1985 Mustang Up Shift Indicator Modification

[CoastieLT]

Working on a 1985 Mustang GT 5 Speed car. I was investigating the Up Shift light in the dash because it is not working. After some research I realized it was designed to improve fuel economy and turns on when several parameters are met and at about 2000 rpm.

Since that is less than helpful, I was curious if anyone has replaced the upshift module with an RPM Activated Switch like the one from Summit (SUM-830453)? The goal would be to have the in dash shift light operate at a programmable RPM (like 6000). Any issues that I need to be aware of? Thanks.

[CoastieLT]

Looks like nobody has tried this yet. Unfortunately my car is not running and it is going to be awhile before I try it out myself, but I did a little more research and made a drawing to show how I think the modification would work.

This should allow a programmable RPM level to energize the existing upshift light in the dash. I would expect this to be particularly useful if your light does not work and you have removed any of the three controls (Vacuum switch, Vacuum coolant electrical switch, or top gear switch) that are part of the stock circuit.

Not responsible if you fry something.