Something wrong with the throttle actuator control system, which will need further diagnosis to determine which component in the system is defective, or which wiring is corrupted.
One known problem (but not necessarily your problem) is:
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.
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)