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The Secret Side of the Original T Touch

by J.Edwards

Most watch technicians who are familiar with the T Touch Expert, and its derivatives such as the Sea Touch and T Touch II, are aware of the diagnostic mode that can be used to calibrate and verify the timepieces’ multitude of functions. Some time ago, I discovered a similar mode by accident, for the E40 305 that powers the classic Tissot T Touch, by unwittingly depressing the center pusher momentarily while installing a fresh battery. While exploring the characteristics of this hidden mode, I happened upon a second, deeper mode, the purpose of which is uncertain. Both modes are likely used for quality control purposes at the factory and I would surmise that the second, deeper mode is used to read or write to the EEPROM of one or more of the various microchips that control the watch’s functions.

The video above demonstrates the various modes and how to access them. The text moves fast, so here is a breakdown of each mode and what it’s known to do:

0.0 – Entry point
1.0 – Tests piezo alarm
2.0 – Tests all segments of the LCD display
3.0 – Tests the motion of the hands
4.0 – Moves the hands exactly one step of the motor once in each direction
5.0 – Performs one full sweep of the dial with each hand in each direction
6.0 – Unknown
7.0 – Unknown. Diplays ‘0t’ on the LCD screen (the inverse of 7.0?)
8.0 – Clears all segments of the LCD display
9.0 – Unknown
A.0 – Entry point for additional hidden modes
L.0 – Unknown
U.0 – Unknown
S.0 – Unknown
E.0 – Unknown

Two additional “hidden” modes discovered on other occasions include ‘C.0’ and ‘10.0’, the purpose of each of which is unknown.

What do you think the purpose of these “unknown” modes might be?

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  1. Jake
    Posted May 27, 2011 at 10:17 pm | Permalink

    Maybe C.O is compass output?

  2. Posted June 1, 2011 at 2:21 pm | Permalink

    That’s definitely a possibility, Jake.

  3. James D
    Posted August 5, 2011 at 9:22 am | Permalink

    I have read on watch forums, that when somebody changed the battery on their Sea Touch, a “tool wrench” or “spanner” appeared on the LCD screen, indicating an error (according to the Sea Touch manual).

    Is there a way to re-set this, so the “tool wrench” dissapears, or does Tissot only have the correct tool to make this error code dissapear?

    I would like to change the battery myself, but was hoping I could re-set the code.

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