First of all, my truck is a early 2004 (not an H.O.) and it has a Diablo Sport download in it (towing download).

It has been surging lightly while cruising for the last week or so. Not bad, just enough to notice that the motor is changing speed without moving the throttle pedal.

Today while driving with the cruise control on (70mph), it regestered a fault code and kicked the CC off. The CC doesn't seem to work now.

It has fault code p0602.

Any ideas?

 

My 97 gasser started that slight surging on the highway, ended up being the overdrive in the transmission letting go. Is your automatic? If so, take it out of overdrive and get on the highway and see if it still does it. Just a thought.

 

I'll try that on the way hoome today.

Thanks,

 

p 602 is a programming error

 

It could also be a lift pump going bad. My 2002 did the same thing when the lift pump puked. Surging when cruising. Just a thought.

 

upload your original backup found in the diablo not the stock tune the original backup stock tune and see if this fixes the problem like w.tex iceman said programing error.

 

The fault code went away at the end of the day yesterday. I will go ahead and load the original backup anyway.

As far as the surge goes, I don't know.

the truck has 140,000 on it. The lift pump died at 40,000. the dealer put an updated one on (external).

 

P0602 will be there after you apply the programmer. That is normal.

 

I installed the original backup and the fault code 0602 went away. The surge is still there though. The throttle pedal quit working all together for about 10 seconds yesterday. Now it has code p2121 (throttle position sensor), that makes more sence. Does anyone know of a diagnostic procedure that I should do before I replace the TPS?

 

can you clean it?

brett

 

Ck voltages,5 volt supply and signal if both ok it's time to replace the apps

Bob

 

Well, the dealer wanted $510 for a new TPS. the best deal I found was $485 through Cummins. So I took it out, cleaned it up (even though it was almost spotless already) and put it back together...............................So far (knock on wood) it's working great.

Note: I couldn't find anyone that would sell me just the TPS. You have to buy the bell crank assembly with it. I even tried using the part number that is printed on the TPS at Cummins. No deal.