Testing the Serial Data Circuits for an Open/High Resistance

Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down.
Disconnect the harness connectors at the gateway isolated low speed GMLAN device that is not communicating and closest to the K56 Serial Data Gateway Module.
Disconnect the harness connectors at the K56 Serial Data Gateway Module.
Test for less than 2 Ω in the gateway isolated low speed GMLAN serial data circuit (circuit number 1102) end to end between the non-communicating device and the K56 Serial Data Gateway Module.
- If 2 Ω or greater
  Repair the open/high resistance in the serial data circuit.
- If less than 2 Ω
Test for less than 2 Ω in the primary low speed GMLAN serial data circuit (circuit number 5060) end to end between the K56 Serial Data Gateway Module and the X84 Data Link Connector terminal 1.
- If 2 Ω or greater
  Repair the open/high resistance in the serial data circuit.
- If less than 2 Ω
Replace the non-communicating device that was disconnected.