Digital Tripmeter does not work correctly.

From Honda Trail Bike Wiki

[edit] Introduction

Sitting above the analogue clock faces, the digital tripmeter offers the rider various distance and time related functions. Unfortunately, a quick check through this website will show many people suffering problems with the tripmeter. The following original information relates to fault finding the tripmeter on an XRV750Y (year 2000 and 24k on the clock) and will grow as the work continues. A genuine Honda owners manual and the Haynes manual number 3919 will be useful to have and may be referred to on occasions.

For correct operation, the tripmeter requires battery power (+12V dc and 0V) and a speed related pulse input. The tripmeter has a continuous power feed from the battery that does not pass through the ignition switch. This allows the microprocessor (uP) to maintain the current set time and any trip distances in memory. Once the ignition is on, a second power feed to the meter is energised and the display is enabled and all information made visible.

The speed related pulse is generated by a small electronic circuit that is mounted in the speedo assembly. As the speedo cable rotates, a moving magnet passes the electronic pick up and a pulse is generated. A pulse is generated for every 'n' cm travelled ('n' to be measured later). By counting the number of pulses, the uP can calculate the distance travelled. If the time taken is also known, then the speed can be calculated. This feature is left unconnected in the standard bike, but may be covered by later work here. Other references to the kmh display feature exist on this website and also on various other internet sites.

Disclaimer(s):

1. Having stripped a lot of my dash it seemed a shame not to share with other @ owners what I have learnt along the way. Read the following and use it as you will - but I cannot accept any liability for anyone messing up their own speedo or tripmeter.
2. All parts lists provided may come with supplier and part number information for each item if known. These part numbers change frequently, especially since the electronics industry went lead free. The main point is to get items rated for voltage, current, power, etc EQUAL TO or BETTER than the ones listed, rather than chase parts which went out of stock months ago

Now, let's start fault finding............

[edit] Speedo Drive Gearbox

For a distance pulse to be generated by the speedo, it has to know that the wheel is turning and the bike is moving.

Most people would check the speedo cable first by disconnecting it from the back of the speedo, however the speedo drive gearbox is the first link in the pulse chain - so we will start here.

Refer to your manual(s) and remove the speedo cable from the output of the gearbox on the front axle. Rotate the front wheel and check that the drive pin rotates smoothly.

If necessary, remove the front wheel and strip and clean the drive components. Replace all worn/broken parts and repack with the correct grease. There is information on this site as to the best grease to use.

Once correct operation of the drive gearbox is confirmed - move onto the speedo cable............

[edit] Speedo Cable

Again, refer to your manual(s) if necessary.

Remove cable completely from the bike. Check cable is not frayed or broken. Replace if necessary.

Clean and lubricate the cable and refit.

Check that speedo works correctly.

Now onto the first of the electronics............

[edit] Speedo Mounted Pulse Generator

It is easier to test the pulse generator if the clocks have been removed from the bike. No mechanical or electrical connection is required to any part of the bike, and the time taken to remove the clocks is easily saved in hassle when performing the tests.

Refer to manuals if necessary - then remove the upper fairing body work. Disconnect wiring looms and speedo cable. Remove clock assembly mounting screws. Remove clocks.

Prior to testing any part of the speedo assembly, you will need to find / borrow;

• 12V dc bench power supply with current limit preferred (or a battery if care is taken to avoid shorts etc)
• Digital Volt Meter (DVM), best quality you can get your hands on [*]
• 10k ohm, 0.25W or better, resistor [*]
• short lengths of solid copper wire (from offcuts of household 'twin and earth' wire is fine) [*]
• a match - fits speedo drive and allows easy rotation by hand
• NEW! Mk2 Speedo tester (use in place of all parts labelled as [*])

[edit] Testing the Speedo Assembly Complete

This is covered by the Haynes manual (page 9.21 in mine), electrical system chapter, "digital trip meter check".

However, electronically it made no sense. You are required to measure a signal that varies between 0 and 0.6V (XRV750Y remember). No normal electronic logic series uses voltages this low for logic high/low indication. The reason became obvious when the PCB was examined (see later), but for now a simple addition to the test will change the measured signal to show between 0 and 12V. Any digital meter should easily cope with this.

