08-11-2025, 10:41 PM
Overview of the Problem
The Genie S-60 boom lift, particularly older models like the 1995 unit powered by a Deutz diesel engine, can exhibit a perplexing issue: the engine starts normally, but the voltmeter reads zero and all control functions remain disabled. Occasionally, pressing the start switch a second time causes the voltmeter to jump to 14 volts and restores full control functionality—including the high idle solenoid. However, this workaround becomes unreliable over time, leaving operators stranded with a running engine but no operational controls.
Understanding the Electrical System Architecture
To troubleshoot this issue, it’s essential to understand the Genie S-60’s electrical and control system. Key components include:
- Ignition start module
- Contact relays (notably CR2)
- Fuel shutoff solenoid
- Alternator and excitor circuit
- Voltage regulator
- Control switches (ground and basket)
- High idle solenoid
Terminology Note: Excitor Wire and Contact Relay
- Excitor Wire: A wire that supplies initial voltage to the alternator’s field coil, enabling it to begin charging.
- Contact Relay (CR2): An electromechanical switch that energizes multiple circuits, including the alternator, fuel solenoid, and control logic.
Symptoms and Diagnostic Clues
The most telling symptom is the zero reading on the voltmeter after startup, followed by a sudden jump to 14 volts when the start switch is pressed again. This behavior suggests that the alternator is not being excited properly during the initial start sequence. Without excitation, the alternator cannot begin charging, and the control system may interpret this as a fault, disabling functions.
Field Anecdote: The “Tap-to-Start” Trick
One operator discovered that holding the start switch for a fraction longer—just a millisecond—allowed the system to initialize correctly. This workaround, while clever, points to a deeper issue: inconsistent voltage delivery during startup. It’s reminiscent of a case from a Midwest rental yard where a Genie Z-45 exhibited similar symptoms. The culprit? A corroded excitor wire terminal that intermittently failed to deliver voltage during cranking.
Step-by-Step Diagnostic Strategy
1. Check the excitor wire at the alternator
– Use a multimeter or test light to verify voltage during and after startup
– If no voltage is present, trace the wire back to CR2 and the ignition module
2. Test the alternator manually
– Disconnect the excitor wire
– Start the engine and apply 12V directly to the excitor terminal
– If the alternator begins charging, the alternator is functional and the issue lies upstream
3. Inspect CR2 relay
– Confirm that the relay energizes during startup
– Check for continuity across the relay terminals
– Replace if contacts are worn or coil is weak
4. Evaluate the ignition start module
– This module sends the signal to energize CR2
– If faulty, it may fail to trigger the relay consistently
5. Verify fuel shutoff solenoid operation
– If the engine runs and shuts off correctly, CR2 is likely functioning
– However, partial failure of CR2 could still affect other circuits
Suggested Parameters for Healthy Operation
- Excitor wire voltage during startup: ≥12V
- Alternator output voltage: 13.8–14.2V at idle
- CR2 coil resistance: 60–120 ohms
- Battery voltage during cranking: ≥10.5V
Common Causes of High Idle and Control Failures
- Weak or corroded excitor wire connection
- Failing CR2 relay with intermittent contact
- Voltage drop during cranking due to weak battery or poor ground
- Faulty ignition start module
- Alternator internal fault (e.g., bad diode or regulator)
- Control switch wear or misalignment
Recommendations for Repair and Prevention
- Replace CR2 relay with OEM or high-quality aftermarket unit
- Clean and tighten all excitor wire terminals
- Test battery under load and replace if voltage drops below threshold
- Inspect alternator belt tension and pulley alignment
- Use dielectric grease on electrical connectors to prevent corrosion
- Document voltage readings and relay behavior for future reference
Anecdote: The “Ghost Voltage” Mystery
In a similar case involving a Genie S-65, technicians chased a phantom voltage issue for weeks. The voltmeter would spike randomly, and controls would fail mid-operation. Eventually, they discovered a cracked alternator housing that allowed moisture to short the excitor terminal intermittently. The lesson? Never underestimate the impact of environmental wear on electrical components.
Alternative Solutions and Upgrades
- Install a manual alternator excitation switch for diagnostic use
- Upgrade to a self-exciting alternator with built-in regulator
- Replace aging control switches with sealed, weather-resistant models
- Add a startup delay module to ensure stable voltage before control activation
Conclusion: Precision Matters in Electrical Diagnostics
The Genie S-60’s high idle and control issues stem from a delicate interplay between voltage delivery, relay timing, and alternator excitation. While the machine may start and run, the absence of proper charging voltage can disable critical functions. By methodically testing each component—from the excitor wire to the ignition module—technicians can restore reliable operation and avoid the frustration of intermittent failures. In the world of aerial lifts, a few volts can make the difference between a productive day and a dead machine.
