Radio Frequency Interference and Vehicle Security

An intermittent no crank or start-stall condition with the security light illuminated on some 2008-2012 Enclave; 2010-2012 LaCrosse; 2012 Verano, Regal; 2008-2012 CTS; 2007-2011 DTS, STS; 2011-2012 Cruze; 2012 Sonic; 2009-2012 Traverse; 2007-2012 Acadia; and 2007-2010 Outlook models may be due to Radio Frequency Interference (RFI) with the vehicle security system.


DTCs B3055 (No Transponder Modulation or No Transponder), B3060 (Unprogrammed Transponder Identification Code Received), and/or B3935 (Transponder Authentication Error) may be set in history. In most cases, the condition cannot be duplicated.


On vehicles equipped with Passive Entry/Passive Start (RPOs ATH, BTH), it is also possible the vehicle may have a condition where the passive entry is inoperative and/or there is a No Fob Detected message, but the vehicle will start with the key fob placed in the fob pocket.


Do not replace any parts for this condition prior to duplicating the condition.


With the advancements in today’s technology, there has been a great increase in the number of Radio Frequency Identification Devices (RFID) found across many communities, businesses, and automobiles. It is possible that another RFID device may interfere with the Passkey system. The range of the interference can vary based on the strength of the RFID, which may affect the key-to-exciter module communication. The most common devices found are: vehicle immobilizer keys from other vehicles, keyless access transmitters from other vehicles, highway/bridge toll passes, gate passes, community/parking access cards, fuel station speed passes, and building access swipe cards/transponder devices. (Fig. 6)


Fig 6


In addition, verify the vehicle owner is not inducing the concern by flipping the key while cranking the engine. Refer to #PIT5030 for more information.


For vehicles with Passive Entry/Passive Start, it is possible to get RFI from transponders or other frequency-emitting devices in the area. An aftermarket RFI meter can be used as an aid to locate the stray RFI signals. (Fig. 7)


Fig 7


TIP: Direct owners to the appropriate section in their Owner Manuals for information about how a device complies with Part 15 of the FCC Rules. Examples of where this information may be found depends on the model and/or year, but in most manuals, refer to the Immobilizer Operation, Keyless Entry, Keyless Access, or Radio Frequency Statement sections.


– Thanks to Ernest Haller



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