Leica TS16 EDM Not Measuring Distance: Causes and Solutions
Quick Answer
The TS16 EDM not measuring distance issue has several documented causes. Identifying the correct cause immediately directs you to the right fix.
What Causes Edm Not Measuring Distance on the TS16
The TS16 EDM not measuring distance issue has several documented causes. Identifying the correct cause immediately directs you to the right fix.
- Incorrect prism type selected (mini vs standard vs reflectorless)
- Target below minimum EDM range (typically 1.5m minimum)
- EDM laser window dirty or damaged
- EDM settings in wrong mode (reflectorless vs prism)
- Firmware bug with specific prism type
How Serious Is This Issue?
TS16 EDM not measuring distance ranges from a minor setup correction to a hardware failure requiring service. Continuing to work through EDM not measuring distance without diagnosis risks producing inaccurate or unusable data — the cost of diagnosis is always less than the cost of rework.
Step-by-Step Field Diagnosis
Work through these steps in order. Do not skip to later steps before completing earlier ones.
- Verify EDM mode matches target type: The Leica TS16 has three EDM modes: Prism (for glass prisms), Reflector (for reflective tape), and Reflectorless/DR (for natural surfaces). Using Prism mode pointed at bare concrete will fail to measure; using Reflectorless mode pointed at a glass prism produces incorrect distances. Verify current mode in Leica Captivate Settings > Survey > EDM Type.
- Check prism type setting matches physical prism: Within Prism mode, specify the prism type: standard (GPR1, GPH1), mini (GPR111), or 360° (GRZ4, GRZ122). Each prism type has different reflectance characteristics and requires different EDM compensation. Using the wrong prism type setting causes measurement failure or systematic distance error.
- Clean the EDM laser window: The TS16 EDM emits through a small window on the instrument face. Fingerprints, dust, or concrete overspray scatter the outgoing beam and prevent measurement. Use optical cleaning cloth and lens cleaner. Even minor contamination of the EDM window — not visible to the naked eye — can completely prevent distance measurement.
- Check minimum measurement distance: The Leica TS16 EDM has a minimum measurement distance of approximately 1.5m to a standard prism. Attempting to measure shorter distances produces an error. Move the prism to at least 2m from the instrument for initial testing.
- Test with a known-good prism at known distance: Set a standard prism at exactly 50 meters (measured with tape). Aim the TS16 and command a distance measurement. Compare the measured distance to 50m. If measurement succeeds but is incorrect, the EDM is functioning but needs calibration. If measurement fails, the EDM hardware or laser diode requires service.
- Update TS16 firmware: Leica releases TS16 firmware updates that include EDM improvements. Several firmware versions addressed specific prism recognition issues. Connect to Leica Exchange and check for available updates for your TS16 serial number.
When to Send for Service
Send to Leica authorized service if: all six steps above produced no improvement; the instrument was dropped or impacted; error codes persist after power cycling; or the issue is recurring and worsening.
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Service: expresstools.com/service — Express Tools facilitates Leica authorized warranty and out-of-warranty service.
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Frequently Asked Questions
What is the EDM range of the Leica TS16?
The TS16 measures to a standard prism at up to 3500m under good atmospheric conditions. With reflective tape, range is approximately 250m. Reflectorless/DR mode measures natural surfaces to approximately 500m (white surface) or 1000m (retro-reflective). EDM range is reduced in rain, fog, and haze.
What is Leica TS16 EDM accuracy?
EDM accuracy on the TS16 is ±1mm + 1.5ppm for standard prism measurements. At 100m, this is ±1.15mm. At 1000m, ±2.5mm. Reflectorless accuracy is ±2mm + 2ppm — less accurate than prism measurements. For precise layout requiring ±5mm or better, use a standard prism rather than reflectorless.
Does Gradelog work with Leica TS16 data?
Yes. Gradelog accepts Leica TS16 data from Leica Captivate exports. Use for airport grade verification, construction layout as-builts, pad elevation surveys, and DOT QC records. Gradelog tracks TS16 calibration due dates and service history. Free to start at gradelog.com.
Why does Leica TS16 give EDM error in rain?
Water droplets in the air scatter the EDM laser beam, absorbing and deflecting it before it reaches the target. This reduces return signal strength below the detection threshold, causing EDM failure. The TS16 itself is protected to IP54 and can operate in rain — the issue is atmospheric attenuation of the EDM signal, not instrument damage. Shorten measurement distances in rain, use a prism rather than reflectorless, and avoid measurements through rain curtains.
What does EDM error code 118 mean on Leica TS16?
Error 118 typically indicates insufficient signal return — the EDM beam did not receive enough return signal to calculate distance. Causes: target too far, target at wrong angle (prism face not toward instrument), dirty EDM window, or wrong prism type setting. Verify line-of-sight is clear, prism face is aimed at instrument, window is clean, and prism type matches setting.
How do I enable reflectorless mode on Leica TS16?
In Leica Captivate, Settings > Survey > EDM, set Target Type to "Reflectorless" (DR mode). A visible red or infrared dot appears on the surface when aimed — this is the EDM target point. Point the dot at the surface, measure distance. Reflectorless mode works on any surface but is most accurate on flat, perpendicular surfaces.
