Testing the Serial Data Circuits for a Short between the Circuits
WARNING: This page is about a different car, the 2011 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the harness connectors with the high speed GMLAN serial data circuits at an easily accessible control module that is not communicating.
- Ignition OFF and all vehicle systems OFF, key out of the ignition switch, all access doors closed. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 35 Ω between each pair of serial data circuits at the control module connector that was just disconnected. Verify that one pair of serial data circuits are less than 35 Ω.
- If each pair of serial data circuits is greater than the specified range, replace the control module that was disconnected.
- Connect the harness connectors at the control module that was disconnected.
- Disconnect the harness connectors with the high speed GMLAN serial data circuits at another control module, in the direction of the circuits shorted together.
- Ignition OFF and all vehicle systems OFF, key out of the ignition switch, all access doors closed. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 35 Ω between each pair of serial data circuits at the control module connector that was just disconnected. Verify that one pair of serial data circuits are less than 35 Ω.
- If each pair of serial data circuits is within the specified range, replace the control module that was just disconnected.
- Repeat step 3 until one of the following conditions are isolated:
- Serial data circuits shorted together between 2 control modules or splice packs, if equipped
- Serial data circuits shorted together between a control module and a terminating resistor
- A shorted terminating resistor