How do I reset the computer (brain box) on a 2003 Buick Rendevous

The ECM wouldn't have anything to do with the light's ! Electrical problem , connections at the battery , ignition switch problem maybe . trying to reset the computer won't do anything . Looking at power distribution diagrams , using a DMM - digital multi-meter to test electrical circuits , main power feeds to fuse boxes . Voltage drop test the main cables .

most modern locks require a under window lock release ,they use part of the lower window or a guard to block you from using a slim jim

This is not like an aftermarket alarm. It is built into the main computer and uses both the horn and the lights to sound a warning. The keyswitch has a reader and the ignition key must match the frequency recorded in the brain of the vehicle. It also kills the power to the starter and some even kill the ignition.

A shorted Battery will trigger the alarm, so have it fully tested. The reader and the wiring to the brain could also have a break in them, triggering the system. Sometimes worn ignition switches will lose contact with the key inside the switch.

The alarm is engineered to render the car immobile if tampered with. But a Dealer can Electronically recode a new Chip key to match

We just went through this with our 2003 Rendevous. Clicking like crazy but wouldn't start. Replaced the starter but still doing the same thing. Our next step was going to be replace the battery (which tested well) and the ignition assembly. Out of frustration, I hit the top of the hood and the headlights came on!! Further investigaton proved that the problem was a corroded ground wire on the battery. Hope this helps

remove the glove box - Buick Rendevous - 2003

Try changing the filter.

replace the drivers door courtesy light switch it is sticking and allowing the delayed exit module to keep the radio on, if you open the passenger door u will see the radio goes off.

Try pulling the wheel as far one direction as it will go in the locked position. Then while holding the wheel, turn the key. This has worked for me everytime (3x) I have experienced this.

i had the same problem with my 2003...it was # 32 fuse under the hood labeled front auxillary