JLG 600AJ No Power at Ground Control Console (ADE System Diagnostic)

Symptoms

• Ground control display is blank/dead
• Key switch has no effect in either platform or ground position
• No clicking from main start/ignition relays when keyswitch toggled
• Complete lack of function response from both ground and platform controls

Possible Causes

• Tripped or defective 15A/20A control system circuit breaker in the ground control box
• Blown 125A inline main power midi-fuse at the battery positive terminal box
• Corroded or broken wiring harness pins on the back of the ground control key switch
• Defective main power relay (Master Power Relay) or damaged Ground Control Module (GCM)

Diagnostic Procedure

1. 1
   Verify Battery State of Charge and Main Fuse

   Measure battery voltage directly across the terminals with a digital multimeter (should be >12.4V DC). Inspect the 125A midi-fuse located near the positive battery post or master disconnect switch for continuity.
2. 2
   Inspect Ground Control Box Circuit Breakers

   Locate the push-button thermal circuit breakers inside or on the side of the ground control box. Measure voltage on both terminals of each breaker with the key switch ON. If voltage is present on the supply terminal but not the load terminal, cycle the breaker or replace if failed.
3. 3
   Test Key Switch Outputs

   Access the rear of the Ground Control Module (GCM) key switch. Measure voltage at the input terminal (Constant 12V from battery) and verify output voltage on the 'Ground' circuit and 'Platform' circuit when switched to the respective positions.
4. 4
   Perform Voltage Drop Test on Ground Circuits

   Measure resistance/voltage drop between the GCM main ground pin (Terminal B on some harnesses) and the chassis ground point. Resistance must be less than 0.5 Ohms.

Common Repairs

• Replacement of defective key switch assembly
• Replacing the 125A inline midi-fuse or the 15A control system circuit breaker
• Cleaning and re-pinning corroded Deutsch connectors on the back of the ground box

Safety Precautions

• Chock wheels and ensure the platform is fully lowered and stowed
• Disconnect battery negative cable before servicing high-current fuses or relays
• Verify no hazardous energy is stored in the system

Required Tools

• Digital Multimeter (DMM)
• Deutsch Connector Pin De-pinning Tool
• Wire Strippers and Crimpers
• Basic Hand Tools (Sockets, Screwdrivers)

Related Fault Codes

People Also Ask

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• What voltage should be present at the JLG handheld analyzer plug when the system is dead?

Related Guides

Suggested Follow-Up Guides

• JLG 600AJ ADE Module Replacement and Software Programming Guide
• Troubleshooting JLG CAN-Bus Serial Communication Failures
• Step-by-Step JLG Ground Control Key Switch Circuit Testing
• JLG 600AJ Emergency Stop (E-Stop) Switch Circuit Bypass & Diagnostic Practice
• Testing and Rebuilding the Main Power Distribution Box on JLG Boom Lifts

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