701

Common Causes

• Actual low coolant level in tank due to normal evaporation, leakage, or coolant being carried out with chips and parts
• Coolant level float switch stuck in the down position due to chips, debris, or sludge buildup preventing float movement
• Broken or disconnected float switch linkage or mounting bracket causing switch to remain in low level state
• Wiring fault between coolant level switch and IOCON board input creating false low level signal
• IOCON board input failure on coolant level circuit causing incorrect reading even when tank is full

Troubleshooting Steps

1. 1Step 1: Visually inspect coolant tank and verify actual fluid level, add premixed coolant to proper fill line if genuinely low
2. 2Step 2: Access Diagnostics INPUTS page and observe coolant level switch input state while manually lifting float switch to verify proper signal change
3. 3Step 3: Remove chips and debris from around float switch mechanism and verify float moves freely up and down without binding
4. 4Step 4: With power off, disconnect coolant level switch connector and test switch continuity with float in up position (should be closed) and down position (should be open)
5. 5Step 5: Inspect wiring harness from level switch to IOCON connector for damaged insulation, broken wires, or corroded terminals especially in areas exposed to coolant spray
6. 6Step 6: Replace coolant level float switch with Haas OEM part if switch mechanism is damaged or contacts are failed, verify proper operation in diagnostics before returning to service