GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 XLR 🢒 Engine 🢒 Engine Electrical 🢒 Key Fob Not Detected

Step

Action

Yes

No

Schematic Reference: Keyless Entry Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle Vehicle DTC Information

2

Important: This condition may be caused by a 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 FOBS DETECTED message will be displayed. Correct the low battery voltage condition to eliminate this condition.

With a valid key fob, attempt to start the vehicle.

Is the NO FOB DETECTED message displayed on the driver information center (DIC)?

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

3
  1. Exit the vehicle with the key fob.
  2. Lock the vehicle.
  3. Attempt to enter both the driver and passenger doors passively with the key fob.

Are you able to enter the vehicle from both doors?

Go to Step 4

Go to Keyless Entry System Inoperative

4

Important: Areas of high radio frequency (RF) traffic may cause an intermittent NO FOB DETECTED message. This is a normal condition. If the vehicle is parked in an area of high RF traffic, move vehicle before continuing with diagnostics.

Move the key fob to various places within the vehicle and attempt to start.

Does the vehicle start?

System OK

Go to Step 5

5
  1. Place the key fob in the limp home pocket located in the glove box with the buttons facing right.
  2. Turn ON the ignition with the engine OFF, by pressing and holding the ACC button for 5 seconds.
  3. Connect a scan tool to the vehicle.
  4. Check vehicle for any DTCs.

Were any DTCs found?

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

Go to Step 6

6

Important: 

   • The voltage signal sent by the remote control door lock receiver (RCDLR) to the passive antenna is a AC voltage signal. The DMM must be set on AC voltage setting to record the voltage pulse to the passive antenna.
   • Use a DMM to record the voltage pulse, using the MIN MAX setting to capture the AC voltage pulse to the passive antenna.
   • The ignition start button must be pressed to produce the voltage pulse to the passive antenna.

  1. Turn OFF the ignition.
  2. Disconnect the keyless entry antenna - back-up.
  3. With the DMM, measure/capture for an AC voltage signal between the keyless entry antenna power circuit and the ground circuit.
  4. Attempt to start the vehicle.

Was an AC voltage signal captured on the DMM?

Go to Step 8

Go to Step 7

7

Test both the keyless entry antenna - back-up power and ground circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 9

8

Inspect for poor connections at the keyless entry antenna - back-up. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 10

9

Inspect for poor connections at the RCDLR. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 11

10

Replace the keyless entry antenna - back-up. Refer to Ignition Lock Key Transmitter Antenna Replacement - Instrument Panel .

Did you complete the replacement?

Go to Step 12

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11

Replace the RCDLR. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 11

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12

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2