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Home >> GMC >> 2002 >> C3500 HD 8.1 G, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 8.1L >> Diagnostic Information and Procedures >> DTC P1280 >> Test Description

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. 2. TP sensor 2 and the APP sensor 2 share a common 5-volt reference source. Diagnose DTC P1220 first if DTC P1220 is also set.
  2. 18. This test determines whether or not the TAC module can recognize a change in signal voltage.
  3. 19. There are 3 separate 5-volt reference sources within the TAC module. TP sensor 1 and APP sensor 1 share one 5-volt reference source, TP sensor 2 and APP sensor 2 share another common 5-volt reference source. APP sensor 3 uses the third reference source by itself. This test determines whether the signal circuit is shorted to any one of the 5-volt reference circuits. If a short exists, the corresponding sensor voltage will be pulled low.
  4. 20. The previous step found the signal circuit and a 5-volt reference circuit shorted together. This test isolates whether the short is in the harness or within the TAC module.
  5. 26. 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 P1280 (1 Of 3)
G01599096Courtesy of GENERAL MOTORS CORP.
Fig 2: DTC P1280 (2 Of 3)
G01599097Courtesy of GENERAL MOTORS CORP.
Fig 3: DTC P1280 (3 Of 3)
G01599098Courtesy of GENERAL MOTORS CORP.