Security System security light is on in cabin and keyless entry does not work and the only way I can start it is by holding the key in the start position and pressing the unlock button on the remote. any suggestions would be helpfull.

I have had all of the above problems with my 2001 Monte Carlo for about 3 months. Idiot lights flashing, gauges not working, car not starting, radio locked. I was convinced it was the BCM and possibly the instrument cluster too, but didn't want to gamble hundreds of dollars on a "fix" that may not work. This afternoon, when the car wouldn't start and all of the gauges were dead, I turned the switch to "ON" and pulled the fuse for "CLUSTER/BCM" to the right of the relay for "retained accessory power", and then reinserted it. The gauges immediately came alive, the radio came on, and the car started on the first try. Just sayin'... might be worth a try for you. Also replace battery terminal bolts ($6) and check battery ground to frame. Mine briefly behaved better after servicing these items, but problems returned. The "fuse fix" however seems at present to be "permanent". The fuse wasn't bad... just apparently didn't have a really good connection, and the BCM is working now. There are two other fuses for BCM functions also. If you have problems with the heated seats not working (mine weren't) try pulling and reinserting the fuse for LH HTD seat/BCM. My heated seats immediately worked after that one. There's also one for PCM/BCM which, if you pull it while the engine is running will shut down the engine. Don't know if there are still issues with the BCM starting to "go bad", but everything is now working fine, with no idiot lights. Keeping my fingers crossed.

Several GM products, including the Chevrolet Impala and Malibu, the Oldsmobile Alero, the Pontiac Grand Prix, and Saturn Ion, have issues with the Security light coming on. This is many times an indication of a failing Body Control Module (BCM). Initially, the Security light will come on then go off, progressing to a constant on light, before the car will refuse to start. Other symptoms may include erratic action of electronics, a clicking sound coming from the glove box, and the air conditioning failing to blow cold air. I recommend a shop that specializes in the electronic systems of vehicles to diagnosis and make the necessary repairs. They should keep the car until they replicate the symptoms described. A new BCM from GM should cost about $230; plan on another $200 for them to diagnose the problem, replace the unit, and program the new unit. The dealers quote between $700 and $1,100 for the same repair. My experience and the experiences I have read on the internet, indicate the new BCM should last only about a year.