Hello everyone. I work in a shop in NJ and have slowly been teaching myself the necessities of electronics over the years.

I think I'm more dangerous than anything else, but I'm at a point now where I need to start doing a lot more reading and trial and error. I've been able to successfully understand how to modify a Honda ECU and write a basemap to a 27ST512 chip. Which in itself was a huge feat for me, because I have always been perplexed by the electronics world. But now I feel a little more confident and want to start with something and try to complete it.

I want to learn how to read an IC chip, save the info written to it and write it another IC chip. The specific task relates to the tachometer on an instrument cluster. I purchased a GQ 4X4 and was able to read the 27ST512 Chip, and perform other basic checks. Blank check, etc. But now I am having a hard time identifying the chip that transforms the signal from the ECM to the tachometer. The chip has HML 087 8645 written on it and plenty of Google searching hasn't yielded much.

So I am hoping I can get some direction/assistance here.

https://www.dropbox.com/s/kck3ruabnetfm3x/IMG_5437.jpg?dl=0 - This is the IC chip I would like to read and try to copy.

Also, I would love some suggestions on reading to help open my mind up about this type of learning.

 

Ok... So I think I have a LM2917x-x chip in here.

Essentially an 8 pin frequency to voltage converter?

 

I think I'm more dangerous than anything else, but I'm at a point now where I need to start doing a lot more reading and trial and error.

Why do you think so? Are you sure you used the right expression?

 

Could you identify the pins (who does what)? Have a scope available?

 

Could you identify the pins (who does what)? Have a scope available?

I can't find anything that speaks specifically to what each pin does, I can only find general wiring diagram that go into the Instrument Cluster of the car. I do have basic tools such as a volt meter and a scope on my Snap-On Scanner. Scope allows me to read two signals at a time.

http://www.armchair.mb.ca/~dave/BMW/e30/e30m3_88.pdf - Page 56 is the cluster wiring.

Why do you think so? Are you sure you used the right expression?

Dangerous is the point where one understands concepts but doesn't know enough about a subject. So I am 'dangerous' because I know enough to cause harm. Under most circumstances I usually only learn when I break something and then go backwards to find out why I broke it and how I can do it without breaking the next time.

 

I can't find anything that speaks specifically to what each pin does, I can only find general wiring diagram that go into the Instrument Cluster of the car. I do have basic tools such as a volt meter and a scope on my Snap-On Scanner. Scope allows me to read two signals at a time.

http://www.armchair.mb.ca/~dave/BMW/e30/e30m3_88.pdf - Page 56 is the cluster wiring.

Not easy but you could try to identify what pins are Vcc and Vdd and then the eventual clock / data pins. Maybe there is one or two N/C or just enable pins or similar.

As far as I understand those tables are in EEPROMS what means you just do readings thus never write to them. Not sure about that anyway.

 

The reason I thought that maybe something could be read and written is because here are the plugs.

https://www.dropbox.com/s/s7v27dfnpmffa4u/IMG_5471 (Edited).JPG?dl=0
https://www.dropbox.com/s/6zqkk4sda9rxwkh/IMG_5472 (Edited).JPG?dl=0

The one on the left is the original in the car for the 4 cylinder engine and the one on the right is the for a 6 cylinder engine. Both of these plugs are used for tachometers that read 8,000 rpms. However they are for different cars. Most people need the IC chip on the right put into the board on the left so it fits the car they are doing the engine swap on.

I am basically trying to see if there is something that can be read from one chip (on the right) and written to the other so it accomplishes the same task. Maybe I am also not understanding this correctly. I am basing my thoughts off of very basic electrical knowledge. Most of which comes from me knowing people that manipulated EEPROM chips in the past. So my thinking is that the same can be done here.

Hopefully someone can help guide me into the right direction here.