Hey chevy fans im posting this for a friend with a 01 3500 that is having the reduced power light or alarm come on every couple weeks. He has replaced the fuel filter twice in the past couple weeks because it has no power and comes in spurts sometimes it runs fine and sometimes it will fall on its face, it ran fine tonight with the light on but would not down shift. truck has about 240k on the clock and any help would be greatly appreciated. Thanks in advance as i am a cummins guy and don't know much about the dmax

 

Limp mode. There is an issue somewhere with the trans