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Home >> Chevrolet >> 2002 >> C3500 HD 8.1 G, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 8.1L >> Diagnostic Information and Procedures >> DTC P1221 >> Test Description
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Test Description

The number below refers to the step number on the diagnostic table.

  1. 21. When the TAC module detects a condition within the TAC system, more than one TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual condition may correct more than one DTC. Disconnecting components during testing may set additional DTCs. Keep this in mind when reviewing the stored information, Capture Info.
Fig 1: DTC P1221 (1 Of 2)
G01599088Courtesy of GENERAL MOTORS CORP.
Fig 2: DTC P1221 (2 Of 2)
G01599089Courtesy of GENERAL MOTORS CORP.
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