Sierra 1500 4WD V8-6.0L VIN U (2006)
Checking Aftermarket Accessories
CHECKING AFTERMARKET ACCESSORIES
Do not connect aftermarket accessories into the following circuits:
CAUTION: Refer to SIR Caution in Service Precautions.
SIR circuits, all such circuits are indicated on circuit diagrams with the SIR symbol.
NOTE: Refer to OBD II Symbol Description Note in Service Precautions.
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OBD II circuits, all such circuits are indicated on circuit diagrams with the OBD II symbol.
Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the
system to verify that these add-on accessories are not the cause of the problems.
Possible causes of vehicle problems related to aftermarket accessories include:
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Power feeds connected to points other than the battery