Module No. 3515
Troubleshooting
Charging with the Charger Cable
Q1The watch won’t charge with the charger cable.
Is the end of the charger cable with the special watch connector securely aligned with the watch charger terminal?
Charging may fail if there is space between the terminals.
Did you leave the watch attached to the charger cable after charging was complete?
Charging stops automatically after the watch becomes fully charged. If you want to charge again, unplug the charger cable from the watch and then re-attach it.
Is charging still impossible after checking the above points?
Check to make sure that the USB device or power source is functioning normally.
Q2Charging stops before it is complete.
Charging may stop if some temporary abnormality occurs. Unplug the charger cable from the watch and check for abnormalities. If there is nothing wrong, try charging again.
If the above does not eliminate the problem, contact your original retailer or a CASIO service center.
GPS Signals
Q1The watch cannot perform a GPS signal receive operation.
Is the watch’s battery charged?
GPS signal reception is not possible while the battery indicator is 
or lower. Charge the watch.
Is the watch’s Airplane Mode enabled?
GPS signal reception is not possible while the watch’s Airplane Mode is enabled. Disable the Airplane Mode.
After checking the above, the watch still cannot perform a GPS signal receive operation.
GPS signal reception is not possible under the conditions described below.
During power saving
Q2The GPS signal receive operation always fails.
Is the watch in a location that is appropriate for signal reception?
Check your surroundings and move the watch to a location where GPS signal reception is better.
Is the LCD of the watch pointed straight up at the sky?
Minimize movement of the watch while the receive operation is in progress.
Also, avoid covering the watch LCD with the sleeve of your clothing.
Adjusting Current Time Settings Using GPS
Q1The watch is not receiving time information.
This model does not support auto GPS signal reception for time adjustment. If you want to receive GPS signals for time adjustment, perform a manual receive operation.
Q2A screen showing that a receive operation is in progress has been on the display for a long time.
The watch may be receiving leap second information.
Q3Signal reception should have been successful, but the watch’s time and/or day is wrong.
Is your Home City (time zone) setting correct for your location?
Change your Home City (time zone) setting so it correctly indicates your location.
After checking the above, the time and/or day settings is still wrong.
Adjust time and day settings manually.
I can’t pair the watch with a phone.
Q1I’ve never been able to establish a (pairing) connection between the watch and phone.
Are you using a supported phone model?
Check if the phone model and its operating system are supported by the watch.
For information about supported phone models, visit the CASIO Website.
Did you install the CASIO WATCHES phone app on your phone?
The CASIO WATCHES phone app needs to be installed on your phone in order to connect with the watch.
Install the required app on your phone.Did you enable location services?
On your phone, configure the settings below. For details about setting procedures, see your phone documentation.
Enable your phone’s location services.
Give your phone rights to use the phone app’s location information.
Are your phone’s Bluetooth settings configured correctly?
Configure the phone’s Bluetooth settings. For details about setting procedures, see your phone documentation.
iPhone Users
“Settings” 
“Bluetooth” On
“Settings” “Privacy” “Bluetooth” “CASIO WATCHES” On
Android Users
Enable Bluetooth.
Other than the above.
Some phones need to have BT Smart disabled to use the CASIO WATCHES phone app. For details about setting procedures, see your phone documentation.
On the Home Screen, tap: “Menu” “Settings” “Bluetooth” “Menu” “BT Smart settings” “Disable”.
I can’t reconnect the watch and phone.
Q1The watch will not re-connect with the phone after they are disconnected.
Is the CASIO WATCHES phone app running?
The watch cannot re-connect with your phone unless the CASIO WATCHES phone app is running on the phone. On your phone’s home screen, tap the CASIO WATCHES icon. Perform the operation shown on the screen that appears to pair with the watch.
Pair the watch with your phoneHave you tried turning your phone off and then back on again?
Turn your phone off and then back on again, and then tap the CASIO WATCHES icon. Perform the operation shown on the screen to pair with the watch.
Q2I can’t connect while my phone is in the Airplane Mode.
