Questions about "Wiring a Cat" to bypass speed sensor

[C. Harlan]

I am sure some of y'all have heard of doing this. . Its where you run a wire from a power source (Interior light) and hook it into a wire that somehow bypasses the speed limiter on a computer somewhere in the truck. I know it used to work, but my question is this. . A friend drives a Pete 379 with a 455 Cat. It is cut back to 70 MPH. . Is there a way to bypass this and let the truck run as fast as it is designed to, maybe without having to go to the CAT house? Are these motors still able to be "wired"??? I am sure there are some CAT Gurus out there somewhere... Any and all replies would be appreciated!



-Chris-

 

[CPjMech]

You can't really get around the vehicle speed limit set in the eng comp. If you unplug or tamper with the speed sensor the VSL protection kicks in and limits eng rpm. Most CAT houses will change the VSL for free if the truck is driven by the owner. I know alot of the guys out here are having the VSL set pretty close to the speed limit because of the insurance liabilities. Some ins co's are even requiring a print out of the eng ecm to prove the VSL is set down.

 

[C. Harlan]

Is there a way to clear the parimeters set by the owner? It is a company truck, but it is set to 70, and it cannot climb the big hills without lugging and having to downshift... If you disconnect the batteries and leave the key on or something, will it clear the computer program and go back to original specs?? Just a question.



-Chris-

 

[CPjMech]

There is no way to clear or blank the ECM to reset it, + the customer parameters can be password proteted too. Most places will not change parameters on a company truck without permisson from the co because the ecm leaves a tattle tail with the serial number of the service tool used to change anything. Sounds like he is pretty much stuck with it.

 

[MMiller]

cpjmech is right on the money. The Cat techs can change the parameters with ease. Heck my laptop is out in the service truck. BUT there is probably company password, and the company would have to give the password to the mechanic and then the tech could get in a change it. I changed vehicle speed limit in my service truck, luckily it was not password protected.



If the truck is over geared, sounds like driver needs to drop a gear, set the cruise(it probably is set higher hp at cruise then gaspedal) and enjoy the ride. 455 ought to run pretty well down the road, unless gearing is wrong. Also fuel economy falls off a LOT at higher speeds in any truck, let alone a pete.



Michael