds during operation.

This diagnostic trouble code is critical for the ZW310-5A because this model relies on integrated electronic control between the engine and ZH200 automatic transmission system. When communication fails, the machine cannot properly coordinate engine speed with gear selection, leading to performance protection modes that limit productivity and can potentially cause premature component wear if operated under fault conditions.

Common Symptoms

• Transmission warning light illuminated on the instrument cluster, often accompanied by a check engine light
• Machine enters limp mode, restricting operations to 2nd or 3rd gear only with no automatic shifting capability
• Erratic or delayed gear shifting, especially during load changes or when operating on inclines
• Intermittent loss of power or unexpected downshifting under normal operating loads
• Diagnostic display showing multiple cascade codes related to transmission functions (111XXX series)

Potential Causes

The most common technical causes for Code 111701-6 on used ZW310-5A machines include:

• CAN bus wiring harness damage between the engine compartment and transmission housing—particularly at the harness routing point near the left-side hydraulic tank where vibration causes insulation wear
• Corroded or loose 28-pin connector (C203) at the transmission control module, often caused by seal deterioration allowing moisture intrusion
• Failed transmission control unit itself, with capacitor degradation common in machines exceeding 8,000 operating hours
• ECM software version mismatch after engine controller replacement without proper TCU parameter updates
• Low system voltage (below 22V on 24V systems) causing communication dropout during high electrical load conditions
• Damaged CAN bus termination resistors (120-ohm) at either the ECM or TCU endpoints

How to Troubleshoot and Fix Code 111701-6

Step 1: Verify Communication Pathway Connect Hitachi Dr.EX diagnostic software to the machine's diagnostic port. Check for active communication with both the engine ECM and transmission TCU independently. If only one module responds, this isolates whether the fault is controller-specific or wiring-related. Use the software's CAN bus monitor function to observe data traffic in real-time.

Step 2: Inspect Physical Connections With the ignition off, inspect connector C203 at the transmission housing and connector C118 at the engine ECM. On used excavators, these connectors frequently show green corrosion on brass terminals. Disconnect each connector and measure pin-to-pin resistance on the CAN-High and CAN-Low wires (typically pins 16 and 24). You should read approximately 60 ohms with both modules connected (two 120-ohm resistors in parallel).

Step 3: Check Harness Integrity Physically trace the CAN bus harness from ECM to TCU, paying special attention to areas with metal contact or zip-tie compression points. Use a multimeter set to continuity mode and perform a wiggle test while monitoring resistance—any fluctuation indicates damaged wiring. For used machines, check the harness section near the steering column pivot point, a known wear location on the ZW310-5A.

Step 4: Voltage Supply Verification Measure voltage at the TCU power supply pin (pin 1 on C203) with the ignition on. Voltage should be stable at 24V ±1V. If voltage drops below 22V during cranking or under electrical load, investigate the charging system and battery condition before condemning electronic modules.

Step 5: Module Replacement Protocol If all wiring and connections test normally, the TCU may require replacement. Critical: When installing a replacement TCU on used equipment, the module must be programmed with machine-specific parameters using Dr.EX software, including transmission serial number, gear ratios, and torque converter specifications. Failure to program properly will result in recurring communication faults.

---

Disclaimer: This guide provides general troubleshooting information for Hitachi ZW310-5A fault code 111701-6. Hydraulic and electrical systems operate under high pressure and voltage. Always consult the official Hitachi service manual for your specific machine serial number and consider engaging a certified Hitachi technician for complex electrical diagnostics and CAN bus repairs.