Onan HGJAA-HGJAF error code 27 (Voltage Sense Lost)
Controller unable to sense output voltage (sense lead open, blown sense fuse, or field collapse). Manual logic: no sense voltage (0 VAC across S1-S2) for 1 continuous second after start disconnect.
What to check, and in what order, is in the app. The flow Onan Code 27 — Voltage Sense Fault walks this code step by step with the pass/fail measurements, wiring schematics and procedures that go with it, and it works offline in the bay.
Start free trial 14 days free, no card neededDocumented in
- Cummins-Onan Service Manual (document 0983-0501 Issue 26, March 2018, 202 pp) covering HGJAA Spec A-E / HGJAB A-E / HGJAC A-C / HGJAD A-E / HGJAE A-E / HGJAF A-C (rv-tech-resources/25-onan-hgjaa/0983-0501_Onan_HGJAA-HGJAF_Service_Manual_Issue_26.pdf)
- Onan HGJAA Generator Technician Service Diagnostic Reference (rv-tech-resources/25-onan-hgjaa/Onan_HGJAA_Generator_Technician_Service_Diagnostic_Reference.md)
Related codes
- 14 (Overfrequency)Instantaneous: freq >70 Hz (60 Hz set) or >58 Hz (50 Hz set).…
- 15 (Underfrequency)Engine governor unable to maintain rated frequency. 60 Hz carburetor…
- 17 (Fuel Pump Fault)Pre-2001 models only. Controller detected an OPEN fuel pump circuit…
- 23 (Oil Pressure Switch Fault)Pre-2001 models only. Continuous open on oil pressure switch input…
- 29 (High Battery Voltage)Voltage across battery system greater than 19 VDC.
- 32 (Low Cranking Speed)Cranking too slow: quadrature frequency ≤3 Hz AND engine RPM ≤100 RPM…
- 33NOT ASSIGNED. If seeing blink pattern that looks like 33, it is…
- 35 (Control Card Failure)Microprocessor EEPROM error during self-test.