Bobcat 773 Starting Problems and Diagnostic Insights

[MikePhua]

The Bobcat 773 skid‑steer loader is one of the most widely used compact machines in construction, landscaping, agriculture, and rental fleets. Known for its durability and versatility, the 773 series—especially the G‑Series Turbo High‑Flow variant—remains popular decades after its release. However, like all electronically controlled equipment, it can experience starting issues that confuse operators. This article examines a real‑world case involving a 773 that refused to start and displayed error code 34‑04, expanding the discussion with technical explanations, troubleshooting strategies, and industry context.

The Bobcat 773 and Its Development Background
The Bobcat 700‑series was introduced during a period when compact loaders were rapidly gaining global market share. The 773 became one of the company’s best‑selling models due to:

• A balanced operating weight of roughly 5,800–6,000 lbs
  
• A rated operating capacity around 1,700 lbs
  
• A reliable Kubota V2203 diesel engine
  
• Optional High‑Flow hydraulics for demanding attachments
  
• A G‑Series upgrade that introduced improved electronics and operator comfort
  

Bobcat, founded in the 1950s in North Dakota, grew into one of the world’s most recognized compact equipment manufacturers. By the early 2000s, annual global sales of skid‑steers exceeded 70,000 units, with Bobcat consistently holding a leading market share.
The 773’s longevity means many units remain in service today, making troubleshooting knowledge especially valuable.

Understanding the Error Code 34‑04
The reported issue involved:

• The machine refusing to start
  
• Indicator lights flashing three times
  
• Display showing error code 34‑04
  
• A new battery already installed
  
• All fuses and cables checked
  

Terminology

• Error Code 34‑04 
  A diagnostic code indicating a battery voltage error or voltage out of expected range.
  
• Voltage Out of Range 
  The control system detects either too low or too high voltage, preventing startup to protect electronic components.
  
• Ground Fault 
  A poor connection between the electrical system and chassis ground, often causing intermittent or false voltage readings.
  

Even though the battery was new, the system still detected abnormal voltage, suggesting the issue was not the battery itself but something upstream or downstream in the electrical circuit.

Why a New Battery Does Not Guarantee Proper Voltage
A common misconception is that installing a new battery eliminates electrical problems. In reality, several factors can still cause voltage‑related errors:

• Loose or corroded ground straps
  
• Damaged battery cables
  
• Internal corrosion inside cable lugs
  
• Faulty ignition switch
  
• Weak alternator output
  
• Poor connections at the control panel
  
• Voltage drop under load due to hidden resistance
  

In the retrieved case, the operator confirmed that all grounds and terminals were checked, but intermittent voltage issues can be subtle and require deeper inspection.

Diagnostic Strategy for Bobcat 773 Starting Failures
A structured approach helps isolate the cause of voltage‑related no‑start conditions.
Step 1: Verify Battery Health Under Load

• A battery may show 12.6V at rest but drop below 9V during cranking
  
• Load testing reveals hidden weaknesses
  

Step 2: Inspect All Grounds Thoroughly

• Frame‑to‑engine ground strap
  
• Battery‑to‑frame ground
  
• Control module ground point
  

Even a slightly loose ground can trigger code 34‑04.
Step 3: Check the Main Power Relay and Fuse Block

• Corrosion inside the fuse block can cause intermittent voltage loss
  
• Relays may click but fail to pass sufficient current
  

Step 4: Measure Voltage at the Control Panel

• The panel lights flashing three times indicates the controller is losing power
  
• Voltage drop between battery and panel must be measured directly
  

Step 5: Inspect the Key Switch

• Worn contacts can cause sudden voltage interruption
  
• Many 773 owners report key switch failures after 10–15 years
  

Step 6: Confirm Alternator Output

• If the alternator is weak, the machine may start once but fail later
  
• Low charging voltage can confuse the controller
  

A Real‑World Story: When a New Battery Wasn’t the Cure
A contractor in Arizona experienced a similar issue with his 773. After replacing the battery twice, the machine still refused to start. A technician eventually discovered that the ground strap had corroded internally beneath the insulation. The strap looked clean from the outside but had nearly disintegrated inside. Replacing the strap immediately resolved the issue.
This story illustrates how electrical problems often hide in places that appear visually normal.

Why the Control Panel Shuts Down After Three Flashes
The three‑flash sequence is a protective behavior:

• The controller attempts to initialize
  
• It detects unstable voltage
  
• It shuts down to prevent damage
  

This is common in G‑Series Bobcats, which rely heavily on stable voltage for safety interlocks, hydraulic lockouts, and engine management.

Additional Factors That Can Trigger Voltage Errors
Environmental Conditions

• Moisture intrusion
  
• Temperature‑related expansion and contraction
  
• Vibration loosening connectors
  

Aging Components

• Wiring harness fatigue
  
• Oxidation on terminals
  
• Brittle insulation
  

Operator Modifications

• Aftermarket lights
  
• Auxiliary electrical accessories
  
• Poorly installed radios or alarms
  

These can overload circuits or introduce electrical noise.

Recommended Solutions and Preventive Measures
Short‑Term Fixes

• Clean all grounds with a wire brush
  
• Apply dielectric grease to terminals
  
• Tighten battery cables beyond finger‑tight
  

Long‑Term Improvements

• Replace old ground straps with braided copper straps
  
• Install a battery disconnect switch to reduce corrosion
  
• Replace the ignition switch if contacts feel loose
  
• Inspect the wiring harness annually
  

Professional Diagnostic Tools

• Voltage drop testing
  
• Load testing
  
• Oscilloscope analysis for intermittent faults
  

Conclusion
The Bobcat 773 remains a highly respected and widely used skid‑steer loader, but its electronically controlled G‑Series models depend heavily on stable electrical voltage. Error code 34‑04, even with a new battery installed, often points to deeper issues such as poor grounding, hidden corrosion, or voltage drop in the wiring harness. By understanding the machine’s electrical architecture and applying systematic troubleshooting, operators can resolve starting problems efficiently and keep these durable machines working for years to come.