Mast Up-Limit Switch Failed to Open at Full Extension
The ALLMAND-10 (COMMANDER) diesel fault code means: Mast Up-Limit Switch Failed to Open at Full Extension. This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $15-$80 DIY for switch and cable replacement. Professional diagnosis and repair typically $150-$400 including labor if wiring harness or controller input is involved.
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Common Symptoms
- COMMANDER display shows fault code 10 during tower raise sequence
- Tower stops raising before full extension or raises past the normal stop point
- Hydraulic pump keeps running after mast should have reached the top
- Lights do not illuminate after raise sequence because the controller never confirmed full extension
- Yellow or red fault indicator on the COMMANDER panel lights up during or after tower deployment
- Tower raise sequence completes but COMMANDER does not transition to RUN mode automatically
- Repeated fault code 10 every time the tower is raised, even after reset
Probable Causes (Ranked by Likelihood)
- Up-limit switch contacts stuck closed or corroded shut, preventing the open signal at full mast extension Very Likely
- Limit switch actuating cable or rod is stretched, broken, or has slipped off the pulley, so the switch never gets physically tripped Very Likely
- Wiring between the up-limit switch and the COMMANDER controller is broken, chafed, or has a corroded connector, creating an open circuit that mimics a failed switch Likely
- Up-limit switch mounting bracket is bent or shifted so the actuator arm no longer contacts the mast flag or cam at full extension Likely
- Hydraulic cylinder worn or leaking internally so the mast never fully extends to the point where it would trip the switch Possible
- COMMANDER controller input for the up-limit circuit has failed internally Less Likely
Step-by-Step Diagnostic Procedure
Before doing anything, lower the mast fully and set the panel to OFF. Lock out the hydraulic valve so the mast cannot move while you work near it.
Locate the up-limit switch on the mast head or upper mast section. On most Night-Lite Pro II units it is a small micro-switch or plunger switch mounted to a bracket near the top of the inner mast tube. Inspect it visually for cracked housing, bent actuator arm, or obvious physical damage.
Check the actuating cable or rod that runs from the switch arm down to the fixed reference point or cam on the mast. Pull on it gently. It should be taut with no slack. If it is limp, broken, or has jumped off a pulley, that is your fault. Restring or replace the cable before proceeding.
Disconnect the two-wire connector at the up-limit switch. With the switch disconnected and the mast fully lowered, use a multimeter set to continuity or resistance. Press the switch actuator arm by hand. You should see continuity (closed) when the arm is not tripped, and open circuit when the arm is fully depressed, or the reverse depending on normally-open vs. normally-closed wiring on your specific unit. Confirm the switch changes state cleanly with no bouncing. A switch that reads open in both positions or never changes is defective. Replace it. Standard micro-switch replacement costs about $8-$20 at any electrical supplier.
With the switch connector still disconnected, inspect the wiring harness from the switch down to the COMMANDER controller. Look for chafed insulation, pinched wires at mast joints, or corroded pins in the connector. Measure continuity from the switch connector pins down to the COMMANDER input terminal. Any break means a wiring repair is needed before the switch can signal correctly.
If the switch and wiring both test good, raise the mast slowly while watching the switch actuator. Confirm the mast cam or flag actually contacts the switch arm at full extension. If the mast stops 2-3 inches short of where it used to stop, suspect a weak or leaking hydraulic cylinder. Check hydraulic fluid level at the reservoir. Low fluid will prevent full extension.
After any repair, raise the mast fully and confirm code 10 clears on the COMMANDER display. If the code persists with a confirmed good switch, good wiring, and full mast extension, the COMMANDER controller input may need to be evaluated by a qualified technician with a controller-level diagnostic tool.
Frequently Asked Questions
What does Allmand code 10 mean?
Code 10 means the COMMANDER controller raised the mast but never received the signal from the up-limit switch confirming the mast reached full extension. The switch is a small electrical sensor that tells the controller it is safe to stop the hydraulic pump and turn on the lights. When that signal does not arrive, the controller flags a fault instead of continuing the auto-raise sequence.
Can the light tower still operate with code 10 active?
It depends. If you can manually complete the raise and override the fault on the COMMANDER panel, the lights may still power on. However, running without a confirmed up-limit signal means the controller cannot protect the mast from over-extension on future raises. You should repair the switch before putting the unit back into regular service.
How much does it cost to fix Allmand code 10?
If it is just the limit switch, parts cost $15-$40 and a mechanically confident technician can swap it in about 30-45 minutes. If the actuating cable needs replacement, add another $20-$30 in parts. A rental yard shop or mobile mechanic will typically charge $150-$400 all-in depending on whether wiring repairs or mast disassembly are needed.
Will this fault prevent me from deploying the tower on my next job?
Very likely yes if the code is still active. The COMMANDER controller may halt the automatic raise sequence and require a manual override each time. On some firmware versions, a persistent code 10 will prevent AUTO mode from completing tower deployment entirely. Fix the switch or cable before the next event or jobsite deployment.
10 on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown: