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GMC Forum: 2003 GMC Envoy code P0220. The service engine light came and "Reduced Engine
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Old 12-15-2009, 09:44 AM
ronbest9454 ronbest9454 is offline
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Default 2003 GMC Envoy code P0220. The service engine light came and "Reduced Engine

Performance"? My wife was driving and the service engine light came on but she did not notice and drivability problems. I scannned it and came up with code P0220 throttle / pedal position sensor /Sw B-CKT Malfunction. Would should I check or what would cause this code to come up? Any help would be appreciated.
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Old 12-15-2009, 02:07 PM
Molson02536 Molson02536 is offline
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P0220....Throttle/Pedal Position Sensor/Switch 'B' Circuit


A growing number of late model cars and trucks have no throttle cable. A small electric motor is used to operate the throttle using inputs from position sensors on the gas pedal. When the gas pedal is depressed, the electrical resistance of the potentiometers inside the pedal sensors change. The control module notes the change in position and commands the throttle to open. A pair of throttle position sensors on the throttle shaft note the change in throttle position and provide feedback signals to the control module so the module knows the exact position of the throttle and that everything is working correctly.

Throttle position sensors typically experience the most wear in the position just above idle, since this is the throttle's position for most driving. A worn sensor may cause a skip or drop in the reading when the throttle opens, causing a momentary loss of input to the PCM. The result is usually a hesitation or stumble because the PCM fails to provide the necessary fuel enrichment.

If the TPS mounting is loose, it will produce an erratic signal leading the ECM to believe the throttle is opening and closing. The result can be an unstable idle and intermittent hesitation. If the TPS is shorted, the computer will receive the equivalent of a wide open throttle signal all the time. This will make the fuel mixture run rich and set a fault code that corresponds to a voltage signal that's too high. If the TPS is open, the computer will think the throttle is closed all the time. The resulting fuel mixture will be too lean and a fault code that corresponds to a voltage signal that's too low will be set.

Here are some information that will help you. From what I have seen the likely cause is the t/b connector and the grounds behind both heads.

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.

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) Good luck and hope this helps.
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