## What is Kobelco SK135SR-2 Fault Code B062?

**Fault Code B062 on the Kobelco SK135SR-2 excavator indicates a malfunction in the Auto-Idle Cancel Switch Circuit, specifically detecting an abnormal voltage signal or open/short circuit condition in the auto-idle switch system.** This code is triggered when the **Electronic Control Module (ECM)** detects that the auto-idle cancel switch is sending improper voltage signals or the circuit has failed completely.

The auto-idle function is critical for fuel efficiency and engine longevity on this model. When functioning correctly, it automatically reduces **engine RPM** during periods of inactivity, reducing fuel consumption and unnecessary wear. A fault in this circuit prevents the system from operating properly, potentially leading to increased fuel costs and preventing the operator from manually overriding the auto-idle feature when full power is needed immediately.

## Common Symptoms

When fault code B062 is active on your SK135SR-2, you may experience:

- **Warning light** illuminated on the instrument panel (typically amber/yellow)
- Auto-idle function fails to activate during idle periods, keeping engine at higher RPM continuously
- Inability to cancel auto-idle mode when attempting to use the cancel switch
- **Engine RPM** does not respond to auto-idle switch inputs
- Increased fuel consumption due to engine running at higher idle speeds constantly

## Potential Causes

The most common technical causes for B062 on used Kobelco SK135SR-2 excavators include:

- **Faulty auto-idle cancel switch** due to internal contact wear or moisture intrusion (extremely common on machines with 5,000+ hours)
- **Damaged wiring harness** between the switch and ECM, particularly at known rub points near the cab mounting brackets
- **Corroded or loose electrical connectors** at the switch or ECM interface—check connector C-34 specifically
- **Short circuit to ground** in the switch circuit wiring, often caused by harness chafing against metal surfaces
- **ECM internal fault** (rare, but possible on older used machines with electrical history)
- Broken or frayed wires inside the cab floor harness routing area

## How to Troubleshoot and Fix Code B062

**Step 1: Visual Inspection**
Begin by locating the auto-idle cancel switch (typically mounted on the right-hand console or armrest). Inspect all visible **wiring harness** sections for obvious damage, abrasion, or connector corrosion. On used excavators, pay special attention to harness routing near the cab pivot points where friction wear commonly occurs.

**Step 2: Test the Switch**
Disconnect the auto-idle cancel switch connector. Using a **digital multimeter**, check for continuity across the switch terminals while activating the switch. The switch should show **closed circuit (0 ohms)** when pressed and **open circuit (infinite resistance)** when released. Replace the switch if readings are inconsistent or if you detect internal resistance above 5 ohms.

**Step 3: Circuit Voltage Testing**
With the ignition on and switch disconnected, measure **voltage supply** at the harness connector. You should read approximately **12-14 volts DC** on the power supply wire (consult your SK135SR-2 service manual for specific pin identification). If no voltage is present, trace the circuit back toward the **ECM** checking for breaks or shorts.

**Step 4: Check Ground and Signal Return**
Verify the **ground circuit** has less than 0.5 ohms resistance to chassis ground. Test the signal wire for shorts to ground or power using resistance measurements with the **ECM connector** disconnected. On used machines, remove and clean all connector pins with electrical contact cleaner, as corrosion buildup is a primary failure point.

**Step 5: ECM Verification**
If all external components test correctly, the fault may lie within the **ECM input circuitry**. Before replacing the ECM, ensure all software updates have been applied using **Kobelco diagnostic software**. Clear the code, operate the machine, and verify if B062 returns.

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**Disclaimer:** This guide provides general diagnostic information for experienced technicians. Always consult the official Kobelco SK135SR-2 service manual for complete specifications and safety procedures. If you're uncomfortable performing electrical diagnostics, contact a certified Kobelco dealer or qualified heavy equipment technician.