I wanna know why is my security light still coming on after i jus spent 671.00 on a bcm and the light didnt come on yesterday but today its right bck on it stopped while i was driving and went dead
CAR WENT DEAD JUST HAD A BCM PUT ON YESERDAY MODEL 03 IMPALA AND SECURITY LIGHT IS ON AND WILL NOT GO OFF
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Battery voltage from the CHMSL/BCK-UP fuse located in the rear fuse block is supplied to the body control module (BCM) for backup lamp operation. When the gear selector is placed in to the REVERSE position, the powertrain control module (PCM) sends a GMLAN serial data message to the BCM indicating that the gear selector is in the reverse position. The BCM then applies battery voltage to the backup lamp supply voltage circuit illuminating the left and right backup lamps. Ground for both backup lamps is provided at G403.
Hard to say why the light comes on , may have a diagnostic trouble code stored in the BCM - body control module ! Do you have a bunch of other key's on the same ring as the vehicle key ?
Passlockâ„¢ System
The theft deterrent system has been incorporated into the body control module (BCM). The theft deterrent system prevents the vehicle operation if the correct key is not used in order to start the vehicle. The ignition key turns the ignition lock cylinder. The cylinder rotation produces an analog voltage code in the Passlockâ„¢ sensor. This voltage code is received by the BCM. The BCM compares the voltage code to the previously learned voltage code. If the codes match, a class 2 message is sent from the BCM to the powertrain control module (PCM). The message enables the fuel injectors and the crank relay.
The design of the Passlockâ„¢ system is to prevent vehicle theft by disabling the engine unless the ignition lock cylinder rotates properly by engaging the correct ignition key. The system is similar in concept to the passkey system. However, the Passlockâ„¢ system eliminates the need for a key mounted resistor pellet. The components of the Passlockâ„¢ system are as follows:
• The ignition lock cylinder
• The ignition switch
• The Passlock™ sensor
• The body control module (BCM)
• The SECURITY indicator
• The powertrain control module (PCM)
When anyone of these codes set the BCM will turn on the SECURITY light !
DTC B2947
DTC B2948
DTC B2957
DTC B2958
DTC B2960
DTC B3031
DTC B3033
DTC P1626
DTC P1629
DTC P1630
DTC P1631
Your best bet , take it to a qualified repair shop an have it checked !Here are some reasons for the light to come on .
Conditions for Setting the DTC
The BCM detects a short to ground on the Passlock sensor power circuit for 1 second, with the ignition switch in the ACCESSORY, ON, or START position.
The PCM has detected a loss of the state of health serial data message from the theft deterrent system.
sounds like the bcm may have failed, if so new bcm and new keys and programming with tech2
thats the worst case
or
wiring issue eg ignition switch
its not reading the key due to security light still flashing
the manual over ride should have worked if it didnt then i would be checking all fuses and power inputs to the bcm from the ignition switch
The communication between the key, the ignition lock cylinder and the BCM or TDM is key to the antitheft system working correctly. If there is any break or miscommunication for even a second, the security light will come on and possibly disable your vehicle. All too often when the security light is addressed, the first thought is to change out the igniton when more often than not the BCM or TDM computer is the problem. I have found that while fixing the system is ideal, bypassing the system is more cost effective and permanent. This system is known to fail and fixing a failed system is pointless in my eyes. Here is a link that explains the system and offers solutions that you can perform to fix this yourself
this problem is a bad BCM the relay is part of the computer system and your problem is common. replace the BCM and reprogram security and you will be good to go.
Or find someone to replace the relays inside. Harder to do than you think, I change them all the ime, but not easy to find the replacements.
Go to the very front (or back) of your owners manual (NOT in the radio section) and you may find the codes there. If not, go to your GM dealer. (Should be inexpensive job.)
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