My 2000 C5 went for a little fresh water swim and the pass floorboard got wet. I believe the BCM on that side and the fuse block probably got wet too. All the fuses look good, and when I checked power to many fuses in the area they all checked fine at 12+ volts. My problem is the windows, hatch release, and interior lights are INOP. I got the car in this condition with a hydro-locked engine for very cheap. All the other systems seem to work fine. I am currently installing a rebuilt and slightly enhanced LS1 through the top since I am liftless with pretty good success. So my question is; does the BCM control all three of these electrical components? I am afraid it is not water proof and is probably now deceased but would like some knowledgeable input. Also if I have to replace it, does it have to be programmed for the cars VIN or is it a plug and play deal with the proper part number? I also have not been able to try to crank the engine which may be controlled by the same (BCM) due to a rod stuck in the starter housing. Thanks for the help.

 

Yes. It does. It will also have to be re-programmed to your VIN/Security code, etc if replaced.
If it were completely "dead" you would lose other things as well, so maybe it's not. It may be partially damaged though. A Tech II scan tool and some diagnosing will prove very helpful, and I'm not talking just some "code reader" either, but a real scan tool. So will a shop manual with circuit schematics, etc.

Unplug and visibly check the connectors, etc. Look for corrosion, etc. Also, there are relays to consider in addition to the fuses. Worse comes to worse, you can replace it and have the new one programmed to your VIN.

HTH

 

I'm going to get in there and check it out as soon as I can. The dash lights, radio, and gauges seem to work properly so maybe it isn't totally dead like I thought it might be. It does play a part in starting the car doesn't it? I hope the car will at least start and run after I get the new engine in it. I can work out the other problems after that. I'm going to rework all the grounds I read about on another thread to help eliminate any of those problems. How likely could water get into the rear axle/transmission if it was under water for a short time? I'm going to drain and refill them after the engine is done just in case. It is a 6 speed so maybe it will still work if water breached.

 

Yes, it does play a part in the car being started, but you say the radio works and gauges work, which I take it to mean you put the key in and turned to the "on" position, right? They won't turn on otherwise. Only the "dash lights" (parking/headlights) don't need the key turned.

I would advise draining and refilling diff/tranny now. You need to ASSUME, water is in there. Why wait? If water IS in there, it will (potential damage) will only get worse with each passing day.

 

I had replace my BCM because of a blocked drain tube that is on the pass-side lead to a cabin leak on the same side. I had multiple problems with the on board electronics. Took it to a so called "reliable" Vette shop in my area and I indicated on the work order to check the BCM. I got some "bull" about they were making a trace on each problem separate from the BCM. Thanks to this forum I know when a shop is trying to "dance" and has no idea what the problem may be. I just took my car out of that shop, paid 150 for their bull, bit the bullet and brought the BCM part-(200.00) from GMpartshouse. A local GM dealership that sells new/used and races Vettes installed the part and programmed it for 50.00 A last effort you may attempt before the bcm replacement. Disconnect the wire harness from the BCM and reconnect and see what will happen. There are no tests to see if the BCM is damage. So....Good luck

 

Thanks I'll try that on the BCM and yes I have turned the key on to check everything when I first bought it. The HUD works and the computer runs through several messages and checks and the fuel gauge seems accurate. Figured I'd take it out and the fuse block and clean them before re-installing. On the rear axle thing. The car has been sitting for 6 months, but a friend of the previous owner said the fluids were replaced right after it got wet, so I'm hoping the rear has no water in it. If so, it's been in there long enough to do some serious damage. The shifter rows the gears fine so hopefully...The previous owner got caught on a flood prone street and blew the engine and said water got just above the door sills so hopefully there are no other computers down low. Thanks again for the insight.

 

Another item to add to your check-list might also be for any corrosion in/on the connectors under the driver/passenger seats.

A good, competent repair shop that has a Tech II scan tool, can check the BCM test protocols and see if there are any communication ("comm") errors showing. Not sure if you know, but a Tech II can turn on/off/adjust/check darn near anything electrical in the entire car. Heck, if the darn things didn't sell for $2000-$3000, I would have bought one myself long ago.

 

Use the DIC to read the codes. They may give you a place to start diagnosing the problem. Post them here and some of us may be able to help. Check the ground at G202 which is at the base of the passenger A pillar.

Bill

 

Good idea Bill. Btw, there's another one in the identical place on the driver's side too. G201 IIRC.

 

Yes. It is G201. I chose G202 because all of the interior lights except the rear compartment lamp are grounded at that point. One of the BCM grounds is located at that point as well.

Bill

 

I gotcha. Makes sense.

I guess I'm just thinking about water intrusion into the pass. compartment floorboards on both sides of the car.

I definitely don't envy the amount of work involved on a water or partial water car.

 

Yep,,the BCM is complex and very sensitive! It hates water/moisture and CORROSION! My 98 Coupe had a clogged HVAC drain for quite a while. Back then, it was a very unknown issue. The BCm would get wet damp most of the time that the AC was used. After running the AC on humid days, the IPC would freak out. After a few months of that issue, it went DEAD!

I cant just throw things out so,,,I removed the circuit board from the silver box and low and behold there was tons of corrosion on the lower portion of the board. A few minutes with a soft brissle brush and WHAM,,,,,It was good as new!

SO,,,DISCONNECT the battery, disconnect the BCM, pry open the box, remove the board and inspect it. If it is corroded, scrub it off, clean it, repair the traces if there damaged and retest it.

Before you get too deep into the BCM, read and post the DTCs as Bill Dearborn suggested. Those DTCs actually tell us a LOT about the issues that have or are happening. If there are a TON of DTCs, clear all of them and then post the ones that come back. If your NOT familuar with reading your own DTCs using the DIC display,,, here ya go:

READING YOUR Engine Diagnostic Codes (DTCs)

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 etc…)
3) Press and hold OPTIONS
4) While holding OPTIONS, press FUEL four times within a 10-second period.

Initially, on-board diagnostics go into an Automatic Mode which 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. ( 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 kinds 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.
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.

Here is very good site of DTC definitions:


http://www.gearchatter.com


Make sure to include the H or C suffix!!


BC

 

I'm sitting in on this one, all the brains are here!!!!!!

Waiting on the DTCs...