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TD5 Speedo Mileage run up circuit


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Well the algorithm helped fill in some of the holes I had in this run. Worst case scenario I guess we could just have a csv file of all the values we know, we could manually work out a good selection above and below the pulse per mile and pulse per km values. Hopefully we can work out the last part of the algorithm though so that isn't needed....

0x0E05 -- 0x45FF

0x0E04 -- 0x46FF

0x0E03 -- 0x43FF

0x0E02 -- 0x44FF

0x0E01 -- 0x41FF

0x0E00 -- 0x42FF

0x0dff -- 0xBEFF

0x0dfe -- 0xBDFF

0x0dfd -- 0xC0FF

0x0dfc -- 0xBFFF

0x0dfb -- 0xBAFF

0x0dfa -- 0xB9FF

0x0df9 -- 0xBCFF

0x0df8 -- 0xBBFF

0x0df7 -- 0xB6FF

0x0df6 -- 0xB5FF

0x0df5 -- 0xB8FF

0x0df4 -- 0xB7FF

0x0df3 -- 0xB2FF

0x0df2 -- 0xB1FF

0x0df1 -- 0xB4FF

0x0df0 -- 0xB3FF

0x0def -- 0xAEFF

0x0dee -- 0xADFF

0x0ded -- 0xB0FF

0x0dec -- 0xAFFF

0x0deb -- 0xAAFF

0x0dea -- 0xA9FF

0x0de9 -- 0xACFF

0x0de8 -- 0xABFF

0x0de7 -- 0xA6FF

0x0de6 -- 0xA5FF

0x0de5 -- 0xA8FF

0x0de4 -- 0xA7FF

0x0de3 -- 0xA2FF

0x0de2 -- 0xA1FF

0x0de1 -- 0xA4FF

0x0de0 -- 0xA3FF

0x0ddf -- 0x9EFF

0x0dde -- 0x9DFF

0x0ddd -- 0xA0FF

0x0ddc -- 0x9FFF

0x0ddb -- 0x9AFF

0x0dda -- 0x99FF

0x0dd9 -- 0x9CFF

0x0dd8 -- 0x9BFF

0x0dd7 -- 0x96FF

0x0dd6 -- 0x95FF

0x0dd5 -- 0x98FF

0x0dd4 -- 0x97FF

0x0dd3 -- 0x92FF

0x0dd2 -- 0x91FF

0x0dd1 -- 0x94FF

0x0dd0 -- 0x93FF

0x0dcf -- 0x8EFF

0x0dce -- 0x8DFF

0x0dcd -- 0x90FF

0x0dcc -- 0x8FFF

0x0dcb -- 0x8AFF

0x0dca -- 0x89FF

0x0dc9 -- 0x8CFF

0x0dc8 -- 0x8BFF

0x0dc7 -- 0x86FF

0x0dc6 -- 0x85FF

0x0dc5 -- 0x88FF

0x0dc4 -- 0x87FF

0x0dc3 -- 0x82FF

0x0dc2 -- 0x81FF

0x0dc1 -- 0x84FF

0x0dc0 -- 0x83FF

0x0dbf -- 0xFEFF

0x0dbe -- 0xFDFF

0x0dbd -- 0x00FF

0x0dbc -- 0xFFFF

0x0dbb -- 0xFAFF

0x0dba -- 0xF9FF

0x0db9 -- 0xFCFF

0x0db8 -- 0xFBFF

0x0db7 -- 0xF6FF

0x0db6 -- 0xF5FF

0x0db5 -- 0xF8FF

0x0db4 -- 0xF7FF

0x0db3 -- 0xF2FF

0x0db2 -- 0xF1FF

0x0db1 -- 0xF4FF

0x0db0 -- 0xF3FF

0x0daf -- 0xEEFF

0x0dae -- 0xEDFF

0x0dad -- 0xF0FF

0x0dac -- 0xEFFF

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0x1080 -- 0xE0FF apply algorithm = 0x170 :(

Remember, you're only after a byte for the answer, so chuck the rest away (and with 0x00FF if you like). 0x170 >> 0x70.

Algorithm still applies.

Kev

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Worst case, you only have to try any value with 8 choices of check bytes, but give me little longer, I'll probably spot it, once my brain has cooled down.

Unless anyone else wants to get there first..? C'mon, only 4 bits left to work out!

Kev

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Worst case, you only have to try any value with 8 choices of check bytes, but give me little longer, I'll probably spot it, once my brain has cooled down.

