MODELS
2007-2023 GM Vehicles
CONCERN
A customer may comment on any of the following complaints:
- Intermittent no crank
- Intermittent no start, or start and stall
- Security / Theft light / Message
- Poor or no RKE range
- Keyless or passive entry/start inoperative
- No Fob Detected message
- Service Tire Pressure Monitor message
- Any of the following DTC’s: B3055, B3060, B3935, C0750, C0755, C0760, C0765, and/or C0775.
On vehicles equipped with keyless/passive start, the vehicle will start if the fob is placed in the fob pocket. In most cases, these concerns cannot be duplicated.
CAUSE
2007-2023 GM vehicles use Radio Frequency (RF) to transmit information. Some aftermarket devices cause Radio Frequency Interference (RFI), which can “jam” the radio frequency being transmitted. Listed below are a number of aftermarket devices that can cause RFI. In many cases, these types of devices will be attached to the customer’s key ring and could be removed from the key ring or from inside the vehicle when the customer drops the vehicle off for service. These items include:
- Vehicle immobilizer keys from other vehicles
- Keyless access transmitters from other vehicles
- Interstate/bridge toll passes
- Gate/door passes to allow access to pools, driveways, entry doors, etc.
- Community/parking access cards
- Fuel station speed passes
- Building access swipe cards/transponder devices
LED lighting can cause intermittent issues when it is turned on. In many cases, when the LED lighting is turned on it can interfere with a RF signal. For example, keyless entry might become inoperative after the first fob button press and aftermarket dome, puddle or other LED lights are turned on.
Some cell phone chargers and devices plugged into the cigarette lighters can cause RFI.
RECOMMENDATIONS
Do not replace any parts for this concern prior to duplicating the concern. Before any in depth diagnosis is performed, question the customer or inspect the vehicle for any types of aftermarket equipment, which could cause RFI. These items need to removed and/or disconnected from the vehicle.
It is possible to get RFI from transponders or other frequency emitting devices in the area. Aftermarket RFI meters/sniffers are available that can be utilized as an aid to locate stray RFI signals. It is important to know what the complaint is and what frequency you are checking. When testing a vehicle for stray RFI signals there are three common frequencies:
- 315 MHz (RKE and TPM frequency)
- 433 MHz (RKE and TPM frequency)
- 125 kHz (Passive entry antennas used on vehicles with passive start/entry)
In some cases, the use of the J43241 Keyless Entry Tester or EL-52545 Tire Pressure Monitor Sensor and RF Diagnostic Tools to scan the vehicle for stray RFI signals has been useful. Remember, while scanning the vehicle you may need to turn on and off electrical devices to see if they are causing the RF interference.
