Reduced power mode

Send us the code so we can investigate further. This may need a pro to look at it however. There is a TSB on this maybe for yours vehicle, see if the fuel injector harness has rubbed through on back of alternator. If it has this may be your problem and best ix is to repair the wires and install new conduit. You will need to remove the electrical connectors in pic.

Also check these locations for chaffed wires these are known trouble spots, and can lead to the damage of control modules...
Page 1 of 3 No Communication with Any Modules, Memory Seat May Not Recall, Multiple U-DTCs ...
No Communication with Any Modules, Memory Seat May Not Recall, Multiple U-DTCs Set or Instrument Panel Cluster (IPC) Warning Indicators, Crank No Start (Inspect/Repair Affected Wiring Harness) TECHNICAL SERVICE BULLETIN Reference Number(s): 03-08-50-014A, Â Date of Issue: Â January 20, 2006 2003-2006 Cadillac Escalade, Escalade ESV, Escalade EXT; 2003-2006 Chevrolet Avalanche, Silverado, Suburban, Tahoe; 2003-2006 GMC Sierra, Yukon, Yukon XL; with Front, Individual (Non-Bkt) Seat (RPO AN3) and/or Active Brake Control (Stabilitrak(R)) (RPO JL4) This bulletin is being revised to update the various conditions and add the 2004-2006 model years, additional diagnostic and warranty information. Please discard Corporate Bulletin Number 03-08-50-014 (Section 08 - Body & Accessories). Related Ref Number(s): 03-08-50-014A Affected Model(s): Supercedes:
ARTICLE BEGINNING
CONDITION
Some customers may comment on any of the following conditions:
Various IPC Warning indicators are coming on. "Â Driver Information Center (DIC) displays "Unknown Driver". "Â Memory seat may not recall. "Â RKE fobs may be inoperative. "Â Radio or HVAC may shut off. "Â Engine cranks but will not start. "Â
Upon investigation, the Technician may find multiple U-DTCs set.
10/7/2010
Page 2 of 3 No Communication with Any Modules, Memory Seat May Not Recall, Multiple U-DTCs ...
CAUSE
Fig. 1: Possible Pinch/Chafe Location Courtesy of GENERAL MOTORS CORP.
On RPO AN3 equipped vehicles, a chafed or pinched seat wiring harness under the driver seat may be a cause of this condition. Because of the routing, a portion of the seat wiring harness may rest on the inboard edge of the seat track or frame. Over time, the harness may be pinched or chafed because of the seat movement. Refer to the above illustration. The illustration shows the inverted position of the seat bottom. The arrow shows the primary location of the possible harness chafing/pinching.
Also, on any of the above listed vehicles, the PCM wiring harness may be chafing against the precharge pump bracket (Refer to Document ID# 1252958) or the battery tray.
CORRECTION
On RPO AN3 vehicles, inspect the routing of the seat wiring harness. Reroute the seat wiring harness and attaching harness fastener (1) to the opposite side of the seat module bracket. Repair the harness as necessary. Refer to Wiring Repairs in the Wiring Systems sub-section of SI. The seat may have to be removed for ease of access and proper repair of the wiring harness.
Inspect the routing of the PCM wiring harness at the precharge pump bracket and the battery tray. Repair the harness as necessary. Refer to Wiring Repairs in the Wiring Systems sub-section of SI.
Page 3 of 3 No Communication with Any Modules, Memory Seat May Not Recall, Multiple U-DTCs ...
If any of the above conditions still remain after this repair, refer to SI for further diagnostic information.
WARRANTY INFORMATION
For vehicles repaired under warranty, use:
Warranty Information
Labor OperationDescriptionLabor Time N9542 Wiring and/or Connector - Seat System and/or PCM - Repair 0.2-0.4 hr

Did you check for chafed wires yet? You may need to open the conduit to see the wires inside looking for bare wires.

That is a problem with the controls for the throttle actuator in the "drive by wire" system. It's a pretty complicated diagnosis that will likely require a professional scan tool to diagnose correctly.

If they have to fix the computer is it because they can't read it? A lot of these limp modes are shorts in trans wiring from trans to pcm. You need to see what code it is first. Maybe the mechanic shold do a freeze frame and check things like that to get an idea of what's happening or maybe that has been done.

Then they have to fix the connection or why it's not getting power to reader and won't read first then they can scan it and find out why it's in limp mode.

Tmay only be one to fix it and scan it

You can disconnect the battery to reset the pcm, but you need to find out why its going into limp mode. Any trouble codes?

There is a fault within the electronic throttle, or possibly traction control. The slowing is a limp-home mode. This type of fault will have fault codes associated with it. As far as what it could be, the possibilities are many. If you can obtain the fault codes, it could narrow it down. A code reader, or scan tool is necessary.

I don't know where you got that definition from but it doesn't apply to your vehicle. The definition on yours is. "Throttle Actuator Control Module serial data circuit"
Your truck has a "drive by wire" system with all electronic throttle controls and there is a problem with communication in the system. This is not going to be a DIY type job as it will require some special equipment to diagnose it properly.

Check to see if your battery is any good as well as your grounds. That is one of the things that will set this off. As you have a 2003 and its 'the original battery it's on borrowed time. But also make sure your charging system is up to snuff as well. That is your lTAC module that is givin g you troble or throttle actuator control module.

You're welcome. Let me know what you find.

Joe

Why do you think it is the converters and O2 sensors? Unless the converters are plugged they normally will not effect engine power. The O2 sensors very seldom cause reduced power output either. What were the exact codes you had, and what were/are the symptoms?