55V Circuit Below Range (Code 17)

Step 1 — Inspect the flywheel magnets**

Remove the flywheel cover and visually inspect the permanent magnets on the inside of the flywheel. Look for surface rust, cracks, or white powdery corrosion. Corroded magnets have a reduced magnetic field and generate lower stator voltage. Clean light surface rust with a fine abrasive cloth. If magnets are cracked or have lost material, the flywheel must be replaced.

Step 2 — Test the capacitor**

The capacitor is mounted near the EMM and buffers the 55V rail. Before testing, the capacitor MUST be discharged.

Discharging:* Momentarily connect a jumper wire between both capacitor terminals and a clean engine ground. Keep contact brief — a small spark is normal.

Testing (ohmmeter on HIGH ohms scale):*

- **Good capacitor:** Resistance starts low, then rises steadily and climbs toward nearly infinity as the capacitor charges from the meter's internal battery. The needle or reading will continue to increase. - **Shorted capacitor:** Immediate full continuity (resistance stays at or near zero). Replace immediately. - **Open-circuit capacitor:** No reading at all — meter shows OL/infinity from the first moment and does not move. - **Note:** If the initial reading is negative (analog meter deflects backward) or the resistance begins to decrease rather than increase, the capacitor still holds stored charge. Discharge again and retest before drawing conclusions.

Step 3 — Test the stator resistance (static test)**

Disconnect the stator connector from the EMM. Using a multimeter on the Ω setting, measure resistance between each stator lead pair: - Resistance between any two yellow AC leads should be within 0.1–0.5 Ω (check your service manual for your specific engine HP) - Measure from each yellow lead to engine ground — should read OL (no continuity). Any continuity to ground indicates a shorted winding. If any winding reads open or shorted to ground, the stator must be replaced.

Step 4 — Test the stator output (dynamic test)**

With the stator reconnected and a multimeter set to AC volts, probe the yellow stator output wires while cranking or running the engine: - At 500–1,000 RPM: minimum ~45V AC between leads - Above 1,000 RPM: minimum ~52V AC between leads Low AC output with correct winding resistance suggests the flywheel magnets are weak rather than the stator winding itself.

Step 5 — Check EMM cooling**

The EMM has a water-cooled heat sink fed by a small cooling line from the engine's raw-water circuit. Check that this line is connected, not kinked, and that water flows through it when the engine runs. Blocked EMM cooling causes internal thermal protection that limits 55V output. Inspect the O-ring seal on the cooling inlet.

Step 6 — EMM as last resort**

If the flywheel, capacitor, stator, and cooling system all test good, the fault lies in the 55V rectifier/regulator circuit inside the EMM. This is an internal repair. Ship the EMM to Hardware Care — no cure, no pay.