I have a 2002 C5 Convertible. Just bought it last month. All was good until I drove in the rain (With the top up). I noticed the A/C didnt work at that time and the car was fogging up but kept the A/C on anyway. Then the next day it wouldn't crank, passenger door locks and window stopped working, and the DIC says reduced power and check tire pressure and shocks inoperable. I had my garage plug on a handheld and it says no comm to BCM. I also did the DIC check that I learned at this site and it also says no comm to BCM along with alot of other codes. I took a video of the DIC spitting codes but it is 1MB larger than I can attach here! Darn! I checked for water by the BCM and didn't even find any dampness at all, NOTHING! Even under the beautiful carpets, it is not even damp! The car and carpets seem brand new and dry! I checked the udders also! Clean and nice! I haven't looked at the EVAP drain yet however but all seems dry! I went to Rock Auto to purchase a new BCM and found 3 there and my part number (10304931) is, of course, the $600 one! Should I buy one anyways? Does anyone have one for sale cheaper? Should I look somewhere else? Does anyone have any advice at all? Thank You so much for letting me join!

 

There are a lot of things that can cause no comm with the bcm. I would investigate a little more before replacing a 600 dollar bcm. Do a search on bcm no comm, lots of suggestions.

 

You should follow the advice of 8VETTE7 and post all the codes.

 

OK I posted the video on YOUTUBE. Here is the link. I did however already purchased a good used BCM on eBay since it was only $99. The guy had sold 47 of them and had 8 left. He also had 99.9% good feedback. I have a good friend that owns a garage and knows a guy that can program it to the car. I also checked the BCM fuses. My buddy at the garage noticed some corrosion on the board so I figure that just might be the issue! It should be here by Monday

 

I did try that actually.No Luck, however. Thank You for the reply! Do you know anything about the codes in the video?

 

I would start by addressing the loss of communication with BCM. These comunications take place through the Serial Data Bus, and it seems something is not allowing the normal data flow. Once the Serial Data Bus is corrupted all other devices that use it get affected.

This problem has been extensively documented by Bill Curlee and you can read more here. It is usually caused by bad contacts in a connector within the doors' rubber accordion.

The Serial Data Bus goes through the rubber accordion to the door control module. The female pins of the connector on that wire harness get deformed, causing bad contacts and loss of communication/corruption in the Serial Data Bus affecting all modules linked by it.



You can troubleshoot by opening the Star Connector 2 by the passenger's foot well, which isolates both Door Control Modules along with the Left Seat Control Module, and if communications are restored then you have your culprit.

Check the connectors for deformed pins. If bad pins are found you would need to repair the connector, fixing the female pins so they have a positive grip, or replace it. If you want to replace the connector take a look at this post for some ideas.

If connectors are fine, then the problem should be downstream the connectors up to the door control modules, or in the wiring/connector for the driver's seat up to the seat control module.

 

Just had a similar problem less than a month ago with no comm and all the same warning lights coming up. This above was the fix, now everything is back to normal...I would try that first before replacing the BCM imo.

 

I will check the pins in the passenger footwell this afternoon and solder the wires if necessary if they look deformed. The passenger window and passenger door lock was the first thing to stop working one day before it poured like cats and dogs with ALOT of humidity and alot of fogging up on the inside of the car. The next day everything went wacko and it wouldn't start as I mentioned previously. I even noticed how the rotors on the car were all rusty looking as I walked up to it the next morning. I did receive the used BCM computer from eBay yesterday and the guy should be coming to the car to program it tomorrow (Saturday). We will see how it goes! Thanks! I will post an update Saturday evening!

 

As I mentioned in my previous post, the Star Connector 2 by the passenger's foot well is just a troubleshooting tool and shouldn't require any soldering. The potentially deformed female pins are in the connector inside the doors' rubber accordion (see picture above).

The Star Connector 2 is the one that has four wires. To perform this test you have to pop the top shorting strip off the top of that connector.



That might be a clue giving this possibility a higher probability.

I would troubleshoot first, as explained in my previous post, before messing around with the BCM.

Let us know how it goes

 

OK so, I cleaned up the grounds on top of the frame rails in the engine compartment, checked the pins in the connectors, and they all looked really good. I fished out the 2 connectors in the passenger door rubber connectors and they definitely look a little spread so I tried to tighten them but it didn't seem to make any difference. I have a guy coming to the garage tomorrow to program the new (Used) BCM to the car but instead performed the emergency procedure I found on this forum to learn the PCM myself and the car now starts!!! Honestly, I can't find anything that doesn't work except for the odometer doesn't show the mileage on the car and the passenger window and door lock still doesn't work. The radio didn't work with the old BCM's problem but now it does. I guess the VATS won't work either from what I've learned. What else wouldn't normally work before the Tech 2 programming? I am very happy that it's running and so much seems good, however! Is the reason that the passenger lock and window doesn't work have to do with the programming? Or do I still have an issue with that somewhere else? Because the drivers' window and lock work fine at this point. I've attached a pic of the plug that has not so good looking female connections between the passenger door. I can easily cut that connector out of the loop and solder them but figured I would ask first if it has something to do with programming the BCM or not.

