C 3500 Truck 2WD V8-6.0L VIN U (2001)
Information Bus: Symptom Related Diagnostic Procedures
Scan Tool Does Not Communicate With Class 2 Device
CIRCUIT DESCRIPTION
Modules connected to the class 2 serial data circuit (some are optional) monitor for serial data communications during normal vehicle operation.
Operating information and commands are exchanged among the modules. Connecting a scan tool to the DLC allows communication with the modules
for diagnostic purposes. Diagnostic Trouble Codes (DTCs) may be set due to this symptom and during this diagnostic procedure. Complete the
diagnostic procedure in order to ensure all the DTCs are diagnosed and cleared from memory.
DIAGNOSTIC AIDS
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The BCM detects that the ignition is ON and sends the appropriate power mode message to the other modules. Therefore, the BCM must be
connected to the DLC for any other module to communicate with the scan tool.
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When the class 2 serial data circuit is shorted to ground, U1300 will be set. Refer to DTC U1300. See: Testing and Inspection/Diagnostic Trouble
Code Tests and Associated Procedures/U Code Charts/U1300
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When the class 2 serial data circuit is shorted to B+, U1301 will be set. Refer to DTC U1301. See: Testing and Inspection/Diagnostic Trouble
Code Tests and Associated Procedures/U Code Charts/U1301
TEST DESCRIPTION
