Do not connect aftermarket accessories into the following circuits:
Warning: Refer to SIR Warning in the Preface section.
|     •  | SIR circuits, all such circuits are indicated on circuit diagrams with the SIR symbol.  | 
 
Caution: Refer to OBDII Symbol Description Caution in the Preface section.
|     •  | 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:
|     •  | Power feeds connected to points other than the battery | 
 
|     •  | 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. |