Connection with the watch is not possible while the phone’s Airplane Mode is enabled. Disable your phone’s Airplane Mode. On it’s home screen, tap the “CASIO WATCHES” icon. Next, perform the operation shown on the screen to pair with the watch.
Q3I can’t connect while the watch is in the Airplane Mode.
Exit the watch’s Airplane Mode.
Q4I changed the phone’s Bluetooth from enabled to disabled, and now I can’t connect anymore.
On your phone, turn on Bluetooth. Then on its home screen, tap the “CASIO WATCHES” icon. Next, perform the operation shown on the screen to pair with the watch.
Q5I can’t connect after turning off the phone.
Turn on your phone. On its home screen, tap the CASIO WATCHES icon. Next, perform the operation shown on the screen to pair with the watch.
I can’t seem to be able to connect, or connection is unstable.
Q1I can’t establish a connection between the phone and watch.
Have you tried turning your phone off and then back on again?
Turn your phone off and then back on again, and then tap the CASIO WATCHES icon. Perform the operation shown on the screen to pair with the watch.
Is the watch in the Airplane Mode?
Connection with your phone is not possible while the watch’s Airplane Mode is enabled. To connect with your phone, disable the Airplane Mode.
Has the watch been re-paired with the phone?
After deleting the pairing information from CASIO WATCHES and your phone, re-pair the watch and phone.
If you are unable to establish a connection...
After deleting pairing information from the watch, re-pair it with your phone.
Changing to a Different Phone Model
Q1How do I connect my watch to a different phone?
Pair the watch with the phone.
Auto Time Correction by Bluetooth Connection (Time Correction)
Q1When does the watch adjust its time?
Your watch can connect with a paired phone to adjust its time setting. Auto time adjustment is performed at the times described below.
After your phone’s time zone or summer time setting is changed
After 24 hours or more have passed since the last time adjustment using Bluetooth connection
After 24 hours or more have passed since the last home city change or time adjustment using watch operation
Q2Auto time setting is not correct.
Is 
displayed?
To preserve battery power, the watch will automatically terminate Bluetooth connection with your phone temporarily if it detects the connection has been unused for approximately one hour. Auto Time Adjustment is disabled while there is no connection. To reconnect, press any watch button or angle the watch towards your face.
Have 24 hours or more passed since the last time adjustment using Bluetooth connection?
Note that auto time adjustment is not performed for 24 hours after you adjust the time setting manually on the watch. Auto time adjustment will resume after 24 hours.
Have 24 hours or more passed since the last manual time adjustment or city change?
Auto time adjustment is not performed for 24 hours after a manual time adjustment or city change. Auto time adjustment will resume after 24 hours or more have elapsed after either of the above operations is performed.
Is the watch’s Airplane Mode enabled?
Connection with your phone is not possible while the watch’s Airplane Mode is enabled. To connect with your phone, disable the Airplane Mode.
Q3Time is not displayed correctly.
The phone’s time setting may be incorrect because it is unable to connect with its network due to being out of range, etc. If this happens, connect the phone to its network and then adjust the time setting.
Activity Log and Life Log
Q1How much Activity Log and Life Log data does the watch store?
The data storage capacity of watch memory is shown below.
Activity Log: 100 records
Life Log: 3 days
If there is a lot of data, it will take time to transfer the data to the CASIO WATCHES phone app. Frequent connection to the CASIO WATCHES to transfer data is recommended.
Nightly Recharge™
Q1Sleep measurement (Nightly Recharge™) results are not displayed.
Sleep data cannot be acquired when any of the following conditions exist.
Your actual sleep time does not match the current bedtime/wake-up time setting
Sleep (from bedtime to wake up) of less than 4 hours
Wearing the watch only while asleep and taking it off immediately after awaking
Something other than [ON] or [ACTIVITY & NIGHT TIME ON] is selected for the heart rate measurement setting
The watch is not fastened securely to your wrist while sleeping
A minimum of three sleep measurement operations (one of which was the night before) not performed within the past 28 days
Heart Rate Measurement
Q1[ERROR] is displayed during measurement.
