Is there a way to have a shift light if you have an auto? 8746. If there is, this could be nice instead of having to pay for a MSD shift light, I could build one. Or it could be an RPM activated switch. If this can be done, please tell me how. Thanks

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, Jon (350 TBI!)
91 Red My website

 

You'd need a complete hac of that to find out. Often you can use say the charcoal canister purge for something like that. With each ecm it means reading thur the code and being somewhat clever.
there was a shift light diagram on one of the Japenese car lists

 

Grumpy is right, in fact, you will most likely need to alter the actual Source Code and re-assemble it with new instructions.

You basically need to copy the routine that calcs the "shift light" from the Manual Xmission subroutine and paste it into the Automatic Xmision Subroutine. Not terribly hard if you know Assembly Language programming. But you need to develop Source Code for your ECM first by dis-assembling it and then "tweaking it" (dis-assembling never gives you perfect Source Code).

But, if you TRULY want to get into Assembly Language programming, it is a good place to get your feet wet. And then, you open up a WHOLE NEW AREA for EPROM burning. Now you can make the ECM function as you WANT instead of how GM wanted.

Currently, I am working on Source Code to pull some Spark Advance out when my car upshifts. I find I encounter audible knock when the car is upshifting, and I either have to back off my timing (a lot) or make the ecm to temporarily pull out 4-6* of spark while the upshift is occurring. Unfortunately work is consuming a lot of my personal time, so I haven't been able to dive into this project as much as I want to.