No Fob Detected Message

Some 2021 Tahoe, Suburban, Yukon and Escalade models may have a no crank/no start condition with a No Fob Detected message on the Driver Information Center. The Remote Keyless Entry (RKE) transmitter, or key fob, also is not detected when placed in the backup pocket in the center console.

If this condition is present, the key fobs (Fig. 11) will work manually (with a button press), but not passively (detected by the vehicle). No current passive antenna or immobilizer DTCs will be set in the Body Control Module (BCM).

 

Fig. 11

 

In addition, the vehicle will have a battery state of charge above 12 volts, but it will not power mode to the Run or Accessory position. As a result, the transmission cannot be shifted from Park. The parking brake also may be engaged and cannot be released.

These conditions may be due to an internal BCM fault that causes the key fobs to not be recognized and a loss of the immobilizer.

Perform the following diagnostic steps if these conditions are found:

  1. Verify that the active RKE functions are working for all transmitters (example: Locking/Unlocking/Alarm/Liftgate and Remote Start).
  2. Verify all passive RKE functions are inoperative for both transmitters.
  3. Verify Low Frequency (LF) “Passive” Antennas are not transmitting by using the EL-52545 TPMS and RF tool.
  4. Verify that the RKE transmitters are not responding to the Passive Challenge with the EL-52545 tool, without pressing any buttons on the transmitters.
  5. Check that the vehicle’s battery state of charge is above 12V.
  6. Verify that there are not any current antenna or immobilizer DTCs set in the BCM.
  7. With both RKE transmitters outside of the vehicle, attempt to change the power mode by pressing the engine start/stop button once every 3 seconds, five times. Check for DTCs in the BCM. There should not be any current antenna or immobilizer DTCs set after performing this step.

 

If all questions can be answered as “yes,” the BCM should be replaced.

Refer to the Keyless Entry System Malfunction documents in the appropriate Service Information for additional diagnostic procedures.

TIP: It may be possible to recover the vehicle from this condition by performing a battery disconnect/reset, allowing the vehicle’s modules to completely power down.

For more information, refer to #PIT5841.

 

– Thanks to Jim Will

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