CTS V8-5.7L VIN P (2004)
Information Bus: Symptom Related Diagnostic Procedures
Scan Tool Does Not Communicate With High Speed GMLAN Device
SCAN TOOL DOES NOT COMMUNICATE WITH HIGH SPEED GMLAN DEVICE
Modules connected to the high speed GMLAN serial data circuits monitor for serial data communications on the high speed GMLAN network during
normal vehicle operation. Operating information and commands are exchanged among the modules. When a module detects a bus-off condition a DTC
U0001 or U2100 will be set. These DTCs can be retrieved as history only.
Diagnostic Aids
The engine will not start when there is a total malfunction of the high speed GMLAN serial data circuits while the engine is not running. The following
conditions may cause a total loss of high speed GMLAN data communication:
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A short between high speed GMLAN (+) and high speed GMLAN (-) circuits
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Any of the high speed GMLAN serial data circuits shorted to ground or voltage
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A module internal malfunction that causes a short to voltage or ground on the high speed GMLAN circuits
Test Description
Steps 1 - 2