Unless anyone else wants to get there first..? C'mon, only 4 bits left to work out!

Kev

I found the result of the algorithm for the ones I tried is the same for groups of 16 which makes sense, makes it very to get the next checksum till you hit the end of that group.

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Wabbit, I'm looking forward to you getting your Bus Pirate and posting how you use it, I've ordered one too. Just waiting for it and my VDO speedo to turn up. I had worked out that I need to set my Pulse Per Km rate to around 2400 based on my T/Case ratio, diffs, wheel size etc and was pleased to see that your KPH speedo had revealed a similar value. I will be able to set it through the push-button on the VDO, but I need the bus-pirate to set the Odo to my current distance. I was quoted $160 by a shop to do it and the Pirate is less than half that and should be a bit of fun!

Good work guys!

Ray.

Ray,

Out of curiosity, are you a windows or a linux person? That way once I get the Bus Pirate working I can taylor instructions for your prefered operating system.

I'd be really interested to see your memory dump when you get it extracted :)

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Thought I'd upload some pictures on opening up the speedo as I imagine most people are a bit bored of staring at hex for the last several million messages...

1) & 2) This is the tool I used to prise up the edge of the crimped rim, it's a mobile phone cover removal tool apparently... looks like an electrical screwdriver with a bent tip to me.

3)Stick the opening tool in the gap between the rim and plastic (you'll need to lever against something. Just lever up a little at a time working your way around the rim. Only lever up enough so you can just about get the rim off. The more you bend the rim up the more you have to bend it back again later :)

4) If you look closely you'll see the rim hasn't been bent much and I've been able to force it up with my thumbs. There isn't much of a lip on the white plastic casing.

5) There is an inner black rim that is sort of clipped in, just pop it up with a knife

6) err... it's popped up in this pic.

7) Turn it over and undo the three torx t10 screws to release the guts of the speedo.

8) This is the side of the speedo you will be working on, the memory chip is in the top right corner.

cont.....

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....

9) Just to give an idea of scale, this is the memory chip we need to solder to (or you can buy a special clip if you feel flush)

10) I used thin enamelled wire to make the connections as it means you are far less likely to rip the chip or tracks off when moving the wires about.

11) After the wires were removed and cleaned up with desoldering braid the chip looks mostly unscathed.

12) The rim was re bent by placing the face down on some MDF that had a hole drilled for the reset button to sit in. The speed had light pressure placed on the back with a clamp and then the rim was bent down by lightly tapping with a hammer on a piece of scrap plastic place on the rim.

13) A page from the memory chips data sheet giving the pin connections of the chip.... you'll have to wait for the write up dealing with connecting a programmer up ;)

There will be more pictures when I find them and get organised....

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Ray,

Out of curiosity, are you a windows or a linux person? That way once I get the Bus Pirate working I can taylor instructions for your prefered operating system.

I'd be really interested to see your memory dump when you get it extracted :)

I'm a Windows type, me, and only slightly micro-p savvy. Though I did do a hi-reliability hand-soldering course 30 years ago in the RNZAF!!!

Ray.

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Wabbit, just as an aside, if you need a home for that KPH speedo, I'll take it off your hands for what you paid, plus your handling/Odo setting fee, plus postage to NZ if you want to get shot of it at some point. That way I'll have a backup if I blow it trying to doctor the VDO when it arrives... :unsure:

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So here's what's possibly an interesting twist...

I've spent the day fitting a TD5 speedo (thanks, Landroversforever) but having taken it out for a road trial I find it is reading much higher than it should be. I can't decide if the indicated speed is 2 x the actual speed or 1.6 (which makes more sense, I think) but it's certainly way more than would be accounted for by having the wrong cog in the transfer box. I know the cog is right for the tyre size, anyway.

The speed appears to be a UK spec MPH unit. It has a sticky label on it which says (among other things) "YBC101530" but the '30' has been crossed out and '20' has been written along side it in pen.

So far as I have been able to find out, YBC101530 is a KMH reading speedo, so I wonder if this one has been converted at some point but has somehow lost it's memory of the conversion. I believe it has been stored for a fairly long period without being powered but it still retains the odometer reading. There is no sign of the unit ever having been opened so if it has been converted then it must have been in the factory.

I have not worked out the logic of what could have happened in my head. In any case, this might turn out to be the first 'in anger' application of Mr Wabbit's mph/kmh conversion investigations. I will need the odometer changed at some point as well.

Nick.

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So here's what's possibly an interesting twist...

