LiftMaster TDC Installation Manual - English French Spanish - Page 49

Troubleshooting (continued) Symptom Possible Causes Diagnosis Resolution Door runs slowly/at Wall control half speed disconnected or damaged If communications to the wall control is absent, system will run at half speed. LCD Wall control is strongly recommended to be connected. If it is desired to run the system without a wall control, temporarily or permanently, the system can be returned to full speed operation by replacing the wall control wiring with a jumper wire. Operator turns off despite backup battery being connected Operator runs momentarily then stops in limit learn mode If the wall control is present but not functioning, see 'LCD wall control is off or not functioning' Dead or worn batteries Low battery voltage Allow batteries to recharge Replace worn out batteries. Batteries must both be replaced together. Do not mix old and new batteries. Blown battery fuses on main board Visually inspect battery fuses or check continuity If fuses are blown, replace both fuses together Encoder wiring fault Inspect encoder cable for Correct any issues found with disconnection, bad connection, cut encoder wiring cable, etc. Encoder fault or encoder interface fault Go to limit learn process. Number displayed while in door limit learn mode is the encoder position. Jog door several inches in either direction and release button. Number displayed should change. Make sure to cancel changes or set limit again when finished. If encoder position does not change with door movement, the encoder, encoder wiring, and powerhead main board are suspect. Check all three for any visible damage. Attempt power cycling and restoring factory defaults. Replace or repair suspected faulty components. 49