Battery
Common no-start cause. Match size, terminal layout, and cold-cranking requirements.
Generac Error Code 1700 — Field Boost Fail Fix
What it means: The Evolution controller commanded field boost (applying battery voltage to the rotor winding for initial excitation) but the generator did not produce output voltage. The controller shuts down with error 1700.
The generator will crank and run but will not produce power. This is one of the most common Generac faults on units that have been sitting idle for extended periods.
Common Causes
| Cause | Frequency | Fix Difficulty |
|---|---|---|
| Tripped DPE (field boost) circuit breaker | High | Easy |
| Worn or stuck carbon brushes | Medium | Easy |
| High rotor resistance from corrosion | Medium | Moderate |
| Failed AVR (voltage regulator) | Medium | Moderate |
| Open rotor winding | Low | Hard (rewind or replace) |
| Slip ring surface corroded or grooved | Low | Moderate |
Step-by-Step Fix
1. Reset the DPE Breaker
The DPE (Dual Pole Energy) circuit breaker is a small 5A breaker on the control panel labeled “DPE” or “FIELD BOOST.” Push it firmly to reset — it should click. If it trips again immediately when starting, there’s a short in the rotor circuit or the brush holder.
2. Test Rotor Resistance
With the generator off and battery disconnected, locate the two brush wires in the brush holder (typically red and black). Disconnect them from the brush holder and measure resistance with a multimeter. A good rotor reads 18–35 ohms at room temperature. An open circuit (OL) means the rotor winding is burned open. A reading above 50 ohms suggests corrosion at the slip rings or partial winding damage.
3. Inspect Brushes and Slip Rings
Remove the brush holder (two screws on most Generac models). Check brush length against the wear line — brushes shorter than 3/8 inch need replacement. Inspect the slip rings on the rotor shaft — they should be smooth and shiny with no more than 1/32 inch groove depth. Clean with 400-grit silicon carbide paper if needed.
Generac brush holder assembly: part 0G5416 ($45). Brushes alone: 0G4685 ($15).
4. Test the AVR Output
With the generator running, measure AC voltage at the AVR output terminals (the two wires going to the rotor brush holder). You should see 10-20 VAC from the AVR during field boost. If the DPE breaker is good, rotor resistance is normal, but there’s no AVR output, the AVR needs replacement. Generac AVR 0F6004 (~$120) fits most Guardian units.
5. Clear the Code and Test
After repair: reset the DPE breaker, clear active alarms on the Evolution controller, and start the generator. Confirm it builds voltage by measuring at the main breaker. Voltage should stabilize at 120/240V within 10 seconds of starting.
Parts That May Need Replacement
| Part | Part Number | Cost | Where to Buy |
|---|---|---|---|
| Brush holder assembly | Generac 0G5416 | $40-$55 | Generac Parts |
| Carbon brushes (pair) | Generac 0G4685 | $12-$18 | Generac Parts |
| AVR / voltage regulator | Generac 0F6004 | $100-$140 | Generac Parts |
| AVR (alt part) | Generac 0G3947 | $150-$200 | Generac dealer |
| DPE breaker (5A) | Generac 0D4435 | $8-$15 | Generac Parts |
Technician Tips
Generac generator fault codes are displayed as flashing LED patterns on the controller. The red LED indicates a fault condition; green means normal operation. Code 1500 (low oil pressure) is the most common Generac fault — check oil level first, then the oil pressure switch. Generac generators have a built-in exercise cycle (every 7 days) — if the generator fails its exercise test, it logs a fault that may not trigger a warning light. Check the controller’s fault history to find these logged events.
Maintenance: Generac recommends oil changes every 100 hours of operation or annually. Skipping oil changes accelerates wear, sludge buildup, and low-oil shutdowns, so log each service interval and verify the controller maintenance timer after service.
Need Replacement Parts?
Before ordering, match the generator part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.