Odometer-Correction.com

[Guest]

Reprogrammed a 2004 Trailblazer cluster, via the direct method, unsolder pin 4 on the surface mount chip, programmed, then reconnected the cluster and the mileage was correct. Person calls me today and tells me ERROR is displayed in the cluster instead of the mileage. I worked fine for 2 days. Any ideas? Could the pin that I reconnected have pulled away again and caused this error?

[DashfixDotNet]

Hello,
The mileage code is corrupted. It worked fine for two days because the main part of the code was the same. Then came the time for the main code to change and this is where the problem occured. The GM used a 3 byte code that repeats 3 times, if one of'em had a wrong byte, at the next main code change you'll get an error. I.E: 20000 miles is 009C....40. At 20096 the code will change to 009D...00. If one of the 3 groups of bytes is not the same then that one will not change and the display will show error. This excludes of course the fact that you may have bad soldering problems; but in such case the display should show 0 mile not error.

Serge

[jnjspdshop]

I see, I only changed the HEX code in 0-20. It is repeated 2 more times?

[jnjspdshop]

Okay took it apart and double checked the code, it was repeated 3 times and was correct. I tried reprogramming it again and it takes and stores the program on the chip but still shows Error on the display when powered up.

Does any have a virgin dump file to compare to?

I assume the cluster doesn't need to be powered when programming?

Someone suggested maybe the chip is bad. Is that even possible because it worked and then it didn't. Could the output on the chip just not work. I can get a new 95020 from mouser would this solve the problem replacing it?

[DashfixDotNet]

Yes it's possible that the eeprom is damaged but I doubt it is the case here. Check the circuitry before taking another direction. You mentioned that you lifted up pin 4 which happens to be VSS (ground) of the eeprom...maybe that very same pin dosen't make good contact with the ground of the circuitry. Solder a wire from that pin to another known good ground of the board and install it back in the vehicle. Also never power up the board while reading or writing the eepom in-circuit or you will damage the eeprom and certainly other components too.

Serge

[jnjspdshop]

[jnjspdshop]

Here is my file for 25,000 miles and it still shows an Error when the cluster is powered back up. Is lifting the #4 pin necessary when reading and writing to this device

[DashfixDotNet]

I do not think it is necessary to lift up pin# 4 but if you're using the programmer I think you use then you must lift that pin up. Professionals always take the whole eeprom off to avoid this kind of situation...at least whenever it is possible. Anyway your first reply is correct. The code should be 030DFF40FFFF.... not the second option filled with 00's between the mileage hex codes. Your second reply with the 25000 miles is incorrect as your file shows 03D0 instead of 030D. In addition to it there are those 00's again. If your pin number 4 is properly soldered, the solder pad on which it is soldered is not damaged, your mileage code is correct and you still get an error message then another part of dataset is corrupted, I mean a significant byte within the eeprom located at a different address of course, used by the processor to read out the mileage codes . Best way to determine it is to load a file or dataset from another car and see what happens. If the error message is still there then look for a physical damage on the circuit board.

Serge

[jnjspdshop]

Okay had a little spare time and decide to play with this cluster more. With the EEPROM on the board I get an Error message in the odometer display field. With the original EEPROM on the board I get Error, along with a newly programmed EEPROM. Once the EEPROM is removed from the board the odometer displays 0 miles. I can't figure out what is going wrong?

[DashfixDotNet]

Hello,
Take a brand new eeprom such as an atmel at25020 (atmel) or a st95020 (sgs-thompson = STM electronics) and load this attached file into it off the board. Then solder it to the board. Make sure you solder it the right way. Pin #4 should be Ground. Power it up and see what happens. If this too is unsuccessful then your processor has a problem or something else is the cause.

Serge
P.S. Make sure your programmer wirtes the file the right way. Some programmers swap bytes to word bytes.

[DashfixDotNet]

Sorry, the files couldn't be attched to my above post. I emailed you the files to your mailbox.

Serge