When a transmitter authentication is requested, the console passive antenna broadcasts a challenge within the passenger compartment to the transmitter. If the response from the transmitter via radio frequency (RF) is a valid response, the RCDLR determines there is a transmitter within the vehicle. If no response is received, the RCDLR determines that no transmitter is in the vehicle, and NO FOB DETECTED will be displayed on the DIC.

Transmitter authentication occurs during any of the following situation:

The transmitter response for both active and passive functions is received by the external RF antenna located in the back glass. There is a coax that connects the back glass antenna to the RCDLR. If this connection is poor, both active and passive functions could be affected. That is, the customer may notice intermittent NO FOB DETECTED incidents, poor range when remote starting the vehicle, or even issues with the tire pressure monitoring system.

A low transmitter battery or radio frequency (RF) interference from aftermarket devices such as 2-way radios, power inverters, cellular phone chargers, computers, etc. may cause a system malfunction. High RF traffic areas, such as gas stations which use pay-at-the-pump RF transponders, may also cause interference that could lead to a malfunction.

Conditions caused by external influences such are these are considered to be normal. Following this diagnostic will not diagnose an RF interference condition. If RF interference is suspected, question the customer about the conditions or location where the NO FOB DETECTED condition occurs.

Schematic Reference

Remote Function Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Keyless Entry System Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Important: This condition may be caused by low vehicle battery voltage. If the battery is not sufficiently charged (above 10 volts), the system will have difficulties detecting the fob and the NO FOB DETECTED message will be displayed. Correct the low battery voltage condition to eliminate this condition.

1. Verify DTC B3119, B3120, B3121, B3122, or B3123 is not set.

⇒	If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.

2. With the vehicle locked, attempt to passively unlock and enter the vehicle by approaching the vehicle with a valid transmitter and pulling the exterior door handle. The door should unlock and open.

⇒	If unable to enter the vehicle passively, refer to Keyless Entry System Inoperative.

3. Place the transmitter in the console active antenna pocket and attempt to start the vehicle. The vehicle should start.

⇒	If the vehicle does not start, perform the Transmitter Programming procedure.

4. While placing the keyless entry transmitter in various locations within the vehicle interior, attempt to start the vehicle. The NO FOB DETECTED message should not be displayed on the DIC.

⇒

If the message is displayed, inspect for any sources of RF interference such as cell phone chargers, power supplies, etc. that would interrupt transmitter and antenna communication. If inspection does not reveal any items causing RF interference, contact the customer and question the customer about the conditions or location where the NO FOB DETECTED condition occurs. Discuss any devices that are normally kept in the vehicle, such as a laptop or cell phone charger, which may have been removed when the vehicle was brought in for service. It may be necessary to explain to the customer how RF interference degrades the performance of the system.

5. Inspect the external RF antenna connection at the RCDLR. First, gently pull on the coax connector at the module. If the coax comes out, then it wasn’t seated properly. Remove and carefully inspect the coax connection for bent blades or a bent center pin. Fix coax connection if necessary and re-seat connector until a "click" is heard. Gently pull on the coax connection to make sure it is seated properly.

1. Ignition OFF, disconnect the harness connector at the console passive antenna.
2. Install a DMM between the signal circuit terminal A and the low reference circuit terminal B. Set the DMM to capture AC voltage using the MIN MAX function.
3. Attempt to start the vehicle. Verify the DMM captured an AC voltage signal.

⇒	If an AC voltage was not captured, test the signal circuit and the low reference circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the RCDLR.

4. If all circuits test normal, test or replace the console passive antenna.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.