[edit] Mk1 Speedo Test Method

Follow link to new page with details for basic speedo pulse generator test circuit.

Mk1 Speedo Test Method.

[edit] Mk2 Speedo Mounted Pulse Generator Test Box

Follow link to new page with design and build details for a new improved speedo pulse generator test circuit.

Mk2 Speedo Mounted Pulse Generator Test Box.

If either test method fails, then there may be an internal speedo fault - continue to next sub-section. Else move onto checking the wiring looms outlined further below in Section 5.

[edit] Internal Speedo Pulse Generator Circuit

CAREFULLY remove the speedo assembly from the main housing. You should aim to remove the parts shown above. The PCB assembly is clearly visible on the rear, along with its 3 wire connection cable.

Front view of the PCB assembly, completely removed from speedo.

[edit] Schematic

Note:

In BLACK = Standard Honda Speedo Mounted Pulse Generator Circuit

In RED = Extra items needed for test, letters in circles are test points, refer to later text

[edit] Circuit Description

D1, R2, ZD1 and C1 form a simple 10V dc regulated power supply rail. This removes the dependance on the vehicle battery supply, the actual voltage of which fluctuates during normal use and operation.

IC1 is the magnetic sensor - type and model currently unknown

R1, D2 and C3 clean up the sensor output into a clean, full rail switching digital pulse

TR1 is the drive transitor, left open collector. This is the reason it is so hard to measure the output voltage as described in the Haynes manual. simple definition of this condition to be found/written

[edit] Parts List

[edit] Testing the Internal PCB

All of the following voltages were measured with the DVM set to volts dc. All voltages are measured with reference to the circuit 0V, (connect the -ve lead of the DVM to circuit 0V). The circuit is to be powered from a 12V supply, connections as marked on the schematic.

Voltages at B and C will change as the sensor detects the passing of a magnet. Use a small magnet (fridge doors usually have a load hanging off them) and carefully move it across the face of the sensor to measure high and low limits. Allow up to 0.5V on your measurements compared to the following;

[edit] Wiring Looms and Connectors

Before moving on to investigate the internals of the tripmeter, spend an hour or so THOROUGHLY checking the looms to and from the speedo assembly and the tripmeter itself. Search for chaffed or damaged looms or wires, and broken or corroded connectors. If using a DVM to perform a continuity check between connectors at both ends of a cable - wriggle the wire carefully to check that connection is good. Many faults can appear to be sound unless checked in this way

Finally - search the forums on this site, many useful references to loom and connector problems can be found.

[edit] Tripmaster Main Unit

Having completed all the steps above, you are left with three options;

• Buy new tripmeter
• Buy GPS unit or similar and replace tripmeter
• Attempt to fault find tripmeter

Which you choose will come down to time, money, knowledge and effort.

If you select either of the first two options - great. There are photos and info on this and other sites for ideas that you can take inspiration from. You need read no further.

Still reading? Then the following sections are intended to outline the work involved in fault finding the tripmeter assembly.

[edit] Getting Started

You will need;

• Circuit Schematic, if you can find one. If you do - post it here!
• 12V dc bench power supply with current limit preferred (or a battery if care is taken to avoid shorts etc)
• Digital Volt Meter (DVM), best quality you can get your hands on - also an oscilloscope may be better if you can get one
• Open collector Pulse generator (see next sections for home made versions), used to fool the tripmeter into thinking it is still on the bike and getting pulses from the speedo

[edit] Mk1 Bench Pulse Generator

Follow link to new page with details for basic pulse generator circuit.

Mk1 Bench Pulse Generator

[edit] Mk2 Bench Pulse Generator

due early 2008 Follow link to new page with details for improved pulse generator circuit with full tripmeter function switching.

Mk2 Bench Pulse Generator

[edit] General Overview of Tripmeter

The tripmeter consists of a small plastic case, 170x70x60mm approx, bolted to a metal subframe by two captive bolts. Access to internals is through the rear cover, sealed against the elements by an o-ring type seal. Electrical connections are made from a single end point loom, into the main @ wiring loom. The loom splits into two branches and enters the rear of the tripmeter, through the rear cover. From the front the operator has four switch/button clusters and the Liquid Crystal Display (LCD) facing them. The actual switches and buttons are PCB mounted, and have the four rubber covers case mounted for better sealing. The LCD is shaded for daylight operation by the case upper face overhang, and is illuminated during 'lights on' operation by a coloured bulb. Internally, a single PCB contains all of the electronic parts, some of which are 'Surface Mount' (SMT) types. A conformal coating has also been applied to the PCB to assist with weatherproofing.

