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Curtis Code 73
Stall Detected — controllers 1234 / 1236 / 1238

Possible causes (from the Curtis manual)

1. Stalled motor. 2. Motor encoder failure. 3. Bad crimps or faulty wiring. 4. Problems with power supply for the motor encoder. 5. See Monitor menu » Motor: Motor RPM.

When it sets / how it clears

Set: No motor encoder movement detected. Clear: Either cycle KSI, or detect valid motor encoder signals while operating in LOS mode and return Throttle Command = 0 and Motor RPM = 0.

Effect of the fault

ShutdownEMBrake; Control Mode changed to LOS (Limited Operating Strategy).

Curtis 1234/1236/1238 controllers are fitted to many electric forklifts and industrial trucks (including models from Chinese brands that use Curtis control). If your display shows code 73 with a Curtis controller, this entry applies; the vehicle maker’s manual may add model-specific notes.

Need the part?

For controller, contactor, sensor or throttle parts, send us the code (Curtis 73), controller model and vehicle model on WhatsApp — we quote genuine and OEM parts for export.

Source: Curtis 1234/36/38 Controller Manual, OS 11, Section 8 Diagnostics & Troubleshooting, Table 5. Compiled 2026-10-29. No affiliation with Curtis Instruments.