aaron_h

TD5 Speedo Mileage run up circuit

274 posts in this topic

Having changed a couple of speedos now we have a couple of other hex dumps, I've attached a picture if any one is interested. There are three MPH speedo dumps and one KPH speedo dump.

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Also while opening the speedos up I notice some have bulbs for background lighting and one has had LEDs. I've attached some pictures of the LEDs, are these standard items or are they aftermarket?

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post-25689-0-59836100-1311067876_thumb.jpg

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While the normal bulb holders look like the bulb can be replaced, the LED ones you have pictured look like a complete assembly where the LED is part of the holder.

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With the benefit of some insider knowledge, I can tell you that the LEDs are these.

And, in the dark, very nice they look too!

Nick.

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With the benefit of some insider knowledge, I can tell you that the LEDs are these.

And, in the dark, very nice they look too!

Nick.

Well spotted Nick :) It was of course your speedo they were in so I should have just asked you!

It seemed quite a coincidence as MickeyW and myself had only just been discussing using LEDs instead of bulbs the night before, then of course yours turned up with some in and I assumed (incorrectly) that maybe some of the speedos has left the factory with LED backlighting.

Anyway they are winging their way back to you now fitted snuggly back in the speedo :)

EDIT: I just noticed the price (pack of 10) and they are cheaper than bulbs at my local car parts shop!

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Hi I have just completed the Dash conversion on my CSW. I have a couple of problems still to sort out.

1- Temp Gauge reads to low, just top of the cold line. Did fit the correct sender as instructed on retroanaconda, thought it may be faulty so have replaced it with another. Still same result. I have connected a an electrical feed direct from sender to back of speedo with no difference to gauge. About to change thermostat!

2- Speedo reads double the actual speed I'm doing. I know that this is a result of the transducer. The one I fitted AMR1425 came out of Discovery T/box prob reason it sends double amount of pulses. Thought of buying correct one for Defender Speedo but don't really want to part with another £30 and AMR1425 only has 2 pins therefore I only got to wires going down to it. So I would have to add the 3rd. Thought it may be option to alter programing of speedo?

3- My speedo's odo is at 120800M but would like it to read actaul vehicle mileage of 142400M. Was wondering if Wabbit would be willing to clock it?

At my expense of course!

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AMR1425 is the green topped temperature sender NOT the speedo transducer.

To make the speedo read correctly use transducer YBE100530 it does need the 3 pin connection for the Td5 speedo, the 3 wires are earth/signal to speedo/ 12v power feed.

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Hi I have just completed the Dash conversion on my CSW. I have a couple of problems still to sort out.

1- Temp Gauge reads to low, just top of the cold line. Did fit the correct sender as instructed on retroanaconda, thought it may be faulty so have replaced it with another. Still same result. I have connected a an electrical feed direct from sender to back of speedo with no difference to gauge. About to change thermostat!

2- Speedo reads double the actual speed I'm doing. I know that this is a result of the transducer. The one I fitted AMR1425 came out of Discovery T/box prob reason it sends double amount of pulses. Thought of buying correct one for Defender Speedo but don't really want to part with another £30 and AMR1425 only has 2 pins therefore I only got to wires going down to it. So I would have to add the 3rd. Thought it may be option to alter programing of speedo?

3- My speedo's odo is at 120800M but would like it to read actaul vehicle mileage of 142400M. Was wondering if Wabbit would be willing to clock it?

At my expense of course!

1. Not sure re. the sender. Did you buy a genuine parts temperature sender? Double-checked wiring OK? Does the gauge read full hot if you ground the wire at the sender?

2. I suspect you mean AMR1253 rather than AMR1425 (which as Ralph correctly points out above refers to the temp. sender)? But you are correct, the Disco sender will cause it to over-read. Either fit correct Defender sender as above, or if you can double the pulses-per-mile figure in the speedo head then that will halve the displayed speed :)

3. Send CwazyWabbit a PM and I'm sure he will be able to help you out with your mileage correction, as well as perhaps altering the pulses-per-mile figure as above.

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Hi All

Thats correct AMR1253, my mistake.

1- The sender was corret. The second one I bought was Bearmach one. I have fitted the new thermostat and the gauge reads halfway. Strange I can't recall the old gauge ever reading low. But do recall that during winter the heater didn't get as warm as in the past. I thought the heater matrix needed to be bleed. :)

2/3- I have spoken to CwazyWabbit and he is willing to adjust the mileage and pluses, which is great! :)

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Sorry to dig up an old thread but wanted to ask about this. The video showed the needle at abut 120mph but you said the odometer was reading at 1110mph. That's not a typo is it?

