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No communication to bcm with scan tool - 2000 GMC Safari

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Is my bcm faulty


Will a scan tool communicate with it ? If a scan tool will communicate with it probably not ,just system it controls has the problem . What make's you think or ask if BCM is faulty ?
Do you know how a BCM works ?
Chrysler US MasterTech December 1995 1996 Grand Cherokee Body Electrical... This is just to give you a idea on what your dealing with

Jul 09, 2017 | Cars & Trucks

1 Answer

Lost current communication with fuel injector control module


Lost current communication with fuel injector control module ? Would you like to try and explain that a little better ? Lost communication with Engine computer PCM/ECM ? A scan tool won't talk with the PCM / ECM ? What type scan tool ? Can your scan tool talk with any other control module on the vehicle ? BCM , EBCM , SRS etc... if you know what those are ? Or current , are you talking about electrical current ? I know I only have thirty years experience as automotive Tech . I need terms that I can relate to .

Dec 01, 2016 | Cars & Trucks

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

Inadv and rap 1 clicks when I try to start a 2002 Tahoe


Did you check for BCM codes
DTC B1477
Retained Accessory Power Circuit Low
DTC B1478
Retained Accessory Power Circuit High
DTC B1397
Device Voltage Reference Out #1 CKT Low
DTC B1398
Device Voltage Reference Out #1 CKT High
Charging system check ?

Diagnostic System Check - Retained Accessory Power
Test Description
The numbers below refer to the step numbers on the diagnostic table.

  1. Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.

  2. This step is checking for DTCs in the BCM.

  3. This step is checking for RAP specific DTCs.

Step

Action

Yes

No

1

Install a scan tool.

Does the scan tool power up?
Go to Step 2
Go to Scan Tool Does Not Power Up in Data Link Communications

2

  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to establish communication with the body control module.

Does the scan tool communicate with the BCM?
Go to Step 3
Go to
Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

3

Important: The engine may start during the following step. Turn OFF the engine as soon as you have observed the Crank power mode.

  1. Access the Class 2 Power Mode in the Diagnostic Circuit Check on the scan tool.
  2. Rotate the ignition switch through all positions while observing the Class 2 Power Mode on the Scan Tool. Refer to the Serial Data Power Mode table within the Body Control System Description and Operation in Body Control Systems, for a list of the power mode states that correspond to each ignition switch position.

Does the Class 2 Power Mode parameter reading match the ignition switch position for all the selected positions?
Go to Step 4
Go to Power Mode Mismatch in Body Control System

4

Select the BCM display DTCs function on the scan tool.

Does the scan tool display any DTCs?
Go to Step 5
Go to the Symptoms list in the appropriate service category

5

Does the scan tool display B1477 or B1478?
Go to
Diagnostic Trouble Code (DTC) List
Go to Symptoms - Retained Accessory Power

May 10, 2016 | Cars & Trucks

1 Answer

I have a 03 envoy xl and replaced the old body control module with a used on how do I reset it?


It has to be programmed for sure if it can be used at all . Most GM vehicle do not allow used BCM'S . It will lock up with out proper vin number an anti-theft system information installed . Your best bet is call the dealer or an independent mobile technician in you area that does reprogramming . If I may ask what kind of problems were you having that makes you think the BCM needed to be replaced ? Was a Professional type scan tool used to see if the BCM was able to communicate ? Were power an grounds checked ? Fuse's etc... I see it a lot working at the dealer , not just GM vehicles either . Customer changed out module when it didn't need it.
If installing a replacement BCM, program the BCM. Refer to Body Control Module (BCM) Programming/RPO Configuration .
An you need a subscription on GM web site , GM scan tool or a J-2534 Pass-through Device programming tool .
The procedures below are designed to set-up the body control module (BCM) correctly during BCM related service. Before you start, read these procedures carefully and completely.
Important: The following procedures must be followed:
  1. Programming the BCM
  2. Programming Theft Deterrent System Components, if equipped with Passlock System
  3. Relearn Restraints ID
If you don't understand what this guy talks about , you really need to take it to the dealer.

Control Module Diagnostics with John Anello

May 08, 2016 | Cars & Trucks

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

My dash in my 2006 canyon isn't working, can't find the problem


Did you have the vehicle hooked to a factory scan tool to see if it will talk to the scan tool . Your instrument cluster is electronic an has a microprocessor inside , it is connected on the serial data communication network or bus as it is called . It's hard to find a problem when you don't know how it works >
All the gauges in the instrument cluster receive there info from the ECM - BCM engine an body computers on the data bus .
The instrument panel cluster (IPC) displays the vehicle speed based on the information from the engine control module (ECM). The IPC receives a serial data message from the BCM indicating the vehicle speed.
PRND321 Display
The instrument panel cluster (IPC) displays the selected gear position as determined by the engine control module (ECM). The IPC receives a serial data message from the ECM indicating the gear position. The PRND321 display blanks if:
?€¢
The ECM detects a malfunction in the transmission range switch circuit.


