Question about 2002 GMC Envoy

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In programing a body control modual, how do I know when the bcm is in communication with the pcm. thanks

I haven't tried anything yet as I want to get all the infor before I order the BCM. My main concern is the rear wiper motor operated from this bcm as my rear wiper does not work. replaced a new switch and will check for fuse blown and current to the switch

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  • Joe Colella
    Joe Colella Dec 16, 2014

    I received a response earlier from a Ali Galam in which part of the explanation on installing a BCM, that in doing so I have to make sure that the BCM communiates with the PCM , the passkeumodual and my question was how would I know if the two are communicating

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  • 17 Answers

Check first the wiper motor if althe power is ok then change the bcm

Posted on Dec 17, 2014

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1 Answer

Where are all the ground wires located on a 2008 chevy cobalt?


It wouldn't be a ground problem If it were the whole instrument cluster would be dead . Checking the BCM an the IPC for DTC'S - diagnostic trouble codes is the proper way to diagnose this type problem . Not worrying about grounds .
Odometer
The vehicle odometer is calculated and stored electronically in the body control module (BCM) and is sent via the serial data circuit to the instrument panel cluster (IPC) for display. The BCM calculates and stores the mileage based on the vehicle speed serial data information from the PCM/ECM. The IPC displays the season odometer information from the BCM in the driver information center (DIC). The odometer will display error if the IPC detects an invalid odometer data from the BCM. After an invalid odometer data is received from the BCM, the IPC will display the last known odometer reading for 1.5 seconds before error is displayed in the DIC.
Speedometer
The instrument panel cluster (IPC) displays the vehicle speed based on serial data message from the body control module (BCM). The BCM receives vehicle speed data from the PCM/ECM via the serial data circuit. The speedometer will default to 0 km/h (0 mph) if:
• The PCM/ECM detects a malfunction in the vehicle speed sensor circuit.
• The BCM detects a loss of serial data communications with the PCM/ECM.
• The IPC detects a loss of serial data communications with the BCM.

Your best bet would be to take it to the dealer !

Apr 19, 2017 | 2008 Chevrolet Cobalt

1 Answer

2002 chevy malibu cranks wont start. fuel and temp gauge dont work. radio reads cal


Cranks won't start , Did you check for spark ,fuel pressure ?
Radio Setup .Will the vehicle communicate with a scan tool ? Fuel an temp gauges not working are probably bad step motors inside the instrument cluster that controls the gauges . Where do the gauges read 0 or something else ?
Engine Coolant Temperature Gage
The IPC displays the engine coolant temperature as determined by the PCM. The body control module (BCM) receives a class 2 message from the PCM indicating the engine coolant temperature. The BCM converts the engine coolant temperature into a percent gage deflection. The IPC receives a message from the BCM via the serial peripheral interface (SPI) indicating the requested gage position. The engine coolant temperature gage defaults to 38°C (100°F) or below if:
?€¢
The PCM detects a malfunction in the engine coolant temperature sensor circuit.


?€¢
The BCM detects a loss of class 2 communications with the PCM.


?€¢
The IPC detects a loss of SPI communications with the BCM.

Fuel Gage
The IPC displays the fuel level as determined by the PCM. The body control module (BCM) receives a class 2 message from the PCM indicating the fuel level percent. The BCM converts the fuel level percent into a percent gage deflection. The IPC receives a message from the BCM via the serial peripheral interface (SPI) indicating the requested gage position. The fuel gage defaults to E (empty) if:
?€¢
The PCM detects a malfunction in the fuel level sensor circuit.


?€¢
The BCM detects a loss of class 2 communications with the PCM.


?€¢
The IPC detects a loss of SPI communications with the BCM.

When the fuel level is less than a pre-determined value, the low fuel indicator illuminates.
DTC P0462
The fuel level sensor changes resistance based on fuel level. The PCM monitors the signal circuit of the fuel level sensor in order to determine fuel level. When the fuel tank is full, the sensor resistance is high and the PCM senses a high signal voltage. When the fuel tank is empty, the sensor resistance is low and the PCM senses a low signal voltage. The PCM uses the signal circuit of the fuel level sensor in order to calculate the total remaining fuel in the tank. The PCM sends the fuel level percent via the class 2 serial data circuit to the body control module (BCM). The BCM converts this data and sends a fuel gage percent deflection to the IPC via the serial peripheral interface (SPI) in order to control the fuel gage. The fuel level information is also used for misfire and EVAP diagnostics.

