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Curtis Code 39
Main Contactor Did Not Close — controllers 1234 / 1236 / 1238

Possible causes (from the Curtis manual)

1. Main contactor did not close. 2. Main contactor tips are oxidized, burned, or not making good contact. 3. External load on capacitor bank (B+ connection terminal) that pre- vents capacitor bank from charging. 4. Blown B+ fuse.

When it sets / how it clears

Set: With the main contactor commanded closed, the capacitor bank voltage (B+ connection terminal) did not charge to B+. Clear: Cycle KSI.

Effect of the fault

ShutdownMotor; ShutdownMainContactor; ShutdownEMBrake; ShutdownThrottle; FullBrake; ShutdownPump.

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 39 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 39), 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.