 

YES, I performed this procedure below but haven't driven it yet. I read in another post a fellow was having issues with his car shutting off after going 2mph after doing the same procedure. I do have the programmer coming tomorrow to program the VIN and I guess to make sure everything else works. I will verify that I can drive it as well as other options. Thanks for the info on locks. I will start with shaking connectors, then check relays. I also ordered a VXDIAG VCX Nano GDS2 and Tech2Win Diagnostic Programming System for GM on Amazon to play with. I'll probably order another BCM because the price was right for sure. I am thinking possibly for the next time that this happens! Being a network support engineer, I am very interested in checking out all the options such as having the A/C blower run for an extra 4min to dry off the evaporator elements to prevent mold as I read in another post.

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

 

Did all the "No Comm" codes go away? Is there any code regarding the RDCM?

When you say that the passenger window and door lock still don't work have you verified if that is the case in all these 3 scenarios?:

1. Window and lock actioned from the driver's side
2. Lock actioned from the key fob
3. Window and lock locally actioned from the passenger's side

The first 2 actions involve communication through the Serial Data Bus, while the 3rd action does not.

If they don't work in neither of the 3 mentioned scenarios, you might have problems with the relays as suggested above, but if the problem is only with 1 and 2 while 3 is fine, then it should be either a comm problem with the RDCM or that the RDCM is not processing the commands from the BCM.

The female pins of your passenger's connector don't look good and that might be a problem. They need to have a positive grip. Bill Curlee uses a male pin attached to a short wire to test the grip by inserting and removing it in each female pin.

Compare your connector to Bill's picture. They look very similar (actually, yours looks worse ):

Yours

Bill's

If you can't fix those female pins, you would have to replace the connector or, as you mentioned, make direct connections soldering and using heat-shrinking insulation. I posted a link before to give you some ideas if you're going the replace route.

 

OK! So, YES, I cleared all codes after new (USED) BCM programming today and after reading your post checked the female pins and was able to dramatically tighten them fairly easily with a flat head jewelers screwdriver. There's a tiny bit of play in the plastic holder for each female pin so I was able to move it a bit and get the tip of the screwdriver in just the right spot and close the gap just perfectly. I then, checked fuse number 31 as after I reset the codes and tried to reset RDCM, I could not, as 2 codes immediately came back right before my eyes. One was B2265 Horizontal Position Sensor Fault, obviously because my inner mirror components are all messed up with the mirror actually trying to fall out. I have a whole new complete mirror assembly at the body shop right now being painted so I am aware of that issue. The other code was B2285 which got me to search that in this forum and I landed on a thread which said to check fuse number 31 and that was that! So Thanks for all your help with all that! What a relief! Which brings me to a bit of a concern I now have. Before the old BCM blew, I never even heard the steering wheel lock motor (at least I don't recall hearing it). I did call the dealer when I got the car and asked if the recall was performed and they said that it definitely was, but couldn't tell me what type of disabler was used. I hear the motor, but it doesn't lock. I read 8VETTE7's post on the LMC5 disabler device and think maybe I should order one right now possibly? Should I worry about it? I am honestly. THANKS AGAIN FOR EVERYTHING!

 

YES, The passenger door lock and window now works! It was fuse number 31. I have a manual transmission. I will order the LMC5 right now. Will it stop the lock motor noise? I forget, but will study up on that installation tonightThat noise is a bit annoying but no big deal. It makes me think that it is going to lock!

 

OK! Great!
Super explanation and I completely understand. I just ordered it and will have it Thursday. I will do exactly as you instructed. I buttoned up the car tonight and will take it for a short ride tomorrow to see if it goes over 2mph after the BCM programming. I have NO CODES except the right mirror code that I mentioned earlier! I cleaned all four udders and pulled off the AC hose on firewall until I see something come out of it tomorrow. I ran the car for 30 minutes-ish tonight and saw no condensation or dripping coming out of the little plastic pipe coming out of the firewall. Also, no water inside next to or above BCM or on the floor. I just had the AC charged today and the dash vents air temp is 39 degrees. It's about 42 degrees here in Connecticut but I still think that there should be some condensation coming out somewhere. Oh well, maybe tomorrow.

THANKS AGAIN!

 

I'm glad your right door is back in business

You are in good hands regarding the LMC5. 8VETTE7 is the Guru in this subject

 

I will be installing the LMC5 later on today. Thanks for the info. I took the car for a rippin' ride today and it is just perfect! I am so impressed with everything about it. I'm hooked! I do have one question. Can I program a spare BCM that I purchased from the same guy on eBay for $99 to the car as well and use the one that is in it right now as a spare so if this ever happens again I can just swap it? Can I have the 2 BCM's programmed for the same car?

 

I am also wondering if you guys would know where this small oil leak might be coming from. It is not dripping on the ground because it's getting burned. I smell oil only sometimes after heavy driving around town. Could it be only the Oil Filter? Doubt it. It is tight!

 

Do you have to do the brown wire for lmc5 on a 99 auto?

 

I had to