Checking Aftermarket Accessories
Warning: Refer to SIR Warning in the Preface section.
Caution: The OBD II symbol is used on the circuit diagrams in order to alert the technician that the circuit is essential for proper OBD II emission control circuit operation. Any circuit which fails and causes the malfunction indicator lamp (MIL) to turn ON, or causes emissions-related component damage, is identified as an OBD II circuit.
Do not connect aftermarket accessories into the following circuits:
| • | SIR circuits, all such circuits are indicated on circuit diagrams with the SIR symbol. |
| • | 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 aerial feed line |
| • | Check for recent service bulletins detailing installation guidelines for aftermarket accessories. |
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