Any of you PIC microcontroller guys out there: I'm working on a speedo recalibration program for a 16F628A that will take a VSS input signal of one frequency, mulitply it by some recalibration factor, and output the result to the speedometer. I'm just starting programming so don't hammer me too bad.. I've got a program written but haven't tested it any further than hooking a speaker up to the output and generating some random frequencies (noisy switch contacts) on the input.

I'm not sure exactly how the 730 ECM formats the VSS signal for the speedometer. I'm assuming that it's a 0-5V square wave, with a 50% duty cycle, ie. the HIGH and LOW pulses are equal in duration. I wrote the program to actually measure VSS signal pulsewidth, so duty cycle is important.

A circuit could also be designed to generate a square wave from the reluctor output, however I haven't looked into or found a need to design something like that yet.

I've seen this tread and others, but I still think it might be nice to have a cheap alternative to a dakota box when one is required.

Here's the assembly and hex files, I wrote the program in MPLab, so formatting of the assembly file might be off if you open it up in a different type of editor. TGO doesn't allow posting non-image attachments, so I had to put them up elsewhere:

http://home.cinci.rr.com/bnoble

 

Haha, rock lobster.

I stopped at ROCK LOBSTA.

I've always thought about doing my own fan controller, including reading the VSS and deciding not to turn on the fans above a certain speed, A/C, etc. But, like the SGI-5, I think their product is pretty nice AND it's still made in the US....

 

https://www.thirdgen.org/techbb2/sho...hreadid=346332

Try this thread, might have some more info for you

later
Jeremy