Have
For the DE 100 series radio, complete the following procedure, using a scan tool, in order to properly set up communication:

  1. At the Main Menu screen, select: Diagnostics.
  2. At the Vehicle Identification screen, select the following options:
  3. ?€¢
    Model Year


    ?€¢
    Passenger Car

  4. At the System Selection Menu screen, select: Body.
  5. At the Vehicle Identification screen, select the Platform type.
  6. At the Body screen, select: Radio.
  7. At the Radio screen, select: Special Functions.
  8. At the Special Functions screen, select: Radio Setup.
  9. At the Radio Setup screen, press ENTER. The following test will set up a new or existing radio.
  10. Select one of the following options:
  11. ?€¢
    USA/Canada


    ?€¢
    Export

  12. Press the ENTER key.
  13. Verify that the scan tool displays "Test in Progress."
  14. Verify that the scan tool displays "Test Completed Successfully."
  15. Press EXIT on the scan tool.
Important: The radio set up will configure the following systems:
?€¢
LEARN VIN


?€¢
Diagnostic Trouble Codes


?€¢
Class 2 Radio Messages


?€¢
Country Code


?€¢
Chime Volume


?€¢
Chime Level


?€¢
12/24 Hour Clock

Without learning the VIN, the radio will display a locked message (LOC).
The radio setup procedure will also clear the following messages:
?€¢
CAL


?€¢
CAL ERR


?€¢
CALIBRATE

May 29, 2016 | Cars & Trucks

1 Answer

While driving antitheft light comes on and all the gauges go flat,car keeps runnig,want to disable system,not sure what to look for


Before doing something drastic ,have it checked out for DTC'S - diagnostic trouble codes . It may not be the anti-theft system ,gauges going flat would be more like a communication problem between modules . PCM / BCM / instrument cluster etc.. That also could cause theft light coming on . If your not sure what to look for ,take it to a ASE certified professional . You may render your vehicle useless if you don't know what your doing .
Serial Data Power Mode Master
On vehicles that have several control modules connected by serial data circuits, one module is the power mode master (PMM). On this vehicle, the PMM is the body control module (BCM). The PMM receives 3 discrete ignition switch signals to differentiate which power mode will be sent over the Serial Data circuits. The 3-wire Ignition Switch table below illustrates the state of these inputs in correspondence to the ignition switch position:
Serial Data Messages The modules that depend exclusively on serial data messages for power modes. stay in the state dictated by the last valid PMM message until they can check for the engine run flag status on the serial data circuits. If the PMM fails, the modules monitor the serial data circuit for the engine run flag serial data. If the engine run flag serial data is True, indicating that the engine is running, the modules fail-safe to RUN. In this state, the modules and their subsystems can support all operator requirements. If the engine run flag serial data is False, indicating that the engine is not running, the modules fail-safe to OFF-AWAKE. In this state, the modules are constantly checking for a change status message on the serial data circuits and can respond to both local inputs and serial data inputs from other modules on the vehicle.
Indicators and Warning Messages
Refer to Indicator/Warning Message Description and Operation .
Engine Coolant Temperature Gage
The instrument panel cluster (IPC) displays the engine coolant temperature as determined by the powertrain control module (PCM) or the engine control module (ECM). The IPC receives a serial data message from the PCM/ECM indicating the engine coolant temperature. The engine coolant temperature gage defaults to 38?°C (100?°F) if:
?€¢
The PCM/ECM detects a malfunction in the engine coolant temperature sensor circuit.


?€¢
The IPC detects a loss of serial data communications from the BCM.

