AustinGard

My 93 ls400's factory alarm is acting up, keyless entry will lock the car but not unlock it. When I use the key manually in drivers or passengers door the alarm blares. I am not able to disable the security system so the car will not start due to the factory starter kill. I've researched this problem I'm having for hours and haven't found anything that worked someone please help me

dicer

The door lock switches are likely slightly corroded and that is why they won't let you in with out setting off the alarm. Part of its our wet state. Even with the alarm going off you should still be able to put the key in the ignition and cancel it. There have been write ups on here how to disable the alarm system. And for that matter if it is not the same on 93's and 4's as it is on the earlier ones, there is a way to do it since any aftermarket automotive electronics after market out fit does it all the time to install their own systems.

AustinGard

Thanks for the reply I also thought of the door switches but haven't done any digging yet. Is it possible for a bad door switch to affect remote entry? I can lock the car with the remote entry but will not unlock.

deanshark

I'm with dicer on being corroded. But it's a common problem with the key cylinder grease getting dirty. My 93 had a problem with the doors locking and unlocking on their own, over and over. Sometimes it killed the power so it wouldn't start. It never set the alarm (horn) off though. I would have to reset it by unlocking the passenger door two turns with the key. Then it would start. I never 100% fixed mine. I just sprayed PB Blaster into the lock but that only fixed it for a couple weeks, then I had to spray it again.
Also, I should mention I always used the key (not the remote) to lock and unlock b/c the remote would only work half the time.

dicer

There is nothing that you can spray into the lock that will reach the switch. The switch is separate from the lock cylinder.

deanshark

I know that. I was just saying I had some similar symptoms and it turned out being the cylinder. (my experience) But yes, the master switch can also be bad. It is another known problem with the 93-94.

Turning the key in passenger door to disarm the security system is actually 3 times to unlock position, not 2 times like I previously posted.

AustinGard

I checked the plastic cap looking peice that was attached to the key cylinder that makes the connection when the cylinder is turned to the lock/unlock position and it looked fine, no nasty corrosion or anything but I did see signs of wear from the the pins against the the inside of the "cap". I'm thinking there is a short in the wiring somewhere after the blue plug that these wires from the drivers door lead to. Where is the security system ecu located?

deanshark

I'm pretty sure it's on the inside of the firewall where the steering column goes through.

dicer

Ecu is inside the dash around the steering column if memory serves.
You will not find nasty corrosion, it is a skin that forms on the actual switch contacts, and to see them the switch needs to come out and be taken apart.