Replace the battery with a new one if it is depleted. 
	You will need the following items: 
 Replacing the battery 1. Remove the cover. To prevent damage to the key, cover the tip of the screwdriver with a rag. To prevent the buttons from being disassembled, face the button surface downward. 
 2. Remove the module. 
 3. Open the case cover using a coin protected with tape, etc., and remove the depleted battery. Insert a new battery with the "+" terminal facing up. 
 ■Use a CR2016 lithium battery 
 ■If the key battery is depleted The following symptoms may occur: 
 
 
 
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Toyota Tundra Service Manual > Forward Recognition Camera System: Diagnostic Trouble Code Chart
   DIAGNOSTIC TROUBLE CODE CHART Forward Recognition Camera System DTC No. Detection Item Link C1A0A Front Radar Sensor Region Code Mismatch C1A47 Steering Angle Sensor C1AA0 Front Camera Module Circuit C1AA1 FCM Destination Information Unmatched C1AA2 Vehicle Speed Tolerance Malfunction C1AA3 Vehicle  ...