Battery Charger Missing AC Input Signal
What does GENERAC-1517 mean?
The GENERAC-1517 (Generac Evolution) diesel fault code means: Battery Charger Missing AC Input Signal. This is a moderate severity code.
Common Symptoms
- Generator displays code 1517 on the Evolution controller panel
- Yellow or amber alarm LED is lit steady on the control panel
- Generator still starts and runs, but battery maintenance charging has stopped
- OnCue or Mobile Link app shows a 1517 alert or 'Charger Missing AC' warning
- Battery voltage slowly drops over days if the condition is not fixed
- Generator may eventually fail to crank during a power outage after extended time with no charging
- Weekly exercise cycle completes normally but the 1517 fault remains after shutdown
Probable Causes (Ranked by Likelihood)
- Utility AC power supply to the generator enclosure or transfer switch area is interrupted, cutting the charger's input Very Likely
- Wiring between the main board's AC input terminals and the battery trickle charger circuit is loose, corroded, or broken Likely
- Internal battery charger module on the controller board has failed and no longer reads AC presence Likely
- Main circuit breaker or dedicated breaker feeding the generator's 120V receptacle or charger circuit has tripped Possible
- Faulty or damaged Evolution controller board misreporting the AC input status Possible
- ATS wiring fault that inadvertently drops the utility feed to the charger input terminals during standby Less Likely
- Rodent damage or moisture intrusion in the conduit or harness carrying AC to the charger circuit Less Likely
Step-by-Step Diagnostic Procedure
Step 1. Put the generator panel switch to OFF. Check that utility power is present at your home's main panel and that no breakers supplying the generator's dedicated circuit are tripped. Reset any tripped breaker and then return the panel switch to AUTO to see if 1517 clears.
Step 2. Inspect the generator's exterior AC input connection point, usually a conduit knockout on the side of the enclosure. Look for obvious damage, corrosion, or a conduit that has pulled loose. A disconnected conduit means no AC is reaching the charger.
Step 3. With the generator in OFF and utility power confirmed on, use a multimeter set to AC voltage. Measure at the charger input terminals on the Evolution controller board (typically labeled L1 and N on the board's charger header). You should read approximately 120V AC. A reading of 0V confirms the AC feed is missing.
Step 4. Trace the wiring from the utility AC feed point to the controller board charger terminals. Look for loose ring terminals, pinched wires, burnt insulation, or corrosion at every connection point. Tug gently on each wire to check for hidden breaks.
Step 5. Check the in-line fuse or small circuit breaker on the charger input circuit if your model has one. On many Evolution-based units this is a 3A or 5A fuse on the control board itself. A blown fuse here will drop the charger AC input and set 1517.
Step 6. If wiring and fuses check out, measure battery voltage at the battery terminals with the generator in OFF. A fully charged 12V battery should read 12.6V or higher. A reading below 12.0V means the battery has already partially discharged and may need a separate charger while you finish diagnosing.
Step 7. If all external wiring is intact and power is confirmed at the board terminals but 1517 persists, the internal charger circuit on the Evolution controller board is the likely culprit. At this point the board needs evaluation or replacement by a qualified technician. This step requires specialty diagnostics beyond a standard multimeter.
Step 8. After any repair, return the panel to AUTO and use the Generac Mobile Link or the display panel's fault history scroll to confirm the 1517 code has cleared. If it has not cleared, press the OFF button and then AUTO again to reset the fault register.
Frequently Asked Questions
What does Generac code 1517 mean?
Code 1517 means the Evolution controller has detected that the battery trickle charger is not receiving utility AC power. The generator has a small built-in charger that keeps the starting battery topped off while the unit sits in standby. When that charger loses its AC feed, the battery slowly discharges on its own and eventually the generator may not be able to crank when the power goes out.
Can my generator still run with code 1517 active?
Yes, it can still start and produce power as long as the battery has enough charge to crank the engine. The code itself does not shut the generator down. However, if the battery keeps draining with no charging, you may eventually get a no-crank failure during a real outage. Treat this as a time-sensitive moderate fault and resolve it within a few days.
How much does it cost to fix code 1517?
If the fix is a tripped breaker or a loose wire, your cost is essentially zero. A replacement fuse on the controller board is under $10. If the battery has discharged enough to need replacement, budget $75-$150 for a new battery. A failed Evolution controller board is the worst-case scenario, running $300-$600 installed by a pro.
Will the generator start the next time the power goes out?
It depends on how long the 1517 condition has existed and how low the battery has dropped. If the code just appeared, you likely have days to weeks of cranking reserve. If the code has been active for weeks or the battery is already below 12V, there is a real risk the generator will not crank when you need it. Check battery voltage now and connect a standalone trickle charger to buy yourself time while you diagnose the root cause.