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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 148 (Automatic Transmission - 6L50/6L80/6L90 - DTC P0989 To DTC P2764) >> DTC P0989 or P0990 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2007 GMC Yukon XL, 2007 GMC Yukon, 2007 Cadillac Escalade EXT, 2007 Cadillac Escalade ESV, and 2007 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ensure the TFT is near the temperature displayed in the Failure Records.
  2. Start the engine and place the transmission range selector in D6.
  3. Observe the TFP Switch 5 parameter while commanding 1st gear and then commanding 2nd gear with the scan tool. The TFP switch 5 should transition from low in 1st gear to high in 2nd gear.