Fuel Gage
The instrument panel cluster (IPC) displays the fuel level as determined by the powertrain control module (PCM) or the engine control module (ECM). The IPC receives a serial data message from the body control module (BCM) indicating the fuel level. The fuel gage defaults to E (empty) if:
?€¢
The PCM/ECM detects a malfunction in the fuel level sensor circuit.


?€¢
The IPC detects a loss of serial data communications from the BCM.

When the fuel level is less than 14 percent, the low fuel indicator illuminates.
Odometer
The instrument panel cluster (IPC) contains a season odometer and a trip odometer. Momentarily press the trip/reset switch in order to toggle between the season odometer and the trip odometer. Press the trip/reset switch for greater than 2 seconds, while the trip odometer is displayed, in order to reset the trip odometer. The odometer is calculated and stored electronically in the body control module (BCM). The BCM uses the vehicle speed information from the powertrain control module (PCM) to calculate the odometer. The odometer displays 'error' if an internal IPC memory failure is detected. The IPC stores a backup copy of the odometer value incase the IPC stops receiving a valid odometer value from the BCM.
Speedometer
The instrument panel cluster (IPC) displays the vehicle speed based on the information from the ECM/PCM. The IPC receives the vehicle speed information from the BCM via the serial data circuit. The speedometer defaults to 0 kmh (0 mph) when the following occurs:
?€¢
The powertrain control module (PCM) or the engine control module (ECM) detects a malfunction in the vehicle speed sensor circuit.


?€¢
The IPC detects a loss of serial data communication from the BCM.

Tachometer
The instrument panel cluster (IPC) displays the engine speed as determined by the powertrain control module (PCM) or the engine control module (ECM). The IPC receives a serial data message from the body control module (BCM) indicating the engine speed. The tachometer will default to 0 RPM if:
?€¢
The PCM/ECM detects a malfunction in the engine speed sensor circuit.


?€¢
The IPC detects a loss of serial data communication from the BCM.

Apr 07, 2016 | 2006 Pontiac G6

1 Answer

Where is the Body Control Module located?


I'm just curious if your aware of the BCM function's on your vehicle an if you know what the gate way module is ? An do you know about serial data communication between modules ? An do you know what the power mode master is ? And do you know the BCM needs programming ?
The body control module (BCM) in this vehicle functions as a gateway or translator. The purpose of the gateway is to translate serial data messages between the GMLAN high speed buss and the GMLAN low speed buss for communication between the various modules. The gateway will interact with each network according to that network's transmission protocol.
One example of this necessary communication is the communication between the engine control module (ECM)/powertrain control module (PCM) which is high speed serial data and Theft Deterrent Module which is low speed serial data. If these modules can not exchange information, the vehicle will not start.
Communication between the BCM and a scan tool can be on the high speed GMLAN network or low speed GMLAN network. If one network is lost, the BCM can still communicate with the scan tool. A lost communication DTC typically is set in modules other than the module with a communication failure.

Mar 04, 2016 | 2007 GMC Yukon XL Denali

1 Answer

Where is the tempature guage sensor


The temperature gauge sensor as you call is for more then just the temperature gauge . The temp. sensor is an input to the PCM -engine computer ! If it were bad you would have drivability problems , the transmission would not shift correctly an the check engine light would more then likely be lit .
Engine Coolant Temperature Gage
The IPC displays the engine coolant temperature as determined by the PCM. The body control module (BCM) receives a class 2 message from the PCM indicating the engine coolant temperature. The BCM converts the engine coolant temperature into a percent gage deflection. The IPC receives a message from the BCM via the serial peripheral interface (SPI) indicating the requested gage position. The engine coolant temperature gage defaults to 38?°C (100?°F) or below if:
?€¢
The PCM detects a malfunction in the engine coolant temperature sensor circuit.


?€¢
The BCM detects a loss of class 2 communications with the PCM.


?€¢
The IPC detects a loss of SPI communications with the BCM.


Your gauge is more suspect then the sensor . gm had a problem with stepper motors that control the pointer for the gauge !

