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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1057 (Engine Controls And Fuel - 6.6L - DTC P1224 To DTC P2463) >> DTC P2122, P2123, P2127, P2128, or P2138 >> Component Testing

Component Testing

WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT: You must perform the Circuit/System Testing to verify the integrity of the APP circuits before proceeding with the Component Testing.
  1. Ignition OFF, install a 3A fused jumper wire between the 5-volt reference circuit terminal of the affected APP sensor and 5 volts.
  2. Install a jumper wire between the low reference circuit terminal and a ground.
  3. Install a jumper wire at the signal circuit terminal of the affected sensor.
  4. Ignition ON, sweep the sensor through the entire range while monitoring the voltage between the signal terminal jumper wire and the low reference terminal with a DMM. The voltage should vary between 0.80-4.75 volts for APP sensor 1 and 0.30-2.50 volts for APP sensor 2 without any spikes or dropouts.
    • If the voltage is not within the specified range or is erratic, replace the APP sensor assembly.
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