Reduced power mode

Typically, what triggers the system to go into limp home(reduced power) is a fault that relates to the throttle actuator or accelerator pedal position assembly. Ideally, you should seek the trouble code that is associated with it. One crucial concern, is does it have any aftermarket stuff installed? There may be a bulletin that states(depending on the code) the throttle body or body connector could be cause, and it could be. I have seen instances where this was followed, only to have the fault reoccur, and it eventually was ruled to aftermarket installations into critical circuits. The electronic throttle is run on 5 volt potential, so some resistance that would go unnoticed in a 12 volt circuit, causes intermittent problems in a 5 volt circuit.

The P0171 is a lean code for one bank of cylinders. It would not result in a reduced power message. I would clear it and see if it returns over time. The P1516 will result in reduced power. There is a bulletin I included for reference, may or may not apply, but gives a starting point.

#PIP3089B: SES Light And Reduced Engine Power DTC P0120 P0220 P1516 P2135 - keywords accelerator actuator APP blade body connector connection DTC L33 L59 LH6 LR4 LM7 LS1 LS2 LQ4 LQ9 module position reduce sensor - (Oct 31, 2006)

Subject: SES Light and Reduced Engine Power DTC P0120 P0220 P1516 P2135

Models: 2004-2006 Buick Rainer

2005-2006 Cadillac CTS-V

2003-2006 Cadillac Escalade

2003-2006 Chevrolet Avalanche, Corvette, Express, Monte Carlo, Silverado, SSR, Suburban, Tahoe, Trailblazer

2003-2006 GMC Envoy, Savana, Sierra, Yukon

2003-2006 Hummer H2

2005-2006 Pontiac GTO

Equipped with a 4.8 5.3 6.0 or 7.0 V-8 Engine

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
A vehicle may be brought into the dealer for a reduced power message, and DTCs P0120, P0220, P1516, P2101, or P2135.

The Throttle Actuator Control (TAC) / throttle body type trouble codes, may be caused by a loose wiring crimp at the throttle body connector, or a broken throttle body circuit.

Recommendation/Instructions:
Complete the current SI diagnostics for any symptoms or trouble codes found. If a intermittent T/P or TAC module type code is occurring complete the inspections below.

Inspect all related throttle body terminals for a loose wiring crimp. The loose crimp may be difficult to find, and the poor connection will be between the terminal and the copper strands of the wire. Wiggle test the individual throttle body circuits to see if the concern can be duplicated.
Inspect the related circuits for broken wires inside the insulation. The outer wire insulation may look fine, but the internal copper strands may be partially broken. Breaks in the wires usually occur within 1 to 4 inches of the throttle body connector. Wiggle testing may also induce a trouble code to set.
On C/K trucks complete SI procedures for voltage drop on grounds G103 and G104. Grounds G103 or G104 may be loose or corroded.
If a terminal crimp or a broken wire has been found, repair or replace only the circuits involved. There is a throttle body pigtail connector available through GMSPO, but installing this pigtail connector may cause other intermittent TAC module/TP codes at a later date. If this pigtail must be used, please follow the SI procedures for Splicing Copper Wire Using Splice Sleeves. (The proper Kent-Moore crimping tool must be used for this repair).

The test chart for that code involves some circuit testing, and may be most streamlined with a scan tool that can display data. Often times this code can be hard to duplicate. If I were to start somewhere, it would be splicing a new connector at the throttle body.

Thanks for the heads up Chief_FI.

Flyboy did you ever get this diagnosed and fixed, or do we need to do more testing and diagnosing?

Please post your question here

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Cheers, Ken

Did you check coolant level?

Check your ect sensor might be part of problem and check for broken wire
at throttle body and firewall it rubs on there and wears through. It'a blue and white wire. You may need to replace the throttle body as well which is pricey. Also check the ground wire at back of lh head and give a tug the eyelet likes to break there just a soft tug will do it.

On chart in pic one side is temp and other is ohms so check it that way lh side is temp. See pic for other app is the gas pedal

The crimp style connectors should never be used on vehicles now a days. You should only use solder type connections with shrink tube to protect them. Glad you found the problem.

Tht is the throttle control module-gas pedal in laymens terms. Check battery for condition as this can cause it also do a load test. Tire stores auto parts do for free. Then see if terminal ends are corroded on gaspedal if you are in the winter climates. You shold also get it scanned first too to see if other codes are set as they may set this one. Finally check gas peadal to see if it is shorted out or not sending correct voltage to pcm.