I have a 2004 Buick Le Sabre Custom , 3.8 V-6, Automatic transmission with approximately 55000 original miles. I had a remote start installed about 9 months ago, but, no other electrical modifications have been done. 3 days ago, I started the car, via remote start, & it started, but, when I tried to use the remote to unlock the door, it did nothing. I tried the original remote that came with the car, still nothing. Good thing I have a key lock. I shut off the car with the remote & entered the car like normal. After starting the car, I noticed the security light was on, (NOT blinking), along with the ABS, voltage, airbag & seat belt light. The speedometer works, but, the rear defrost , temp gauge, fuel gauge, radio & power door locks, ALL do not work. Neither of the remotes will unlock the doors or open the trunk. While the remote start remote will start the car, none of the other buttons work, (the lock, unlock & trunk buttons reply like they are working (2 way remote), but the relay in the car just clicks, the lights flash & nothing happens). The original remote gets NO response @ all. I replaced the batteries in BOTH remotes with no change.

Is there anybody with a similar problem or anyone who might have a suggestion as to what this could possibly be?

Thank you in advance, for any & all help with this issue. It will be greatly appreciated.

What'* the state of the battery?
Can you put a scan tool on it?

The battery is good. As far as the scan tool, I have an Autel AutoLink AL519 tool. I tried several times yesterday to get it to work, but, it would not link to the car. I have used this scan tool on this car in the past & had no problems. It always linked flawlessly.

I'd take it back to whoever installed the remote start. This is not normal behavior for a normal LeSabre. I believe it is significant that the aftermarket remote start works fine while everything else is broken.

What ^^^^ said.

I did not go anywhere over the weekend & now, Monday, 7 days after this started, the battery is dead.

Yeah, charge it then take it back to whoever installed it.

Thank you, both, for responding. Yesterday, I took the back seat out & disconnected the battery for about 2 minutes, connected it again, put my booster battery on it & the car fired up without a problem. Everything is working like nothing ever happened. Maybe resetting the battery is all it needed in the first place?? All I know is, it'* working again & I can get back & forth to work again. I will make the appointment with them now that it runs.Thanks, again, for the advice.

Cool!

I'm curious how this unfolds!

Turns out it was just a loose connection to the battery.