The Genie S-60 boom lift, particularly older models like the 1995 unit powered by a Deutz diesel engine, can exhibit a perplexing issue: the engine starts normally, but the voltmeter reads zero and all control functions remain disabled. Occasionally, pressing the start switch a second time causes the voltmeter to jump to 14 volts and restores full control functionality—including the high idle solenoid. However, this workaround becomes unreliable over time, leaving operators stranded with a running engine but no operational controls.
Understanding the Electrical System Architecture
To troubleshoot this issue, it’s essential to understand the Genie S-60’s electrical and control system. Key components include:
- Ignition start module
- Contact relays (notably CR2)
- Fuel shutoff solenoid
- Alternator and excitor circuit
- Voltage regulator
- Control switches (ground and basket)
- High idle solenoid
Terminology Note: Excitor Wire and Contact Relay
- Excitor Wire: A wire that supplies initial voltage to the alternator’s field coil, enabling it to begin charging.
- Contact Relay (CR2): An electromechanical switch that energizes multiple circuits, including the alternator, fuel solenoid, and control logic.
Symptoms and Diagnostic Clues
The most telling symptom is the zero reading on the voltmeter after startup, followed by a sudden jump to 14 volts when the start switch is pressed again. This behavior suggests that the alternator is not being excited properly during the initial start sequence. Without excitation, the alternator cannot begin charging, and the control system may interpret this as a fault, disabling functions.
Field Anecdote: The “Tap-to-Start” Trick
One operator discovered that holding the start switch for a fraction longer—just a millisecond—allowed the system to initialize correctly. This workaround, while clever, points to a deeper issue: inconsistent voltage delivery during startup. It’s reminiscent of a case from a Midwest rental yard where a Genie Z-45 exhibited similar symptoms. The culprit? A corroded excitor wire terminal that intermittently failed to deliver voltage during cranking.
Step-by-Step Diagnostic Strategy
1. Check the excitor wire at the alternator
– Use a multimeter or test light to verify voltage during and after startup
– If no voltage is present, trace the wire back to CR2 and the ignition module
2. Test the alternator manually
– Disconnect the excitor wire
– Start the engine and apply 12V directly to the excitor terminal
– If the alternator begins charging, the alternator is functional and the issue lies upstream
3. Inspect CR2 relay
– Confirm that the relay energizes during startup
– Check for continuity across the relay terminals
– Replace if contacts are worn or coil is weak
4. Evaluate the ignition start module
– This module sends the signal to energize CR2
– If faulty, it may fail to trigger the relay consistently
5. Verify fuel shutoff solenoid operation
– If the engine runs and shuts off correctly, CR2 is likely functioning
– However, partial failure of CR2 could still affect other circuits
Suggested Parameters for Healthy Operation
- Excitor wire voltage during startup: ≥12V
- Alternator output voltage: 13.8–14.2V at idle
- CR2 coil resistance: 60–120 ohms
- Battery voltage during cranking: ≥10.5V
Common Causes of High Idle and Control Failures
- Weak or corroded excitor wire connection
- Failing CR2 relay with intermittent contact
- Voltage drop during cranking due to weak battery or poor ground
- Faulty ignition start module
- Alternator internal fault (e.g., bad diode or regulator)
- Control switch wear or misalignment
Recommendations for Repair and Prevention
- Replace CR2 relay with OEM or high-quality aftermarket unit
- Clean and tighten all excitor wire terminals
- Test battery under load and replace if voltage drops below threshold
- Inspect alternator belt tension and pulley alignment
- Use dielectric grease on electrical connectors to prevent corrosion
- Document voltage readings and relay behavior for future reference
Anecdote: The “Ghost Voltage” Mystery
In a similar case involving a Genie S-65, technicians chased a phantom voltage issue for weeks. The voltmeter would spike randomly, and controls would fail mid-operation. Eventually, they discovered a cracked alternator housing that allowed moisture to short the excitor terminal intermittently. The lesson? Never underestimate the impact of environmental wear on electrical components.
Alternative Solutions and Upgrades
- Install a manual alternator excitation switch for diagnostic use
- Upgrade to a self-exciting alternator with built-in regulator
- Replace aging control switches with sealed, weather-resistant models
- Add a startup delay module to ensure stable voltage before control activation
Conclusion: Precision Matters in Electrical Diagnostics
The Genie S-60’s high idle and control issues stem from a delicate interplay between voltage delivery, relay timing, and alternator excitation. While the machine may start and run, the absence of proper charging voltage can disable critical functions. By methodically testing each component—from the excitor wire to the ignition module—technicians can restore reliable operation and avoid the frustration of intermittent failures. In the world of aerial lifts, a few volts can make the difference between a productive day and a dead machine.