I am doing the same thing on an aftermarket VDO (for a defender 90) with 120 mph gauge and it lets me pulse it up to about 130mph max otherwise just doesn't move. I assume it's to protect the needle or something. At this speed it's going to take 45 days to get to my desired 125K miles so was hoping to make it go faster. I know this thread is on the oem td5 speedo, but has anyone managed to make an aftermarket vdo accept a faster pulse than the gauge allows?

Thanks,

charles


Anyway its now roughly moving at 1110mph.

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Sorry to dig up an old thread but wanted to ask about this. The video showed the needle at abut 120mph but you said the odometer was reading at 1110mph. That's not a typo is it?

I am doing the same thing on an aftermarket VDO (for a defender 90) with 120 mph gauge and it lets me pulse it up to about 130mph max otherwise just doesn't move. I assume it's to protect the needle or something. At this speed it's going to take 45 days to get to my desired 125K miles so was hoping to make it go faster. I know this thread is on the oem td5 speedo, but has anyone managed to make an aftermarket vdo accept a faster pulse than the gauge allows?

Thanks,

charles

1110mph is not a typo, I haven't played with the aftermarket VDO guage just the TD5 VDO/factory ones.

The bit below explains what happens if you pulse a TD5 speedo too fast, have tried a number of them and the max pulse rate they will accept tends to vary between each example.

......

I have clocked the input on this speedo at approx 1.6khz with no adverse affects observed, mileage increased at approximately 25 miles per minute. Any greater frequency and the speedo fails to register a signal. Even so that is about 1500MPH which means you could add 50 000 miles to a speedo in about a day and a half, using a microcontroller You could automate the stop time so you don't overshoot.

......

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Where abouts are you based Charles?

EDIT: The needles are on stepper motors so don't need protecting as such from going too far, I assume the aftermarket is the same.

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If anyone fancies reprogramming their own speedo this programmer looks like it would do the job, and it's cheap at 13 quid delivered from the far east. I've not tried it myself but it does list the memory chip we need to program in it's compatibility list.

http://www.ebay.co.uk/itm/EZP-High-Speed-USB-Programmer-SPI-25-flash-bios-chip-Support-24-25-93-EEPROM-/161266969876

You'll still have some small-ish scale soldering to do.

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Hi CwazyWabbit, et al

Firstly, just spent my morning reading up. Well done on all the work!

I was just wondering if we ever worked out what the 3 pins accessible from the outside are from? Ideally I'd like to not have to rip my speedo open to reprogram it!

Did we document this anywhere? Ie where to set Pulses per mile, etc. I'm currently designing a sender unit for series gearboxes, so it'd be great to know what PPM to set!

Thanks

Thomas

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The factory setting on the TD5 speedo it 4100 pulses per mile. We never got around to working out what the 3 pins were for.

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Ah good: "Published on May 1, 2014" - we did get there first ;)

Kev

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Ah good: "Published on May 1, 2014" - we did get there first ;)

Kev

You're still safe Kev as the mileage algorithm and storage format for the TD5 is different to that. I do like the interface they use for programming the chip though, nice and cheap :)

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The factory setting on the TD5 speedo it 4100 pulses per mile. We never got around to working out what the 3 pins were for.

Understood, really appreciate all the work you've done on this. Going to try and do it without soldering, any ideas if I can get some form of press on connector for reprogramming? I looked at the datasheet but unsure what package the eeprom is.

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You can indeed get clips for that type of chip. It's a SOIC-8 iirc, I'll measure it later if you like to confirm, I've one on the bench.

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You can indeed get clips for that type of chip. It's a SOIC-8 iirc, I'll measure it later if you like to confirm, I've one on the bench.

That'd be very much appreciated. Did you attempt it with a bus pirate at all?

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I had a play with their microwire library but it didn't work for me, although that was quite a while back so things may have changed.

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Idle curiosity got the better of me recently and as there is still no sign of a datasheet for the main processor in the TD5 speedo (the CDVN2117)  I thought I'd take a closer look at it.

If nothing else it is a pretty picture, here's a link to download the picture as it's far to big to post on the forum, try zooming in a bit ;) https://drive.google.com/open?id=0B6XKpDGw3BjiTG9EZkktcF9SSmc

It's really only for geeks tbh.

Looks like it may contain some masked rom so perhaps it's possible to extract some data.

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