15. Diagnosis and common errors

Version 1.0Software: FuelTech Vision 3.00.54Firmware: 00.03.00.54Products: FT700, FT700 Plus, FT470, VisionFT2026-10-14

#15.1 Writing and sending

Symptom	Cause	What to do
The Write button is grayed out.	The app is not connected to a unit.	Connect the unit. On the phone, the button also requires an open map.
A message when writing, or Failed to activate the map on the unit.	The cause is in the table in section 13.1.	Follow the table. If activation failed, use Make active on the VCU files screen.
I wrote and the unit's dashboard is still the same.	You edited a target the unit does not use, or wrote to an inactive file.	Check the target (section 2.2). If it was inactive, use Make active.

#15.2 Importing and exporting

Symptom	Cause	What to do
The gauges ended up in the corner or off the screen.	The importer does not check the target or the resolution and does not rescale.	Import only files from the same target; to change targets, use section 11.5.
The background did not appear, the color turned into the theme color or a gauge from the file did not appear.	A file generated outside the app that does not meet the rules in section 13.4.	Check the embedded background (or use Add image in the editor), the color as an object and the gauge type.

#15.3 Dashboard on the unit, values and lights

Symptom	Cause	What to do
The unit starts on the menu and not on the dashboard.	Open the dashboard after startup is not chosen in Startup screen selection.	Choose the option (section 3.2).
A light stays on all the time, or the Shift stays lit.	With no data, the gauge starts visible. With Switch off below (hysteresis) at 0, the light never turns off. A new Shift starts with a shift point of 0.	Enter a value above 0 in Switch off below (hysteresis) (section 7.5). On the Shift, enter the RPM in High alert (section 6.5).
The numbers stopped, or a measurement shows 0 all the time.	After the connection drops, only the RPM resets to 0. With no data, the measurement is 0.	RPM at 0 with the rest frozen: check the connection. Measurement at 0: check the function and the input on the VCU (section 9.6).
The 2-frame light comes on in the middle of the range.	A GIF in Position mode shows the closest frame: it lights at the midpoint between Initial value and Final value.	To light at X, use X minus d at the start and X plus d at the end (section 7.2).
The speedometer scale broke after changing the unit.	The values are stored in km/h. In mph, 0 to 300 becomes 0 to 186.4.	Enter Minimum and Maximum again (section 9.3).

#15.4 Phone and tablet

Symptom	Cause	What to do
I see a dashboard that is not the FT700's, or the dashboard did not change after connecting.	The phone and the tablet show the Mobile and Tablet targets of the map. A map was already open and the app does not replace it.	Edit the right target (sections 11.3 and 11.4) and open the unit's map.
The Dash or Dashboard button is grayed out, or no map is read on connecting.	There is no open map (on the tablet, also no local dashboard chosen), or the options Connect faster by reusing the map already downloaded from the VCU and Automatically download the VCU map upon connection are off in Settings.	Open a map, choose a local dashboard or turn on one of the options.
I tapped the cancel button of the floating button and lost everything.	In the touch editors it asks for no confirmation and discards the changes of all targets.	Save often.

#15.5 Before asking for help

Note the FuelTech Vision version and the VCU firmware version, the device, the target, the exact text of the message and what you did beforehand. Test with a new map, which brings the factory dashboard: if the problem goes away, it is in the dashboard; if it continues, it is in the upload, the connection or the unit. Writing that map also replaces the engine tables and functions: before the test, keep a copy of the current map (section 2.1) and, with the engine off, write the new map from the PC with Save map and activate new map, not with Write, which replaces the active map. That way your map stays on the unit and comes back with Make active (section 13.1). The phone and the tablet always replace the active map.