Hello, this is my first post but have been reading for quite a while gaining valuable info from all of you. Well now I have one I can't figure out and need some help.

To start I have a 2002 QC 4x4 4.7, and among many tune-up items and a few mods since I bought it last fall I decided to replace the o2 sensor. Got that done ok, including unhooking the negative cable off the battery to reset the computer while I was doing it. When I go to put the cable back on the factory alarm goes off. I have tried every way I can find for disarming it, the only thing that works is to unhook the cable again to get it to shut up.'

I have tried unlocking with the Fob, hitting the panic on the Fob, putting the key in both doors to lock/unlock in various combos, set the key in the ignition, tried to start it, etc. Any ideas guys? It won't start because the security feature has been activated. Is there something under the dash I can unplug? I couldn't see a fuse labeled "alarm".

Help!

 

now that's odd. I've not had that problem.

Is your truck a gray or black key? I'm guessing gray? I can't imagine why, but the computer may have somehow "forgot" the code for your key(s)

 

It has a black key. I know, that is what it seems like, it doesn't recognize that I am using the key for it at all. I am going to try a few more times today, just to see if it will magically work and too annoy the neighbors some more.

 

I had a weird problem like this in my grand prix.

Have you tried sitting in your truck and manually locking all the doors? Then using the key fob to unlock them?

 

Well, I tried that with the doors all locked manually, attached the cable and the FOB didn't seem to do anything, so I thought maybe I need new batteries. So I run and grab new ones, try it again and still doesn't seem to work, but I got in put the key in the ignition and went back and forth from start back to accessory a few times. The good news is the alarm seems to have disarmed, but now the truck won't start.

When I crank the key forward all the lights and warning bells come on, but no crank, no clicking, no nothing. Same for my spare key that is not the chip kind, just a plain metal one. So now what? Any ideas?

Could my battery be bad? The radio works fine, windows go up and down like normal, doesn't seem like it would be the battery. Only other thing I can think of is its a security issue that I'll probably need to tow it to the dealer for? Ugh, I hope not...

 

Okay, nevermind, back to square one. I went out to try again just for the heck of it and right back to where I was, alarm blaring and nothing working. Apparently I just got the alarm to silence before, nothing more. I guess I will call the dealer in the morning unless someone else has an idea.

 

It may be a bad Central Timer Module. Maybe unplug it and let it sit for a few minutes, see if it resets. CTM is the body control module for your truck, and is located behind the driver's kick panel. Pull the kick panel piece straight toward the back of the truck, it only has plastic clips holding it in place. When you remove the plastic kick panel trim piece you will see a small black box with 3 plugs and about 80 wires going to it. Unplug those 3 plugs, let it sit a few minutes, plug it back in and see whether the truck starts and alarm is OK. It may not work but is worth a try. The factory alarm is an internal part of the CTM. Since you do not have an immobilizer ignition system it might be good to check the CTM first. If you are taking the truck to the dealer they will be able to tell you for sure if the CTM is bad, the dealer can check it with the DRB3 scan tool. If you have to buy a new CTM, the dealer can also use the DRB to program both of your original keyless entry remote controls to operate the keyless/alarm system.

Jimmy

 

Thanks for the reply, rode the bike to work today so I'll try that when I get home. If it does turn out to be the CTM do I have to buy that from the dealer? I read the thread on here about that being the source of other problems, and some debate on whether or not to buy that new or look for one from a junk yard. On something like that I would probably lean toward new just because it is electronics in nature, but what do you think?

 

i may be way out in left field on this, but are you sure it is a factory alarm? there could be an aftermarket one in there and you didnt get the remotes when you bought the truck. i see that all the time with used cars. take a look under the column to see if there is an alarm box up there tied into your factory ignition and starter wires. is it the horn honking or a siren?

 

If there is no aftermarket alarm, I think it is best to buy a new CTM if you need one, it is sensitive electronic part and you may not be able to trust a used one or even get a used one to work. The dealer uses your VIN to order the correct CTM for your truck.

It is a good idea to check for an aftermarket alarm too. If it is aftermarket, you may have a failed starter kill relay. Any good car audio shop could help you with that.

Jimmy