Any Electronic Controlled Transmission Guru's jump in here. I have been trying for some time to find info on keeping my converter locked up when I want it locked on my 04 F150 4X4 Lariat SCREW. Haven't found squat as yet so I thought I would try our forum. I have a total custom 53 Pickup with a warm GM 350 and a 700R4 Tranny that I can flip a rocker switch and keep the converter locked until about 15 mph when I want. As I said before, I've checked with all the transmission guys I know and online but can't get any info on the R75 Ford tranny. At 13.5 MPG it would be nice and improve the Gas Mileage some as it sure did in my 53. I bought the 04 Lariat new here in Hawaii when we didn't have any Ethanol added and was getting 16 mpg but dropped 2.5 when the Gov shoved that you know where. Gas is always over $4.00 here on the Big Island. I found lots of do it yourself info on this matter but nothing on the late model ECU controlled ford trannys. I bet its just a matter of one wire, Hot or Grd. but I don't want to fry my ECU experimenting. Been there, done that. Any help/info greatly appreciated, Renzo

 

The best way to do this is through a custom tune. Doing it manually via a switch is going to cause the computer to have a fit and probably do more harm than good. I definitely would not do this manually.

More than fair warning.

That said, the computer switches ground instead of positive 12v and an isolation relay would be needed to prevent feedback to the computer.

D

 

Thanks for that info Darrin. I already have a EDGE Tuner on it now for several years and have changed my shift points as much as it will allow but this is not what I'm after. I can find info even in our Forum and all over the web on how to do this on Diesels and Gas powered trucks 1995 and older but not anything on the ECU controlled Ford R75 model tranny. A few months back I did locate one company making a controllable black box for Hot Rodders they say works on the R75 and locks up the TC however and whenever you want it for Drag Racing. It is a controller with a **** installed inside the cab that is plug and play, so they say. They told me you unplug the wiring coming from the ECU, plug their wiring in and run a hot 12v lead and ground to the box. I'm not so sure about this and they want $650 for it. You can find all kinds of lockup gizmos for the GM 700R4 like I have in my 53 but nothing so far for the Ford R75. Kinda like our vacuum front hubs no one has yet made manual conversions for. Don't want to start on that. Any more comments or good info would be greatly appreciated. Renzo