Trail Tech Display

This section was added when an Explorer owner contacted me after having difficulty starting his bike.  Investigation with K-Scan revealed the coolant temperature was stuck at 55° C.  Unplugging the Trail Tech display cured the problem. 

Note that I've never owned an Explorer and don't have access to a display for analysis.  

The Explorer parts book lists the display as TRAILTECH MULTIFUNCTION, part number 6000030211.  It had a US retail price of $125 back in 2013.  The display has four types of inputs from the motorcycle.

Power Input:  2-position connector.  To the nominal 12VDC power source. 

Speed Input: 2-position connector.  To a sensor that closes a switch once per front wheel rotation. 

Temperature Input: 4-position connector.  In parallel with the coolant temperature sensor. 

Tachometer Input: 2-position connector.  In parallel with the ignition coil primary.

Although the OSSA display looks quite similar to Trail Tech's standard “Vapor” display, I suspect they are not interchangeable.  

Compatibility seems unlikely because the ignition coil primary drive (-350 volt spikes) goes directly into the OSSA display.  Whereas the standard Trail Tech tachometer is inductively coupled to the spark plug wire. 

I also measured a Trail Tech under-sparkplug temperature sensor as 142k ohms at 62° F (16.6° C).   Whereas the OSSA's coolant sensor is about 2850 ohms at that temperature.

An email to Apex Product Group (now providing sales and technical support for Trail Tech) regarding this matter went unanswered.

Internal Photos

The following photos were provided by an Explorer owner.  I don't have the unit in my lab, but will make some educated guesses.  

Based on gap in silkscreen IC markings, there are likely components under the LCD.   This is probably where the microcontroller is located as it's not visible elsewhere.  U8 is a linear 3.3 volt regulator.  

Y1 is a 32.786 kHz crystal.  This is commonly called a watch crystal because you get 1 pulse per second when the oscillation frequency is divided by 32768 (2 raised to the 15th power).   The 3-volt coin cell is a CR2032.  It likely provides power for the time of day clock.

The Microchip Technology logo is visible on U2.  This is likely a nonvolatile serial memory used to keep track of programmable parameters like wheel diameter, MPH versus km/h readout, distance traveled, etc.

MB6S is a 600-volt bridge rectifier.  

1N80 800-volt N-channel MOSFET.