Check Engine Light on Cummins Engine

[Big Scooter]

I have a Cummins 300 ISC engine and am having a Check Engine warning light that stays on most of the time, with a code 128 indication. The Engine Cooling fan is staying on as long as the check engine light is on. I've had the High pressure Fan Swith replaced twice but it doesn't help. Just wondering if anyone has had this problem before. Cummins is working on it.

 

[doe.mouse]

What did Cummins tell you a code 128 meant? My check engine light did that, but I don't remember the code number. They said it ws a false reading and told me how to re-set it.

 

[Joe]

Hello Big Scooter

128 is a generic code that the computer uses to communicate with the
various components
I have RoadRelay 3 tm installed in my truck
http://jroman.com/mytruck2.html
which, like your truck has a Cummins CELECT tm Engine.
Cummins CELECT tm Engines are completely electronically controlled.
Here is the description from the code list, in my User's Guide

Code
128 Component-specific Parameter (used to request para-
meter data transmissions from a specific component on the
datalink)

Drive Safely
Joe