Hi guys!

New member here and have been having a tough time trying to figure out why my 03 monte carlo wont start. Here is the story!

This whole mess started out with those pesky plastic heater hose elbows. Both of them blew up so I went to the parts store and bought the aluminum ones. When I got back I unhooked the battery and proceeded to disassemble everything to replace the elbows (belt, alternator, etc.). After replacing the elbows and putting everything back together I hooked the battery back up but when I tried to start the car I got nothing! All lights on dash and everything comes on but when I turn the key to start everything shuts off and nothing happens. After that I searched around and found these forums and tried just about everything that was suggested on here. Did the passlock relearn multiple times and nothing. Replaced the ignition switch and lock cylinder, needed it anyways, but still nothing. I also want to add that before replacing the ignition switch and lock cylinder the security light would come up on the dash and flash once but after it flashes 2-3 times. Also radio is displaying Cal Err and the fuses I have checked so far seem to be fine.

What could the problem be? Do I need a new BCM? Any help would be greatly appreciated! I am stumped on this one!

 

with that security light flashing id be investigating that. If that light is flashing the car isn't going to ever start up. its normal to come of briefly on startup but should go off. If it is flashing theres a problem. I'm assuming the car started before unhooking battery and replacing the elbows?
The last time I had to relearn a security light I think it took 30 or 40 mintues of turning the key of on and back off for it to reset.


Here is the official GM passlock relearn procedure:

1. Turn ON the ignition, with the engine OFF. Attempt to start the engine, then release the key to ON (vehicle will not start).
2. Observe the SECURITY light, after approximately 10 minutes the light will turn OFF.
3. Turn OFF the ignition and wait 5 seconds.
Turn key to START, sometime your car will start after only one relearn. If so, you're done. If not, repeat steps 1 to 3 two more times (for a total of 3 relearns). At that point, the vehicle will be ready to relearn the Passlock Sensor Data Code and/or passwords on the next ignition switch transition from OFF to START.
Important: The vehicle learns the Passlock Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.

hope this helps.

 

Thank you for the reply Aerocoupe86.

The car did start just fine before unhooking the battery and replacing the elbows. Thank you for your suggestion on the passlock relearn. Unfortunately I have tried multiple times and now my battery is dead because of it.

 

is it possible that the ignition switch went?

 

No Sir. As stated above, I replaced the ignition switch and the lock cylinder. Problem has to be something else as I still can't start the vehicle.

 

Anyone have any other ideas?

 

update:
got the battery charged up and did the 10 min relearn 3 times in a row and still no luck.

whole problem seems quite weird to me so I did some further looking and found this. traced some of the wires coming off of it and they seem to go into the passlock sensor, ignition switch, radio, possibly cluster, and maybe more.
Any one know what this is? Is this some sort of aftermarket alarm or bypass module?

 

I haven't seen that connector down there on mine, can't say

 

My daughter has an 03 MC SS as wel. Two weeks ago it would not start. She was at her dads so I couldn't do much but I thought maybe it was the battery. We had the battery checked and it was fine. I reinstalled it and the car started but the security light stayed one once I turned it off and started it again. I asked her if the security light had been on. She said yes.

So we did a relearn but different from the one you posted.

You get in the car and turn the key to acc. Then get out locking the door. Shut the door and unlock with the key.

Get back in close the door, turn the key to acc and turn the headlights on and off 3 times.

Then turn the key to off. Then try to restart. The security light didn't come back on.

Now, her trunk release and power locks keep blowing fuses. And I keep having to do the relearn I mentioned due to the security light but it starts after that!

I think I need to check her BCM connections if not replace the bcm. But I'll try everything else first!

Maybe this will help you.

 

mandy1700, I have tried that relearn procedure as well and unfortunately it did nothing for me.

Update
I looked more into that weird connector in the picture above and found that it had 3 wires grounded and then someone had cut the yellow wire going to the ignition switch and had this connect hooked up in-line. I looked up a schematic for 03 monte carlo ignition switch and this yellow wire is labeled "starter wire" so I thought that I was finally getting somewhere. I removed this weird connector and reconnected the yellow wire with a heat shrink connector. I tried starting the car and still nothing!

Security light doesn't flash 3 times anymore but just comes on once and goes to CEL.

Please, if anyone can help or give me some sort of direction to go in with this I would greatly appreciate it!