Buick Rendezvous Security Light On

2003 Buick Rendezvous CX. Security light on the dash.
I checked all fuses and relays (all are fine). My car wont start. There are times when it will and times when it wont. When I put the key in the ignition, it acts like it will start (the gauges will all come on, you can hear relays working) but no crank over.

Sometimes when I am driving at night (happens during the day too) all lights inside and out of the car will shut down (all while the car is still in motion and running) as if I turned the car off. What can be going on with this Buick?

buick rendezvous

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The problems you are describing could be several different things. They could be related to each other or not. The engine not cranking could be a starter relay problem or the actual starter is going bad. But that would not explain the lights problem you have in your Buick.

These problems all could be related to a wiring problem in the fuse box that has the starter relay and other fuses in it. I would suggest removing a few fuses and relay's from the under hood box and look for corrosion. If water has gotten in there, you would see grime or green stains on the terminals. We have seen this problem several times before. Put a dab of di-electric grease on the terminals then re-install.

There could also be a problem with the theft system. If so, the Theft or Security light would either come on the dash or blink. A scan of computer codes would be needed to check for a theft problem.

For the lighting problem you have, this could be a BCM problem, or a faulty ignition switch. That could also explain it if you have a security problem as stated above, or not. An ignition switch is what feeds power to most of the vehicle systems. A problem with this can cause low voltage to the electrical components and make the lights go out like they are. You may also hearing some clicking in the dash.

The ignition switch can also cause all the problems you are having in your Buick. I would have that looked at first. Before taking it to a repair shop, start the truck and then tap on the head of the key and around the ignition with your hand or even a small hammer. Many times that will cause it to act up and you would see the lights flickering on and off. If that happens, have it replaced first, then drive it a while to see if it fixes all the problems you have with starting as well.

My 2002 Buick Rendezvous won't start (even when jumped...initially has charge till battery drained).Sometimes I put the key in, nothing happens. I remove the key, and you can hear relays going wild and gauges go in opposite direction. Is this an electrical short or bad Control Module or relay or something else? Thanks much!

This really sounds to me like a bad/shorted battery. Batteries can do some strange things in your Buick. The fact that when the key is in the ignition you get nothing, but when you remove it you hear allot going on is probably because of a low system voltage condition.

Modules, relays, switches on todays cars dont like a low voltage situation and cause them to act very odd. First check the battery connections are clean and tight. There is also a service bulletin about an under body wiring connector getting corroded.

It is under the truck, just behind about where the drivers seat is. The connector and harness go up to the floorboard. This connector gets corroded inside and can cause several electrical concerns.

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