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Circuit/System 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.
  1. Test for less than 1 ohm between the DLC ground circuit terminal 5 and ground.
    • If greater than the specified range, test the ground circuit for open/high resistance.
  2. Ignition OFF, disconnect the harness connector at splice pack JX 221.
  3. Ignition ON, with a scan tool, attempt to communicate with the instrument panel cluster (IPC). Communication should be available.
    • If no communication, disconnect the modules still connected to the DLC one at a time, starting with the furthest from the DLC and attempt to communicate after each disconnect. When communication occurs, test the serial data circuit for a short to ground and a short to voltage between the last module disconnected and the previous module disconnected. If the circuit tests normal, replace the last module disconnected. If no communication is possible, test the serial data circuit for a short to ground, a short to voltage or an open/high resistance between the last module disconnected and the DLC. If the circuit tests normal, replace the last module disconnected.
  4. Install a 3-amp fused jumper wire between terminal A and terminal M of the splice pack. Install another 3-amp fused jumper wire to terminal L.
  5. Using the open end of the jumper wire at terminal L, connect to splice pack terminals B through K and attempt to establish communications with each module connected to the splice pack, one at a time. Each module should be able to communicate.
    • If communications cannot be established with any module after connecting an individual module, replace the module that caused the no communication.
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