Not to hijack anything here but since he runs an 03, as do I, wanted some input as well on the whole EGR unplugged theory.
I don't have any codes, and I don't have any issues with the fan not running the way it should. I'm deleted, no cooler or EGR.

I've read threads about this not being an issue with many owners on the early builds, just wanted some more input on this.

 

Looks like my new friend Watson has narrowed this down by identifying the 'chewed up mess' of a wiring harness that seems to go everywhere around that engine. I've been fiddling more with it and have the engine running smoothly now with the EGR wires plugged in. So, there must be a short in there after all. How big of a job would it be to replace that whole electrical mess once and for all? Is it one part, or a bunch?

 

Glad I could be of assistance.
Wiring harness is about $700US and not to bad of a job, about a days worth for a rookie. OR, go slow, separate that pile of headache and apply some electricians tape in the right spot followed by a little liquid electrician's tape to hold everything solid at the repair site.

Ask your mechanic why he felt the need to unplug that sensor... you'd like to know what issues he fixed or suspected by doing that.

Your near Kamloops... pretty country!

Mike,
Sure your not confusing EBP and EGR?

 

Nope, EGR is gone, nothing plugged in there and it's blocked off with a plate, NADA. I have yet to see anything odd with the cooling fan. Granted it's not exactly cooling fan weather here right now, but I bought this truck back late July and it had plenty of opportunity to overheat from lack of cooling fan.

I have read countless threads of others with early builds that swear it did not affect fan operation, but I wonder if a tuner makes a difference? This truck has an SCT emblem inside the cab(one of those freebies they give you) but did not come with a tuner. I wonder if it's still got some kind of tune in the PCM, but I doubt it, although it does shift crisply..........I attribute that to the early builds being known for this attribute as well, also read in other threads.

The EBP on the other hand, has be double dog confused now. A few months back I was told early builds don't actually use the EBP for turbo action since it came from other sensors, then I was told early build EBP does in fact affect turbo operation to a good degree. So which is it? Is this inferred on early builds or not?

 

I'm pretty sure EBP is inferred, not EGR and it will set a soft code. Have you watched fan speed on the scan gauge? it's FSS for the x-gauge. Mine has only gone above 1200rpm once and I run a 200* stat, pull a 25' trailer with quad in back, July heat in VA is HOT and never saw anything above 217*.. and that was at 70mph.. up rolling grades, 4 people in the truck and all our camping junk... even a good 1/4 cord wood for marshmallows at night.

I have a soft code for EGR always set, P0401 but no CEL... which my tuner is supposed to do.

 

I will plug that one in the SG tonight, good info. I don't have that PID up, but will make note of this when it starts to warm up. It's possible the truck has not needed that much cooling up to this point.
PO towed things during summer months as well, came from twin cities area, they are no stranger to heat but again, don't know that he towed anything heavy.

 

Mike,
I'd say outside temps have less to do with engine temps than you'd believe... it's just a point to start from and always ends at t-stat open... that simple. If it's 40* outside, it goes up until the t-stat says open. If its 85* outside.... it goes up until t-stat says open. It just doesn't have as far to get there.

If everything works correctly, the trucks temp shouldn't fluctuate much. As load increases, t-stat opens and fan cools circulated water... the hotter it gets the more open the t-stat gets and fan increases. Temps fall, t-stat closes, fan drops RPM and water flow decreases... at some point its responding to slight differences in engine temp... a little more fan and faster water flow, all centered around the T-stat.

And the EGR trigger of hotter air, until that's disconnected. Your tuner tells it to use these per-programmed parameters they give it to use... well I'm pretty sure it does (a tuner would know, trade secrets).