LPDesRoche

Ok let me tell what I believe to be the whole story. About a month ago my A/C condensate drain clogged up to the point I had flooded my floor boards on both sides. Mainly the passenger side in turn soaking the BCM. Car while this was all wet the car had numerous weird electrical issues (blinkers fast blinking, factory alarm going nuts, interior lights and radio not turning off, etc) Once I got home that day I took everything out, all the carpet, the BCM, HVAC blower motor, and unclogged the drain. Dried it all for a few days and reassembled. When I started the car everything was back to normal except my security light on the dash now stayed lit. Car ran and drove fine but the security light was on. I figured the BCM was just having a minor issue and looked for a used one and continued to drive the car evey few days. Well a week or so goes by and after the drain working perfect during that time it clogs up again and floods the passenger side floor board once again as well as the BCM. Same procedure, took it all apart cleaned/dried and unclogged. I put the car together a few days later and start it up to move it into the garage starts and runs fine but NO security light this time. I thought that was strange but figured WTH and just wrote it off to weird electrical gremlins due to the water. Car then sits in the garage for a few days I go to use it and now it doesn't start. All lights come on, good voltage, just nothing when I turn the key. I try to tap the starter a bit and still nothing. I even try to push start it and get nothing there either?? So I was thinking the BCM was toast, new/used one arrives and I hook it up and same exact thing. All the lights but no start?

Where do I begin to diagnose this problem? You have my full attention. This has Bill Curlee written all over it, you have helped me in the past with other elec issues and I thank you for it.

Any suggestions guys/gals?

BigGun

You forgot to post the codes.

dgrant3830

Not even going to attempt to start troubleshooting this as you are correct in that this needs Bill's attention or Lucky. I will however suggest that you need to find out what's clogging up the udders and causing this all to happen again. What kind of junk are you getting out of the udder?

LPDesRoche

Ok, as for the stuff thats clogging the HVAC drain I have no clue. I jacked the car up climbed under and ran a ziptie through the tube and it flowed clean and drained right out. It drained like it was supposed to for a weeks worth of driving. Then it clogged up again and all I did was touch the rubber drain tube with my finger and it started to pour out once again. I had planned on troubleshooting it further then the no start thing happened. Which I need to get resolved first.

Here are the codes that I just pulled. I got 2 different sets. One with the original BCM and another set with the BCM that I purchased used off the forum.

Original BCM Codes:
PCM P1631 HC
BCM B0502 H
B0507 H
B2483 H
B2527 H
B2528 H
B2721 H
B2722 H
B2723 H
RFA U1000 H
U1064 H


Here are the codes with the new/used BCM:
PCM P1631 HC
SDM B1001 HC
BCM B2721 HC
A0-LDCM B2284 H
B2264 H
U1064 H
A1-RDCM B2285 H
U1064 H
B0-RFA U1000 H
U1064 H

I pulled the codes with the used replacment BCM first, then cleared them. Disconnected the battery, swapped BCM's back to the original and repulled the codes.


Leeland

dgrant3830

Right off the top, the 1631C is going to stop you from starting. It saying the security password has not been learned in the system. Assuming the original BCM is toast, ok, but the new one needs the security relearn procedure performed then it needs to go to a dealer who can program in the RPO codes.

lucky131969

Ok, take a step back here. The BCM is not even reading the key...period....as supported by the B2721 code. The OP had/has this code (plus a B2722 and B2723 with the original BCM) with BOTH BCM's, which leads me to believe he may have changed out the BCM for a lock cylinder issue....that still exists....

Original BCM Codes:
PCM P1631 HC
BCM B0502 H
B0507 H
B2483 H
B2527 H
B2528 H
B2721 H
B2722 H
B2723 H
RFA U1000 H
U1064 H


Here are the codes with the new/used BCM:
PCM P1631 HC
SDM B1001 HC
BCM B2721 HC
A0-LDCM B2284 H
B2264 H
U1064 H
A1-RDCM B2285 H
U1064 H
B0-RFA U1000 H
U1064 H

LPDesRoche

Unless this lock cylinder issue just happened to show itself all of a sudden (which is entirely possible) I want to lean more towards the BCM getting wet issue. But then again, thats why i'm on here trying to figure it out

So what direction do you think I should go at this point??

lucky131969

First thing I would do is open the original BCM, and inspect for any water damage, corrosion, etc. Considering the codes you were getting for the key not being read for the BCM, I would start by reading the resistance at either the BCM or lock cylinder connector.

LPDesRoche

Ok when I get home tonight I will pull the radio bezel to get access to the lock cylinder wires. Which two wires do I measure the resistance over? My service manual is at a friends house so I have no schematics to go by.

Leeland

dgrant3830

So you are thinking the firmware/software reads the key "before" it checks the security password between the PCM and BCM? My thought was it did the password when the ignition first comes on and the key resistance was the last thing. I suppose it could be easily the other way around.

lucky131969

What I'm thinking is, the lock cylinder has to be known good or bad, before changing out a BCM.

lucky131969

If you PM me you email, I can send you the schematic. You can read the key resistance, right at the BCM.

dgrant3830

Oh I agree with you on that. I'm trying to understand why the PCM and BCM didn't share the security password which has to happen for things to work. Obviously the resistor in the key must also match what is stored in the BCM's memory but that's a seperate function from the security password. If the security relearn was not accomplished in the replacement BCM, I can understand it not starting but the original BCM, it should have matched but he's got the 1631 code in the original too which was having me question the BCM itself. I wish I knew the software sequence itself as that would help.

lucky131969

The BCM reads the key FIRST, then enables the TDR, and sends a message (via class 2) to the PCM, to enable the fuel injectors.

kh400

Did you disassemble the BCM from it's case and check for corrosion? Reason I ask is I had the exact same problem . Took apart the BCM and cleaned off the powdery corrosion with a soft toothbrush and wiped down with wd 40 on a paper towel, then wiped off again, then proceeded to use a hair dryer on it to make sure it was completely dry. Reassembled and reinstalled and problem solved. Just sayin. Good luck.

LPDesRoche

Pm sent. Thanks

dgrant3830

Lucky, I'm just trying to insure if I know how the system works therefore not incorrectly telling someone bad information from me. Here is what I'm going on out of the manual for my '99:


Its saying that the password and reading the key's resistor are two different functions. Yes, both work together of course but I can only assume they do this in order to prevent a thief from replacing the BCM to work with their key. Now reading the resistor, enabling the TDR and the command to the PCM to turn on the injectors, of course.

lucky131969

.....okay......and this is different the what I stated how?

dgrant3830

He's got two BCM's, the original and the replacement, both with the P1631C which I'm thinking implies he's lost the security programming of both and the reading of the key usually doesn't set the P1631 code if its just a bad read or bad contacts. Something else is going on here as well.

lucky131969

You must know something I don't. What caught my attention, is the fact that the OP had cylinder lock codes for BOTH BCM's. B2721, 22, 23. Perhaps I'm just barking up the wrong tree.....but...if it were my car(or one I was working on) I would make damn sure, the correct resistance was being read by the BCM consistently. My two cents....I'm out.