Express 1/2 Ton Van V6-4.3L VIN W (1999)
Conditions for Clearing the DTC
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A current DTC will clear when a Node Alive message from the failed identification number is detected on the class 2 serial data circuit or at
the end of the current ignition cycle.
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A history DTC will clear upon receipt of a scan tool Clear DTCs command.
Diagnostic Aids
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An intermittent open, short to ground, or short to B+ between the inoperative module and the data line may cause this code to set.
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A poor connection at the inoperative module or the data line may cause this code to set.
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An intermittent open in the data line may cause this code to set.
Test Description
1. A module which loses power during an ignition cycle will cause other module(s) to set Lost Communication DTCs.
2. The malfunction may be due to an open in the class 2 serial data circuit or an open in the module circuit.
6. The module which was not communicating due to an open in the class 2 serial data circuit and may have set Lost Communication DTCs for
those modules that it was monitoring.
8. The modules which can communicate indicate the module which cannot communicate. You must clear the DTC from these modules to avoid
future misdiagnosis.
Scan Tool Does Not Communicate With UART Data Line
Scan Tool Does Not Communicate With UART Data Line
CIRCUIT DESCRIPTION
The UART Serial Data Line is used for communication with the SIR Module. The UART line relies on a 5 volt digital signal for the exchange of
