GM Service Manual Online
For 1990-2009 cars only

Aftermarket Accessories

Do not connect aftermarket accessories into the SIR circuits. All such circuits are indicated on circuit diagrams with the SIR symbol.

Do not connect aftermarket accessories into the 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.

Some possible causes of vehicle problems related to aftermarket accessories include:

    • Power feeds connected to points other than the battery
    • Antenna location
    • Transceiver wiring located too close to vehicle electronic modules or wiring.
    • Poor shielding or poor connectors on antenna feed line
    • Check for recent service bulletins detailing installation guidelines for aftermarket accessories