pcmhacking.net

I have a strange question about vehicles that use the GenIII engine management systems (specifically the 12200411). I know that the odometer is digital on the dash for these vehicles. What I'm having trouble trying to find is where that "miles driven" value is stored? Is it stored in the PCM, or in the circuitry of the cluster itself? Maybe the body control module?

I ask because I'm attempting to create some stepper driven dash gauges for my 1953 GMC project (controlled hopefully by a 0411 PCM). As I work on the design for this project, it occurred to me that I will need to store (in non-volatile memory) the "miles driven" value in my gauge system so it can always be available for displaying on a small lcd. My goal is to try and build some gauges that look as stock as possible, but can communicate with the 12200411 PCM. I'll be using a small microprocessor(s) to control the gauges. That way I can input stock GenIII engine management sensor signals and convert those signals for practical use. Probably an Arduino, or maybe even a PIC.

If the PCM already stores this value, then it's less work for me!

I hope that all made sense.

Thanks in advance for your thoughts on this.

Take care,

David

AFAIK it's in the dash cluster(small 8 leg eeprom) but whether it's stored anywhere else is another question for the experts!

Yeah its not in the pcm at all, its in the cluster, which has that, and also other settings eg air bags, pulses per km (or mile) for measuring distance, tacho pulses per revolution etc... Things like temperature though are sent from pcm as data. Fuel is an analog signal with programmable levels.

I used Classic Instruments and have never regretted it ...

-Enjoy
: )_~

Thank you for the help on this! I really appreciate it. I think I'll get my hands on a gauge cluster from a 2001-2002 Silverado and take it apart. I'm thinking it will teach me something...

I'm more of a machinist and fabricator than someone who works in electronics. So, I kind of rely on other peoples experiences to help me stumble through my projects that involve the moving of electrons...

Gampy, Man I would LOVE to use something created by Classic Instruments! My budget though is not as large as I would like. Besides, isn't it the greatest thing ever to learn something new!?

Thanks again for the help!

Take care,

David

DavidBraley wrote:Gampy, Man I would LOVE to use something created by Classic Instruments! My budget though is not as large as I would like. Besides, isn't it the greatest thing ever to learn something new!?

Yes it is ... However my time and pride is worth something as well.
Budgets never are enough, it's all a matter of choices for the end result.

I know I could never match their quality for the cost ... It is something right in your face, if it ain't right you can't look around it. Been there done that have the t-shirt and wrote the book!

Then again, I'm super anal and a slight wow (slight imperfection) would look like a HUGE GOOEY RED FACE PIMPLE sticking it's tongue out at me!

Have you even talked to them about what you want and the cost, you may be pleasantly surprised, I was.

-Enjoy
: )_~

Gampy wrote:
Have you even talked to them about what you want and the cost, you may be pleasantly surprised, I was.

It's interesting you bring up Classic Instruments. I have been subscribed to their email news letters for years. I would love to tour their facility someday in Boyne City, MI.

I haven't talked to them on the phone, but their website says they want $874 for something that I find not exactly what I want, but beautiful all the same. I've heard nothing but great things about this company!

If this idea I have of making my own gauges starts to turn into a free fall down "the rabbit hole", I will definitely give them a closer look.

Take care,

David