Testing the Serial Data Circuits for a Short to Ground
WARNING: This page is about a different car, the 2010 Cadillac SRX. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the harness connectors with the mid speed GMLAN serial data circuits at an easily accessible control module.
- Ignition OFF for 60 seconds, test for less than 1k Ω between each serial data circuit at the control module connector that was just disconnected and ground. Verify that one or more serial data circuits are less than 1k Ω.
- If all serial data circuits are greater than the specified range, replace the control module that was disconnected.
- Disconnect the harness connectors with the mid speed GMLAN serial data circuits at another control module, in the direction of the circuit shorted to ground.
- Ignition OFF for 60 seconds, test for less than 1k Ω between the serial data circuits at the control module connector that was just disconnected and ground. Verify that one or more serial data circuits are less than 1k Ω.
- If greater than the specified range for all serial data circuits, replace the control module that was just disconnected.
- Repeat step 3 until one of the follow conditions are isolated:
- A short to ground on the serial data circuit between 2 control modules or splice packs, if equipped
- A short to ground on the serial data circuit between a control module and a terminating resistor