BCM replacement and Re-learn process - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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OEM Issues Original Equipment Repairs and/or Problems

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  #1  
Old 06-19-2011, 10:32 AM
hpimichael02's Avatar
hpimichael02 hpimichael02 is offline
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2005 Chevy TrailBlazer LS
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BCM replacement and Re-learn process

hey guys,

i gonna get a new BCM i looked at my grounds and they seem fine, so this leaves my BCM- so i noticed that there are color code on the side such as red, green, blue, or in some cases two colors like green and red. and then under taht it has what i think is teh interrior color combo- mine is black and tan ( my inside is also black and tan)

now do i have to get one that matches these colors and interrior codes? or does it not matter ?

so my second question is the re-leran process-
i googled this and only found this site - fullsizechevy.com i think

Quote:
For those vehicles that use a BCM, the BCM can learn the resistance value of the existing key by using the relearn process. In order for the vehicle to start, the BCM (as well as the Passkey module in other vehicles) must identify the resistor pellet in the key, then the BCM sends a password to the PCM. If this password matches the password stored in the PCM, the system enables fuel delivery. So you can see that if either the BCM or PCM are replaced, a relearn procedure is necessary. This same relearn procedure can be used if an ignition key with a different resistance value is used to replace the existing key. Before beginning the relearn, make sure there is a fully charged battery in the vehicle, and both the BCM and PCM are properly powered up and in communication with each other. Now you’re ready to initiate the relearn procedure.

1. First, insert the ignition key and turn the ignition switch to the “On” position (Do not start the engine). Leave the switch on for 11 minutes. The security light may flash or be on steady during this 11 minute period. Make sure the light is no longer on or flashing before proceeding to #2 .
2. Turn the ignition switch off for 30 seconds.
3. Turn the ignition switch to the “On” position (as in step #1) for 11 minutes again.
4. Turn the ignition switch off for another 30 seconds.
5. Turn the ignition switch to the “On” position for 11 minutes a third time.
6. Turn the ignition switch off for 30 seconds one final time.
7. Turn the ignition switch to the “On” position one final time and wait 30 seconds.
8. Attempt to start the engine. If the engine starts and runs normally, the relearn is complete. If the engine does not start, check for trouble codes and address them before attempting the relearn procedure again.
is this the correct process for the trailblazer ??
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  #2  
Old 06-19-2011, 10:44 AM
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Trailvoys don't have resistors in the keys - the Passkey system. We have resistors in the key cylinder - the Passlock system. Not certain if it needs a relearn, but a BCM almost always (thanks to GM's evil designers) needs a dealer process to install all the OPTIONS properly. The shop manual assumes you're a dealer with access to a Tech II tool. Sorry.
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  #3  
Old 06-19-2011, 11:34 AM
07TB 07TB is offline
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I think you will need access to a Tech2 to program the BCM.
Some important info for replacing the BCM:

The ignition switch should be in the OFF position when connecting or disconnecting the connectors to the body control module (BCM).

• Always disconnect the 40-way body wiring extension FIRST, the 32-way tan connector SECOND and the 24-way gray electrical connector LAST.

• Always connect the 24-way gray electrical connector FIRST, the 32-way tan connector SECOND and the 40-way body wiring extension LAST.

• The BCM can set DTCs with the ignition switch in the OFF position. The BCM has battery run down protection for the courtesy lamp circuit. The BCM battery run down protection cannot detect shorts on inputs or other circuits which the BCM does not control. Use the scan tool in order to activate the POWER DOWN NOW mode. Use the POWER DOWN NOW mode in order to check for current draws on circuits that are not controlled by the BCM, or controlled by the battery run down protection system.

• Do not touch the exposed electrical contacts of the body wiring extension. Do not open the BCM housing. The module does not have any serviceable components. The module may be replaced only as an assembly.


Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

For Vehicles equipped with OnStar® (UE1) with Back Up Battery:


The Back Up Battery is a redundant power supply to allow limited OnStar® functionality in the event of a main vehicle battery power disruption to the VCIM (OnStar®module). Do not disconnect the main vehicle battery or remove the OnStar® fuse with the ignition key in any position other than OFF. Retained accessory power (RAP) should be allowed to time out or be disabled (simply opening the driver door should disable RAP) before disconnecting power. Disconnecting power to the OnStar® module in any way while the ignition is On or with RAP activated may cause activation of the OnStar® Back-Up Battery (BUB) system and will discharge and permanently damage the back-up battery. Once the Back-Up Battery is activated it will stay on until it has completely discharged. The BUB is not rechargeable and once activated the BUB must be replaced.

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Body Control Module Programming and Setup
Body Control Module (BCM) Replacement
If the body control module (BCM) is replaced, the following procedures must be performed in the following order:

•BCM Reprogramming--Refer to Body Control Module (BCM) Programming/RPO Configuration in Computer/Integrating Systems.
Important: This procedure has to be performed only for vehicles equipped with Passlock™ System.