There may be a problem with the sensor. Try taking another measurement. If [ERROR] keeps appearing after multiple measurement attempts, contact a CASIO service center or your original retailer.
Altitude Measurement
Q1Readings produce different results at the same location.
Watch readings are different from altitude information available from other sources.
Correct altitude readings are not possible.
Relative altitude is calculated based on changes in barometric pressure measured by the watch’s pressure sensor. This means that barometric pressure changes can cause readings taken at the same location to be different. Also note that the value displayed by the watch may be different from the actual elevation and/or sea level elevation indicated for the area where you are located. When using the watch’s altimeter while mountain climbing, it is recommended that you regularly calibrate its readings in accordance with local altitude (elevation) indications.
Q2[- - - - -] appears on the display following altitude differential measurement.
[- - - - -] appears on the display when the altitude differential is outside the allowable measuring range (±3,000 m (±9,840 feet)). If [ERROR] is displayed, there may be a problem with the sensor.
Q3[ERROR] is displayed during measurement.
There may be a problem with the sensor. Try taking another measurement. If [ERROR] keeps appearing after multiple measurement attempts, contact a CASIO service center or your original retailer.
Digital Compass
Q1The symbol [
] is shown on the display.
Accessing the compass function causes [] to appear on the display. This icon will disappear when you perform a bearing measurement operation.
If [] appears on the display during bearing or activity measurements, it means abnormal magnetism was detected. Move away from any potential source of strong magnetism and try taking a reading again.
If [] appears again, it could mean that the watch body has become magnetized. Move away from any potential source of strong magnetism, perform direction calibration, and then try taking a reading again.
Q2[ERROR] is displayed during measurement.
There is a problem with the sensor or there may be a source of strong magnetic force nearby. Move away from any potential source of strong magnetism and try taking a reading again. If [ERROR] keeps appearing after multiple measurement attempts, contact a CASIO service center or your original retailer.
Q3[ERROR] appears on the display following direction calibration.
If [- - -] is followed by [ERROR] on the display, it could mean there is something wrong with the sensor.
If [ERROR] disappears after about one second, try calibrating again.
If [ERROR] keeps appearing after multiple attempts, contact a CASIO service center or your original retailer.
Q4Direction information indicated by the watch is different from that indicated by a backup compass.
Move away from any potential source of strong magnetism, perform direction calibration, and then try taking a reading again.
Q5Readings at the same location produce different results.
Cannot take readings indoors.
Move away from any potential source of strong magnetism and try taking a reading again.
Barometric Pressure Measurement
Q1[ERROR] is displayed during measurement.
There may be a problem with the sensor. Try taking another measurement. If [ERROR] keeps appearing after multiple measurement attempts, contact a CASIO service center or your original retailer.
Temperature Measurement
Q1[ERROR] is displayed during measurement.
There may be a problem with the sensor. Try taking another measurement. If [ERROR] keeps appearing after multiple measurement attempts, contact a CASIO service center or your original retailer.
Pedometer
Q1Displayed step count is not correct.
While the watch is on your wrist, the pedometer may detect non-step movements and count them as steps.
Also, step count problems can also be caused by how the watch is being worn and abnormal arm movement while walking.
Q2The step count does not increase.
To prevent erroneous counting, the count display does not increase immediately after you start walking.
Q3[ERROR] appears when using the pedometer.
[ERROR] (error) is displayed when sensor operation is disabled because of sensor or internal circuitry malfunction.
If the indicator remains on the display for more than three minutes or if it frequently appears, it could indicate a faulty sensor.
Contact a CASIO service center or your original retailer.
Alarm
Q1There is no sound and/or vibration operation performed for alarms.
Is the watch’s battery charged?
Charge the watch until the battery is sufficiently recharged.
Is alarm sound and/or vibration enabled?
Enable the alarm.
Other
Q1I can’t find the information I need here.
Visit the website below.