Checking Aftermarket Accessories

Do not connect aftermarket accessories into the following circuits:

CAUTION: Refer to SIR Service Precautions Caution in Cautions and Notices.

- SIR circuits, all such circuits are indicated on circuit diagrams with the SIR symbol.

NOTE: Refer to OBDII Symbol Description Notice in Cautions and Notices.

- OBDII circuits, all such circuits are indicated on circuit diagrams with the OBDII 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:
- 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.