Starting in limp mode

[Masterblaster]

Hello fellow LB7 owners,

I have an 03 2500HD with 266K that is starting in limp mode. Batteries and alternator are new and tested. CP3 pump has pressure. Fass pump is working and is a little over a year old. Every morning when I go to start it will start in limp mode. If I shut her off, open and close the door, a lock it, wait for the dome lights to dim, unlock it and act like I’m getting back in and start she fires up normal (most of the time). Thought the fuse box was corroded but it’s nice and clean underneath. Has anyone ever experienced this? I’m at my wits end with this. When she starts she runs perfectly. No loss of power, no smoke. It’s strange

 

[2004LB7]

Welcome

Limp mode will always have a code associated with it unless it's been tuned and codes turned off without dealing with the reason for limp

Get us a code and we can help you. There is at least a dozen reasons it can go into limp mode. So we need the code

 

[Masterblaster]

I bought the truck from a dealer and it has the “Attitude” tuner on it. I’ve had the truck for 3 years and never had an issue. I set the tune for “mileage” because diesel was $7 per gallon. I’ve had shops and auto zone plug scan tools in and no codes were found. Should I disconnect the tune and see if she throws a code or try something else?

 

[TheBac]

Yes. First thing to do is unplug the Edge module. Those underhood boxes do have a lifespan and they do fail.

 

[mojito5000]

Yes. First thing to do is unplug the Edge module. Those underhood boxes do have a lifespan and they do fail.

100% this. I had a whole slew of problems with my truck, random cut off's, no starts, etc. Once I removed the whole edge juice setup, everything went back to normal. And to tell you the truth, millage was about the same from the eco mode on the edge.