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


?€¢
The BCM detects a loss of serial data communications with the ECM.


This you should take to a ASE qualified repair facility or the dealer ! It is possible to short out the data bus an bring down the system , meaning nothing on the vehicle will work !

Sep 24, 2015 | Cars & Trucks

1 Answer

Why is my ck engine & passlock light on & won't stay crank but will when I jump relay ?


Hi Pattie , What relay are you jumping ? Run/crank or start relay ?
Your check engine light an passlock light are lit because there is a problem an you need to take it an have it checked out ! Unless you have a factory or equivalent scan tool ! There are DTC'S - diagnostic trouble codes stored in the BCM - body control module an in the PCM - powertrain control module . Your dealing with complex electronics an jumping things you have no clue as to how it works can render you vehicle useless !

The body control module (BCM) performs multiple body control functions. The BCM can control devices directly connected to its outputs based on input information. The BCM evaluates this information and controls certain body control systems by commanding outputs on or off. The BCM control inputs can be:
?€¢
Sensors and switches that are directly connected to the BCM


?€¢
Class 2 serial data received from other control modules connected to the class 2 serial data link.

The BCM is also capable of controlling other vehicle systems that are not directly wired to the BCM. The BCM does this by sending specific messages on the class 2 serial data link. The control module capable of performing the required function will respond to the BCM message.
The data link connector (DLC) allows a scan tool to communicate with the class 2 serial data line. The serial data line is the means by which the microprocessor-controlled modules in the vehicle communicate with each other. Once the scan tool is connected to the class 2 serial data line through the DLC, the scan tool can be used to monitor each module for diagnostic purposes and to check for diagnostic trouble codes (DTCs). Class 2 serial data is transmitted on a single wire at an average of 10.4 kbps. This value is an average, class 2 uses a variable pulse width modulation to carry data and depending on the message it may operate faster or slower. The bus will float at a nominal 7 volts during normal operation. Each module can pull this lower during the transmission. The bus is not at battery positive voltage or ground potential during normal operation. When the ignition switch is in RUN, each module communicating on the class 2 serial data line sends a state of health (SOH) message every 2 seconds to ensure that the module is operating properly. When a module stops communicating on the class 2 serial data line, for example if the module loses power or ground, the SOH message it normally sends on the data line every 2 seconds disappears. Other modules on the class 2 serial data line, which expect to receive that SOH message, detect its absence; those modules in turn set an internal DTC associated with the loss of SOH of the non-communicating module. The DTC is unique to the module which is not communicating, for example, when the inflatable restraint sensing and diagnostic module (SDM) SOH message disappears, several modules set DTC U1088. Note that a loss of serial data DTC does not normally represent a failure of the module that set it.
Body Control Module (BCM)
The body control module (BCM) contains the logic of the theft deterrent system. The BCM provides the 5-volt reference to operate the Passlock?"¢ sensor. The BCM also measures the voltage of the off/run/crank voltage. 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 to a previously learned voltage code. If the voltage codes match, the BCM sends a serial data message containing a password to the engine control module (ECM). 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 ECM, and the vehicle will not start.

May 18, 2015 | 2005 GMC Canyon Extended

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

The power door locks, windows, interior lights, and radio all stopped working on my 2002 Rendezvous. One morning my key fob would not unlock the car and so I did it manually and the security light stayed...


What kind of place did the diagnostics ? Auto part stores ? The BCM - body control module . Takes a proessional or factory scan tool to pull codes from this module .
The body control module (BCM) is capable of accomplishing multiple body control functions. Components directly connected to the BCM are controlled by the BCM outputs. The BCM can control its outputs based on input information it obtains from sensors and switches that are directly connected to the BCM, or by receiving information from other vehicle systems connected to the class 2 serial data link. The BCM evaluates this information and controls certain body systems by commanding an output on or off.
The BCM is also capable of commanding other vehicle systems to control functions that are not directly wired to and/or controlled by the BCM. The BCM accomplishes this task by sending specific messages on the class 2 serial data link. The vehicle system capable of performing such function will respond to the BCM message.
The BCM controls/monitors the following functions:
• Audible warnings
• Indicators control
• Interior lighting
• Exterior lighting
• Power/automatic door locks
• Keyless entry
• Content theft deterrent
• Personalization
• Serial Power Modes
• Electrical Power Management

Hooking up a Tech 2 factory scan tool to see if the BCM will communicate would be the first step in diagnosing this problem ,also checking codes an to see if the scan tool can bidirectionally control the lock's window's etc.. I would suggest a buick dealer !

Jun 10, 2017 | 2002 Buick Rendezvous

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