Functionality and operation of the tripmeter is covered in the standard owners manual.

[edit] Removal of Tripmeter and Preparation for Test

Identification of main loom wires and addition of test point loops

Removal of tripmeter from the @ is reasonably simple, but refer to manuals if you are un-sure. For preference, put the bike on its centre stand (if fitted). Unscrew and remove the upper fairing section, complete with screen. You should now be able to clearly see the tripmeter, its mounting bracket and the wiring loom. Unclip the 6 way wiring connector (black on yr 2000) from the main loom. Unscrew the two retaining nuts from behind the mounting bracket (nuts face forward) and remove them and any washers. The tripmeter assembly complete should now slide out of its mounting bracket and lift clear of the bike. If you plan on using the bike, fit a couple of small plastic bags over the empty loom socket to waterproof it, re-fit the upper fairing and away you go.

The tripmeter and its fixings should be moved to a clear, flat and well light work area. Store fixings for refitment later.

The wiring loom enters the tripmeter case in two places;

• Through 'D' shaped rubber grommit near edge of case (behind Trip Time Mode button) - hereafter called the 'Signal loom '
• Through small round grommit (behind Up Down button) - hereafter referred to as the 'Backlight loom '

Gripping the backlight loom as close to the case as possible (on soft rubber moulding) gently wriggle the rubber moulding whilst applying some pulling pressure. The bulb holder should pop out, complete with backlight bulb. This bulb can be removed now for safety (and replacement if necessary). All the backlight bulbs seen to date have been colour coated, this adds colour to the tripmeter display at night.

Remove the six philips screws holding on the rear cover. This cover is fitted with a rubber 'o'-ring seal and there is usually some sticky sealer around the signal loom area too. CAREFULLY remove the loom, rear cover and seal. The PCB assembly should follow, leaving the main main empty. Note: front grey rubber buttons should stay in the case, do not attempt to remove them with the PCB. Pull the rear cover from the signal loom 'D' shaped grommit.

You should now have the PCB and loom assembly in front of you.

Loom Wire Identification Chart (Yr 2000 model)

In order to simplify connection to the PCB, small loops of wire can be added where the

[edit] Tripmeter PCB overview

component id and various circuit functions

ATIC.org have circiut image:

Additonal information on how to modify circuit to display Speed and KMs found at http://www.atic.org/faq/tripmaster.php

[edit] Tripmeter Repair and Modification Case Histories

Update March 08.  It would seem that tripmeters can suffer from multiple issues, each buried inside one another.  
Case 2 tripmeter works well on the bench (initial problems resolved), but only up to 30mph on the road.   
Above 30mph, the trip distance is erratic. Further work will continue after the summer.  
Further work will concentrate on tracing signal paths through the PCB and effective removal of the conformal coating

[edit] Case 1, Speedo Pulse Signal Not Reaching uP

Pulse train checked to Tripmeter PCB input, but uP does not register distance

This case is currently ongoing

new page link to go here

[edit] Case 2, Tripmeter Display Crashes when Button Pressed

When using or setting the Tripmeter buttons, the unit crashes and the display blanks out

This unit has been repaired and is currently under going testing. Pictures and results due Jan 08 - Cancelled due to further problems found during initial road trials

new page link to go here

[edit] Case 3, Modifying the Circuit to show speed in km/h

adding a resistor to get another screen function? may be useful in Europe

new page link to go here

[edit] Suppliers and other Contacts

Inclusion in this list is not the same as a recommendation, however all companies (in my experience) are reputable. Shop around for best deals and prices!

[edit] Electronic Parts

RS (UK)

Suppliers of electronic and mechanical parts, trade counters nationwide (and worldwide too)

Phone: 08457 201201

web: rswww.com

[edit] Miscellaneous

www.xrv.org.uk

Never underestimate the power of this website. Use the wanted forum and wait for the help and offers to come in. Ultra-highly rated.