I've spent the day fitting a TD5 speedo (thanks, Landroversforever) but having taken it out for a road trial I find it is reading much higher than it should be. I can't decide if the indicated speed is 2 x the actual speed or 1.6 (which makes more sense, I think) but it's certainly way more than would be accounted for by having the wrong cog in the transfer box. I know the cog is right for the tyre size, anyway.

The speed appears to be a UK spec MPH unit. It has a sticky label on it which says (among other things) "YBC101530" but the '30' has been crossed out and '20' has been written along side it in pen.

So far as I have been able to find out, YBC101530 is a KMH reading speedo, so I wonder if this one has been converted at some point but has somehow lost it's memory of the conversion. I believe it has been stored for a fairly long period without being powered but it still retains the odometer reading. There is no sign of the unit ever having been opened so if it has been converted then it must have been in the factory.

I have not worked out the logic of what could have happened in my head. In any case, this might turn out to be the first 'in anger' application of Mr Wabbit's mph/kmh conversion investigations. I will need the odometer changed at some point as well.

Nick.

Hmmmm :blink: That's strange, the YBC101530 is indeed on the KMH speedo I have here and YBC101520 is on both of the MPH speedo's I have seen, what confuses me though is that if it had been converted to MPH they would have to have changed the dial face as well.

The config details that we have been playing with that allow the conversion are in an eeprom so shouldn't be able to revert regardless of how long they are disconnected for. Also if the details became corrupted then the checksum wouldn't match and your needle wouldn't move at all. Even if the eeprom fails completely (or is removed) you would notice as the odometer will either read as 999 999 or 0.0 ( I have seen both).

I am at a loss to explain what has happened to yours without seeing it :blink:

To work out what's going on could you do a 10 mile journey measured on your trip meter and also with a satnav and then work it out?

Still on the plus side it will be quite novel to see your landy doing over 100MPH on the motorway ;)

If you'd like me to investigate yours and set your odometer feel free to PM me Nick.

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What brand is your transducer, in the transfer box?

The double-reading is a common problem with Britpart and other non-genuine transducers.

Good point, that would be a simple cause to it..... do they really get the design so wrong as to double pulse it? :blink:

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What brand is your transducer, in the transfer box?

The double-reading is a common problem with Britpart and other non-genuine transducers.

Ahh, OK, i could not find any reference to this when googling earlier but it is indeed a Britpart sender. (I ordered OEM but it came in a blue box).

If you'd like me to investigate yours and set your odometer feel free to PM me Nick.

I will take you up on that offer, but I will get a replacement sender and try that first.

Thanks.

Nick

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Britpart transducers are well known and documented for being hopelessly inaccurate ! Only use a genuine Land Rover speedo transducer.

HTH

Mo

And as for the build/assembly quality.... this is fresh out of the blue-box...

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Didn't you say in your other thread that it's just a reed switch and a magnet? If so at 60 mph it would be switching almost 70 times a second .... that sounds a lot to ask of a mechanical switch to me.

I wonder if the genuine one has different internals? Maybe a semiconductor based solution better suited to that speed of operation.

Has anyone looked in a dead genuine one?

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I had a blue box one before I sent it back for a genuine item. The construction was the same, but the BP one was very poorly finished. The moulded part was so loosely clipped to the die cast piece, you could just pull it apart with fingers. I didn't bother finding out whether it worked.

The gen item looks like a quality component and works perfectly :)

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Most of what you are all talking about is complete double dutch to me!

But I've been following with interest because this has been on my to do list for a while.

Decided I would get the td5 Binnacle ( which I got off Ebay about two years ago) out to see what mileage was on it, however I've tried putting 12v onto pins 6 & 11 and pin 1 of the loom (and even all together) but the Speedo wont light up. Am i doing something wrong or is my speedo dead ? :( - Btw I've also been putting pin2 to earth/Neg.

Thanks Mark.

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It's OK i've worked it out now.

If you want to test it via the loom you have to use pins 7 or 9 for the earth, pin 2 is only the earth for the lighting circuit.

So my speedo works and is only 5K low :)

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I'm pleased to be able to report that a new genuine LandRover transducer arrived in this morning's post. It took all of 10 minutes to fit (including putting my overalls on first and taking them off again afterwards) and I now have a rock steady speedo reading which I find entirely believable.

Credit also to Duncan and his colleagues at Brit-Car for sorting me out with a credit for the faulty Britpart item and supplying a genuine replacement as well as a some other bits with no hassle or fuss.

Nick.

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