Cummins-Onan QD error code 3 (QD)
Service check — a second-level fault is stored. Press Stop once to make the status lamp blink the two-digit second-level code (12–57); look that code up for the specific fault. (3 amber blinks)
What to check, and in what order, is in the app. The flow Onan QD Quiet Diesel — won't crank or stops shortly after start 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.
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- Onan RV Quiet Diesel Operator Manual 0981-0173 (HDKCA/HDKCB)
- Onan RV QD HDKCA/HDKCB Operator Manual 0981-0173 (rv-tech-resources/93-onan-qd-diesel/Onan_RVQD_HDKCA_HDKCB_Operator_0981-0173.pdf)