Sep 01, 2015 | 2001 Chevrolet Chevrolet Malibu LS

1 Answer

Replaced stearing column on a 2000 Silverado now it won't start


Did you change the lock cylinder ? You need to put the passlock?"¢ sensor out of your old steering column into the replacement one. Is the security light lit in the instrument cluster ?
The design of the passlock?"¢ system is to prevent the vehicle operation if the proper ignition key is not used in order to start the vehicle. The mechanical key, in normal operation, will turn the ignition lock cylinder. The passlock?"¢ sensor monitoring the position of the lock cylinder will relay the passlock?"¢ data to the body control module (BCM). The BCM will determine the validity of the passlock?"¢ data. The BCM will send a password to the vehicle/powertrain control module (VCM/PCM). When the VCM/PCM receives the correct password the VCM/PCM allows the fuel injectors to operate normally. The passlock?"¢ system requires the VCM/PCM and the BCM to communicate the various functions in order to operate. These functions transmit over the class 2 serial data line CKT 1807. For an explanation of the class 2 serial data operation refer to Data Link Communications Circuit Description in Data Link Communications

May 09, 2015 | Cars & Trucks

2 Answers

How to remove underhood fuse/relay box


Before you replace another good part. Check grounds. The three main ones are the battery to body, battery to engine and engine to body. When multiple parts , especially when they run off different computers, stop working. It is a ground problem. It's not power as they have different power sources. You also have other ground points in the passenger compartment. check behind kick panels on both sides of the car. Year make and model helps.

Apr 26, 2015 | Cars & Trucks

1 Answer

Where is the anti theft system fuse located on 2001 Chevy cavalier


There is no fuse for the anti-theft system ! It receives it's voltage from the BCM . Do you know what a BCM is ? It is a Body control module .
The Passlock?"¢ System is provided in order to prevent vehicle theft if the ignition lock cylinder is forced to rotate or the ignition switch is operated while separated from the ignition lock cylinder case. If starting is attempted without authorization from the Passlock?"¢ System, the powertrain control module (PCM) will disable engine starting. Start disable may be in the form of fuel disable or starter disable, depending on engine application.
The components of the Passlock?"¢ System are as follows:
?€¢
The ignition lock cylinder and key


?€¢
The ignition lock cylinder case, including the Passlock?"¢ sensor


?€¢
The ignition switch


?€¢
The body control module (BCM)


?€¢
The security indicator on the instrument cluster


?€¢
The powertrain control module (PCM)


The body control module (BCM) contains the logic of the Theft Deterrent System. The BCM provides the battery positive voltage to operate the Passlock?"¢ sensor. The BCM also measures the voltage of the security sensor signal circuit. The voltage measured will indicate whether the Passlock?"¢ sensor has been activated and whether the resistance value from the sensor is a valid value or the tamper value. If voltage measured is in the valid range, the BCM compares this voltage, voltage code, to a previously learned voltage code. If the voltage codes match, the BCM sends a class 2 message containing a password to the powertrain control module (PCM). If the voltage codes do not match, or the voltage is in the tamper range, or there is a circuit fault, the BCM will not send the correct password to the PCM, and the vehicle will not start.
The body control system consists of a BCM and it's associated controls. Battery positive voltage is provided to the BCM from CLSTR fuse in the Fuse Block-left I/P. The module ground is wired to ground G201. The BCM is wired to the Class 2 serial data communication bus as well as discreet input and output terminals to control the functions of the vehicles body !
Now then Karen what problem is your vehicle having , no start an SECURITY light flashing or on solid ?
Now then

Apr 10, 2015 | 2001 Chevrolet Cavalier

1 Answer

Replacing BOdy COntrol Modulle


Not for nonprofessionals! BCM communicates with PCM. Codes are set at at manufacturer for car vin and PCM it communicates with/ Any replacement requires programming via dealer or vehicle will not start.

Feb 12, 2015 | Cars & Trucks

1 Answer

Where is the bcm on a 2007 uplander


What are you trying to do? If you are trying to replace a Body Control module be careful. It is linked very closely to your security system and will prevent your car from starting permanently. BCMs are programed and can't be changed. They have to communicate with the PCM to start the car. In most gm cars they are located behind the glove box.

Apr 06, 2014 | 2007 Chevrolet Uplander

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