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Old 03-11-2010, 03:18 PM   #1
machz800ps
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Default body control module bad??

Hey guys im going to go look at a 2002 z06 this week end 32k on it original owner, he says body control module is bad, about an $800.00 dollar part he says, is this correct and what would cause it to go bad he said he was told a common problem. also what else should i look for or ask about this car

Thanks in advance
Steve
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Old 03-11-2010, 03:21 PM   #2
dougbfresh
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NOT a common problem. Why does he claim it's bad?
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Old 03-11-2010, 03:30 PM   #3
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he said he had gotten either some codes or an check engine or something dont remember at this point but said he had it look at and they told him the bcm was bad (they i assume being the dealership) i can call him and get a better discription of how he determined it is the bcm. again i have not seen the car yet

thanks
Steve
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Old 03-11-2010, 03:42 PM   #4
dougbfresh
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You can get computer codes directly from the car without a scanner-search for pulling codes. You can do it from the DIC (Driver Information Center). Write them down. The 1 problem that CAN take out a BCM is a clogged AC drain tube. It clogs, water backs up into the passeneger footwell ad drowns the BCM (and leaves the carpet WET).
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Old 03-11-2010, 04:08 PM   #5
machz800ps
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Thank you sir!! anything else i need to check for on this car besides the basic wear items

Steve
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Old 03-11-2010, 04:11 PM   #6
dougbfresh
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Pulling the computer codes is your best insurance. Write them doen and come back with what you find, especially any letters on the end of the (H for Historic and/or C for Current). Historic's are old and can be cleared generally, the Current ones are usually the ones to be concerned with. Many people write them down, clear them all and see which (if any return).

Here;s how to pull them and what they mean:
http://www.stengel.net/diccodes.htm

Last edited by dougbfresh; 03-11-2010 at 04:19 PM.
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Old 03-11-2010, 05:18 PM   #7
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Definitely get the codes if any are available from him. It may not always be the BCM depending on what codes are being thrown. A dealership is always going to start with the control module as the culprit though, could be as simple as a ground wire that needs to be cleaned due to corrosion or some other sensor. If there are any aftermarket components on the car, check back with us to see if they could be causing any issues. C5's do have there share of electrical gremlins, but most are easy to fix or diagnose. Especially with the help of this forum. Good luck with the purchase, you won't be disapointed

It's definitely a good sign if the owner is offering up this information to you before the purchase. Sounds like an honest guy. I assume he's knocking the 800.00 off the price.

Last edited by MG RED 99; 03-11-2010 at 05:20 PM.
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Old 03-11-2010, 11:26 PM   #8
Bill Curlee
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Follow this procedure and read your own DTCs If there are a lot of them, just clear them and take the car for a drive.

READING YOUR Engine Diagnostic Trouble Codes (DTC)

This procedure should be carried out any time you experience a problem with your C5. Most inexpensive store bought aftermarket code readers will ONLY read power train DTC’s. Reading the DTC’s with the C5 built in code reader will allow you to read ALL the modules in the vehicle.

The Diagnostic Display Mode is entered with the following procedure:
1) Turn on the ignition but don't start the engine.
2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open ect)
3) Press and hold the OPTIONS button
4) While holding OPTIONS, press FUEL button four times within a 10 -second period.

Initially, the on-board diagnostics go into an Automatic Mode which will cycle through each module and shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each module. ( i.e. PCM = 4 codes) If none are present in a given module, you will see No More Codes on the display.

There are two types of diagnostic codes, Current and History designated with a letter suffix, “C” or “H”. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes. More likely it's an indication of an intermittent malfunction.

Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.

Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present; press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press RESET To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles. There are a few body module DTC’s that if set will prevent the module from operating properly. Once the DTC is cleared, the module will return to full function. This is not true for power train DTCs.

If you have never read and cleared your codes, there will probably be a lot of old history DTCs. It is recommended that you clear your codes and see if any come back during a driving cycle. Those are the ones that you need to concentrate on diagnosing.

Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5.

NOTE and a WARNING. You can read the DTCs while the engine is running. I pull mine up all the time while driving.
WARNING. Don’t become distracted while reading DTCs while your driving and cause an accident!!!!! Use common sense and drive safe.

These are some very good C5 Diagnostic Trouble Code (DTC) explanation web sites!!! They also explain how to read the DTCs

Here are some very good sites that explain what DTC mean:

http://www.gearchatter.com/viewtopic11755.php

http://www.obd-codes.com/trouble_cod...d-ii-codes.php

Make sure to include the H or C suffix when you post your DTCs!!




---------------------------------------------------------------------
You will KNOW if the BCM is dead. The car wont crank. There are other things that go wrong and the module is NOT $800. When I purchased mine from Gene Culley www.gmpartshouse.com I believe it was around $250.

Its not a plug and play module. You will need to perform a BCM/PCM emergency SYNC procedure and then take the car to the dealer and have any RPO codes that you have for your programmed into the BCM with a TECH II.


BCM/PCM RELEARN PROCEDURE


You will need to conduct the PCM/BCM relearn process. This matches their handshake ID's and allows them to talk to each other.

Do this before you worry about VATS issues:

1. Turn on the key for 11 minutes.
2 Turn off the key for 30 seconds.
3. Repeat 1&2 two more times.
4. Turn on the key for 30 seconds.

The car should start and run with the new BCM. Good luck and report back on your progress.
Shirl
SD Racing Enterprises
Aguila, AZ
Coutersy of MrEracer


This will sync the PCM to the New BCM but all of your RPO options will not be retained. You will need a TECH II to program them into the new BCM.

There is a very common problem with the wiring harnesses inside the rubber accordion tubes that connect the door to the door frame. The serial data wires get corrupt and cause all sorts of weird issues. If you pinch the tube and grip the two small harnesses between your fingersand then shake the hell out of them, that will usually temporaliry resolve the serial data buss problems.

Click the image to open in full size.

Click the image to open in full size.

Bill Curlee

Last edited by Bill Curlee; 03-11-2010 at 11:31 PM.
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Old 03-12-2010, 01:16 AM   #9
kg54trains
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Quote:
Originally Posted by machz800ps View Post
Hey guys im going to go look at a 2002 z06 this week end 32k on it original owner, he says body control module is bad, about an $800.00 dollar part he says, is this correct and what would cause it to go bad he said he was told a common problem. also what else should i look for or ask about this car

Thanks in advance
Steve
BC stated cost is 250.00 from Gene at GMpartsHouse.com and I paid the same from Gene when my unit failed. Water back up and entered on the passender side and flowed over the unit. Car started but various functions failed and they would not work. I installed the unit and took it to a GM dealership that specialized in the sales and service of corvettes. The dealership charged 80.00 to complete the new unit install. It resolved all my problems. My water problem was not from the A/C discharge but the drain/utter from the the passender side was totally blocked by a clog and this lead to a leakage in the car cabin that flowed over the old BCM. I have a 98 C5 coupe so I clean those drains every spring. I even cut the utter's splits a little more so as to reduce a future clog.
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Old 03-12-2010, 01:08 PM   #10
Bill Curlee
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Before you get to wrapped up in getting a new BCM, read the DTCs and see what they tell ya. If you have a TON of NO COMMUNICATION DTCs other issues are most likely cusing the problem.

I have that solution also.

Us ZO6 guys need to stick together!

BC
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Old 03-12-2010, 01:08 PM
 
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