Heres a tutorial on how to reprogram your odometer by yourself at home using $10 in electronic components. This was demonstrated on a Honda Accord.\r
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Reprogramming an odometer is done to correct the mileage on the instrument cluster after repairing or swapping clusters. \r
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Full write-up available for download here:\r
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Tutorial:\r
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Odometer Calculator Spreadsheet:\r
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Disclaimer:\r
1. The information provided should only be used to correct mileage information. While it is not illegal to change your odometer reading, it is illegal to falsify or misrepresent the ual mileage of the vehicle. \r
2. The odometer display can be easily falsified by swapping clusters to one of a lower mileage.\r
3. This procedure requires disassembly of the cluster, and de-soldering of SMD components. Use care and caution when dealing with delicate components, and price first on a spare cluster\r
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The mileage on most (Japanese) cars is stored on the instrument cluster itself, and not in the ECU. Therefore the mileage of the original vehicle that the cluster was from will be displayed on the dash.\r
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Odometer information is stored on a small EEPROM chip on the circuit board. The chip can be read and written to using a serial programmer. The information is coded in hexi-decimal charers.\r
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Odometer correction can be performed using expensive hands on tools, including Honda HDS software. This tutorial demonstrates how you can program the chip directly using nothing but a few resistors, zener diodes and your trusty old computers serial port.\r
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Tools and Parts Required:\r
• Screwdrivers\r
• Soldering iron, solder and a de-soldering pump\r
• Computer with Windows XP and serial port\r
o Wire strippers \r
• Serial programmer \r
- Breadboard\r
- Hookup wire\r
- Female serial port header\r
- 5V from computer power supply\r
- 4.7K ohm resistors\r
- 5V Zener diodes\r
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• Serial programming software (PonyProg freeware) \r
• A spare instrument cluster in case you screw up\r
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In this case the original cluster read 314K km, and the new cluster read 211K km. The new cluster was then programmed to match the 314K that is on the vehicle.\r
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The cluster must be disassembled to access the L56 EEPROM chip. It must then be desoldered from the board to enable writing to the chip. Care must be taken when desoldering SMD components, as mine broke and I had to find a replacement 93C56 chip.\r
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Once the chip is connected to the simple serial programmer circuit, it can then be read and written to using PonyProg software.\r
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The odometer information is stored in HEX charers, to which an attempt was made to decode. The odometer information is stored in the bottom rows, which were then edited with the new corresponding HEX charers and its checksum, and then written to the chip. \r
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Once the chip is soldered to the board it can then be powered on to test the new instrument cluster. The major part of the mileage (thousandths) was decoded, so it matches close enough but not perfectly. \r
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An easier option would be to desolder the chip from the old cluster and solder it to the new cluster. Or you can read the info from the old and write it to the new.\r
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Just for fun you can program 999,999 and go show some dealerships as a potential trade in. Im sure theyll be shocked.\r
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Reference material:\r
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