Testing the Serial Data Circuits for a Short between the Circuits

Vehicle OFF, all access doors closed, all vehicle systems OFF and all keys at least 3 meters (9.8 feet) away from vehicle. It may take up to 2 minutes for all vehicle systems to power down.
Disconnect the harness connectors with the powertrain high speed GMLAN serial data circuits at an easily accessible device that is not communicating.
Test for greater than 110 Ω between each pair of serial data circuits at the device connector that was just disconnected.
- If each pair of serial data circuits is 110 Ω or greater
  Replace the device that was disconnected.
- If any pair of serial data circuits is less than 110 Ω
Connect the harness connectors at the device that was disconnected.
Disconnect the harness connectors with the powertrain high speed GMLAN serial data circuits at another device, in the direction of the circuit shorted together.
Test for greater than 110 Ω between each pair of serial data circuits at the device connector that was just disconnected.
- If each pair of serial data circuits is 110 Ω or greater
  Replace the device that was disconnected.
- If any pair of serial data circuits is less than 110 Ω
Repeat step 4 until one of the following conditions are isolated:
- Serial data circuits shorted together between two devices or splice packs, if equipped.
- Serial data circuits shorted together between a device and a terminating resistor.
- Serial data circuits shorted together between the X84B auxiliary data connector and the first device or splice pack.
- A shorted terminating resistor.