Ok guys here's one for the mechanics on here. I have a 2004 3/4 ton Chevrolet with a 6.0, I will be driving and you will feel a thump and the truck will go into "reduce power" mode. The temperature is normal, it doesn't matter if I have a full tank of fuel or empty. Anyone run into this?

You need to check the codes...I'm assuming this is electronic throttle body.

Yes it is electronic throttle body, but the check engine light isn't on.

There will still be a code stored if the reduced engine power light came on! Most likely cause will be a throttle body and a wiring connector at the t-body, but there are other things that cause this!

A can of throttle body cleaner is about $5 and the gasket is about another $5. That would be my first guess if I was going to throw parts/money at the problem instead of paying a dealer $100+ to diagnose it.

My 2004 Silverado 1500 with the 5.3L just ran into a similar issue about a year ago and I had to clean the throttle body. About a half hour's worth of work total.

Check the codes. And do like patriot07 said. go from there.But warning...on gm vehicles sometimes when you unplug the throttle body it will need to be re calibrated and when you crank it up it will want to run wide open. You can remove the the throttle body from the intake and clean it with out unplugging the wire harnesses from it.Yea its a *#*## but it can be done. I recommend Berymanns.

no need to remove, just clean it on the truck. prob a tps issue in TB or a wiring problem.

hey there not sure if the problem is still there. But in 2003-2006 silverado there was a service bulletin for this malfunction.
What the fix is there is a problem in the connector at the throttle body so u are receiving a throttle correlation code.
It will not always throw the MIL on. So what needs to happen is

#1 disconnect battery
#2 locate and remove throttle body connector
#3 look at plug female and male side for dmg pins or noticeable debris
#4 take q-tip with rubbing alcohol and clean pins male and female
thoroughly make note not to dmg or bend. Spray brake clean or electric cleaner into connector and on throttle body side
air dry then plug in.
#5 reconnect battery clear codes check operation
#6 if problem is not resolved do same steps on throttle pedal stepper motor


if this does not help check for debris on throttle blade and or underneath pedal assembly
but there is NO CALIBRATION for this...or will u need to get it calibrated. Also it will not run wide open like a toyota lol

give me a shout if u need help im in dfw area. ASE mechanic
NICHOLAS KISSAM