•Theft Learn--Refer to Programming Theft Deterrent System Components in Theft Deterrent. A new BCM will learn the Passlock™ information automatically but the powertrain control module (PCM) must still learn the theft information from the BCM.
•Relearn Restraints ID--Refer to Body Control Module (BCM) Programming/RPO Configuration in Computer/Integrating Systems.
BCM Reprogramming
If the BCM is reprogrammed, the following procedures must be performed:

•BCM Reprogramming--Refer to Body Control Module (BCM) Programming/RPO Configuration in Computer/Integrating Systems.
Important: This procedure has to be performed only for vehicles equipped with Passlock™ System.

•Theft Learn--Refer to Programming Theft Deterrent System Components in Theft Deterrent.
•Relearn Restraints ID--Refer to Body Control Module (BCM) Programming/RPO Configuration in Computer/Integrating Systems

Body Control Module BCM Programming/RPO Configuration
Introduction
All the procedures below are designed to set-up a new body control module (BCM) correctly during BCM related service. Some of the procedures may need to be performed separately when replacing other modules or components. Before you start, read these procedures carefully and completely.

Important: The following procedures must be followed:

•Programming the BCM
•Programming Theft Deterrent System Components, if equipped with Passlock System
•Relearn Restraints ID
Programming the BCM
Important: After the procedure is completed, the personalization settings of the BCM are set to a default setting. Inform the customer that the personalization must be set again.

Perform the special function for BCM "Request BCM Info. for SPS" or select Service Programming Systems, and then refer to Service Programming System (SPS) in Programming and Setup.

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Programming Theft Deterrent System Components
Important: This procedure has to be performed only for vehicles equipped with Passlock System.

If the 10 minute learn procedure is chosen, perform the special function for BCM "Request VTD Info. for SPS" or select Service Programming Systems, and then refer to Programming Theft Deterrent System Components in Theft Deterrent. If the Programming Theft Deterrent System Components in the Theft Deterrent procedure is not performed after a BCM replacement, one of the following conditions will occur:

• The vehicle will not be protected against theft by the Passlock System.

• The engine will not crank or start.

This procedure also needs to be performed when replacing the passlock sensor or when replacing the PCM with one used before in a different vehicle.

Relearn Restraints ID
Perform the special function for BCM "Setup SDM Serial Number in BCM" with the scan tool.

This procedure may also need to be performed when replacing the SDM.

Important: After programming, perform the following to avoid future misdiagnosis:

•Turn the ignition OFF for 10 seconds.
•Connect the scan tool to the data link connector.
•Turn the ignition ON with the engine OFF.
•Use the scan tool in order to retrieve history DTCs from all modules.
•Clear all history DTCs.

-------------------------------------------------------------------------
Programming Theft Deterrent System Components
Important:

• If replacing the BCM with a GM Service Parts Operations (SPO) replacement part, the module will learn Passlock™ sensor data code immediately. The existing PCM however, must learn the new fuel continue password when the BCM is replaced.

• If replacing a PCM with a GM SPO replacement part, after programming, these modules will learn the incoming fuel continue password immediately upon receipt of a password message. Once a password message is received, and a password is learned, a learn procedure must be performed to change this password again. A PCM which has been previously installed in another vehicle will have learned the other vehicle's fuel continue password, and will require a learn procedure after programming to learn the current vehicle's password.


Conditions
Use this procedure after replacing:

• Passlock™ Sensor

• BCM

• PCM

Learn Procedures
There are 2 available methods to perform the programming procedure:

• A 10-minute procedure which requires a Tech 2 and a techline terminal.

• A 30-minute procedure which does not require the use of any tools.

10-Minute Learn Procedure
Tools Required
• Tech 2

• CANdi Module

• Techline terminal with current Service Programming System (SPS) software

•Connect the Tech 2 to the vehicle.
•Select "Request Information" under "Service Programming".
•Disconnect the Tech 2 from the vehicle and connect it to a Techline terminal.
•On the techline terminal, select "V.T.D. - Vehicle Theft Deterrent Learn" under Service Programming".
•Disconnect the Tech 2 from the Techline terminal and connect it to the vehicle.
•Turn ON the ignition, with the engine OFF.
•Select "Program ECU" under "Service Programming".
•At this time you will receive a screen on the Tech 2 stating to "PLEASE WAIT-MINUTES REMAINING 10".
•Turn OFF the ignition, and wait 30 seconds.
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  #4  
Old 06-19-2011, 01:21 PM
hpimichael02's Avatar
hpimichael02 hpimichael02 is offline
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2005 Chevy TrailBlazer LS
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great info thanks, would be soo helpful... wish i had 1400 for a tech 2 toold lol
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  #5  
Old 06-19-2011, 09:24 PM
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BUC NASTY BUC NASTY is offline
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The BCM color that you mention is the newer version just like mine so you fine.

But if your thinking of getting the updated version of the bcm you might have to update your PCM to the lastest version as well or else face the consequence of electric problems...
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