Hello there everybody, I would just like to thank you for your time reading this.
I have a 2000 Chevy Cavalier, 2.4L.
Keyless Entry problem:
Alright about 2 weeks ago my keyless entry started acting funny. I press unlock once...it unlocks drivers door....twice and nothing. I press lock once....nothing....twice it sets alarm. Trunk works fine and I can set off panic just fine.
I was told to try having my key fob reprogrammed so I did that...nothing. That same day the mechanic working on my car told me that it was not the BCM that it was working properly and that it was the relay....so I replace that....nothing. So I take it back to the dealership and go through a different mechanic who tells me that it is in fact the BCM that is failing.
So I don't know who to believe or what to do since that BCM is of course being the main computer, $200.
I also thought that maybe it was the driver door locks actuator. But I don't know if this could be the cause or not.
Brake Light problem:
Around the same time that the keyless entry started acting funny, so did the brake lights. My aunt was following me one day and informed me that my two main brake lights were't working...only the cyclops light was. So I checked all the fuses and everything and they were all fine. I replaced the bulbs and they were all fine. My parking lights also work fine, along with the reverse lights. Now, they aren't always out. Most often they are working fine.
The dealership informed me that it was the sockets...so $150 for sockets and diagnostics the problem still isn't fixed and the dealership tells me now that there isn't a way for them to figure out the problem because they work most of the time.
I have heard that it might be the turn signal switch and I purchased one but have not installed it for fear that the airbag will deploy on me since I have to take apart the whole kit and kaboodle. I was told by a mechanic that even though he disconnected all the wiring and battery and fuse that two airbags in the cavaliers have still deployed on him working in the vicinity.
Sorry this post was so long and I really do appreciate your input. Hopefully, somebody here can give me some insight. Thanks!!!!
Okay lets start here.
First off the airbags wont deploy on you as long you safely remove power from them. You disconnect B- and wait 20 minutes, back up supply is now drained and they wont deploy, no matter what.
If your Body Control Module is bad, it will show up using a scan tool. I have seen then fail internally, where they dont communicate with the other control modules. At least on Nissan scan tools you can make the BCM do certain functions, and make it talk to other modules, if it doesnt do what you request, or doesnt talk to other modules, than it is bad.
If your turn signal switch is bad, it will be no turn signals all the time. A switch doesnt fail intermittley, however connections do come and go. A switch can be tested easily, simply if there 12V to it, and 12V from the oppisite side of it.
If your brake light switch was bad, you would have no brake, not just the center one so that is out to.
Now I would recheck your brake light fuse. A would confirm, you have 12V at the lights, I would confirm you have a ground.
Also the BCM doesnt control, the brake lights, the LCM, lighting control module does all that.
Your keyless entry problem could be an internal BCM failure.
- 2004 Cavalier - 124k, owned since new
J-cars don't use a lighting control module. The BCM does have inputs from the various switches... ebrake, headlights, etc... but it doesn't control them (it uses the inputs to control the DRLs though).
It sounds like the BCM is shot to me. I've killed one, it's really common in some Cadillacs where its behind the back seat. BCM's are cheap and plentiful at the wrecking yards... just get one from a car with the same options as your car, and you'll need to do the 30 minute PASSLOCK relearn as described in the Library FAQ.
Rob S wrote:Okay lets start here.
First off the airbags wont deploy on you as long you safely remove power from them. You disconnect B- and wait 20 minutes, back up supply is now drained and they wont deploy, no matter what.
If your Body Control Module is bad, it will show up using a scan tool. I have seen then fail internally, where they dont communicate with the other control modules. At least on Nissan scan tools you can make the BCM do certain functions, and make it talk to other modules, if it doesnt do what you request, or doesnt talk to other modules, than it is bad.
If your turn signal switch is bad, it will be no turn signals all the time. A switch doesnt fail intermittley, however connections do come and go. A switch can be tested easily, simply if there 12V to it, and 12V from the oppisite side of it.
If your brake light switch was bad, you would have no brake, not just the center one so that is out to.
Now I would recheck your brake light fuse. A would confirm, you have 12V at the lights, I would confirm you have a ground.
Also the BCM doesnt control, the brake lights, the LCM, lighting control module does all that.
Your keyless entry problem could be an internal BCM failure.
I have had two different techs at the dealership that have scanned my BCM. The first one said that it was working properly and that the reason for the keyless issue was the relay, which I then replaced, and that wasn't the cause as it didn't fix it. So, I took it back and the next guy said that he scanned the BCM and that it wasn't working properly and that was the problem that would fix the issue.
My question is before I fix that, could it be the driver's door actuator...from the wiring diagram it looks like the driver's door actuator controls the other 3 doors....just an idea before I spend the $200 to fix the BCM.
Also, I know that the turn signal switch doesn't CONTROL the brake lights, but the wires for the two tail brake lights run through the switch. The dealership said the next time they go out try flipping the hazard switch a couple times...if that brings them back up then that confirms that you have some short or an open circuit within the turn signal switch. So that's what made me think to replace that. Let me know what you think.
I appreciate your response....and hope to get another :-)!
Thanks!
John Lenko wrote:J-cars don't use a lighting control module. The BCM does have inputs from the various switches... ebrake, headlights, etc... but it doesn't control them (it uses the inputs to control the DRLs though).
It sounds like the BCM is shot to me. I've killed one, it's really common in some Cadillacs where its behind the back seat. BCM's are cheap and plentiful at the wrecking yards... just get one from a car with the same options as your car, and you'll need to do the 30 minute PASSLOCK relearn as described in the Library FAQ.
Yeah the 30 minute passlock is using the tech 2. That's what I had them do to start with since I was told that sometimes when the batteries get too low in the remote, when you replace them sometimes the codes scramble. I never thought about a junkyard....I might try that. Do you know if I need a BCM from my actual year? Or could I possibly, or shall I say hopefully find one from a newer (than 2000) model that has less wear on it?
Thanks for your response....hope to hear from you soon!
Okay I dont know the wiring of your car. It sounds logical that the brake lights are wired through the turn signal switch. I have worked with that for a while, although I consider myself ot be good with eletrical work, other people are better than me at all.
I would assume with your BCM, you would need it for your year. I would see how much the dealer wants for the part, he will most likely want your VIN to.
- 2004 Cavalier - 124k, owned since new
If your car is a 2000, you'll need the 2000 (or possibly 01 and maybe 02) BCM... you need the same options... ie if your car is a Z24, look for a Z24 or LS 4 door.... so you'll have the 2.4L... and the A/C... and the keyless entry....
Look at your BCM before you go... you want the same part number, with the RFA letters on it (that's for the keyless entry). If you get a 2.2L w/o a/c, your a/c won't work anymore..
Here's the kicker... your mileage is going to change. It will be whatever the new BCM is... that's where milage is stored on the 00-05 cars. Make sure to find one close to yours, and note what the difference in mileage actually is.
The brake light switch (white wire) feeds to the turn signal switch, which combines the brake/signal light wires (yellow and green) which run to the tail lights. If there's a problem with the switch, it can cause what you described. Again... junkyard or wrecker... the switch is close to $100 at the dealer... assuming you have cruise control. I get them for $20 at the wreckers here... get one from an 05, so you know it's newer...
You can do a 30 minute relearn without the Tech 2... it's just turn the key to on, let it blink for 10 minutes, then off, repeat two more times. Then off, then start the car up. The instructions are in the FAQ. You can do it faster than 30 minutes with the Techlink terminal and downloading the R-code from the GM computer... but most people don't have access to that
