I have a 1994 LS 400 that did not have an owners manual when I purchased it. I have recently replaced the battery in the key remote but the remote still won't work. What do I need to do?

I had the same problem with a 98 remote so I went to Lexus and bought one of their remote batteries and had them install it...no more problems.

Your Security problem is most likely caused by a faulty ignition switch and passlock sensor.
The PCM and BCM will set DTC's to aid with the diagnosis of your problem.
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i agree with khooper,

IT could be youre immoblizer.. where after you replace youre batter remote it couldnt reconized.

suggest to go to lexus dealer to check & diagnosis the faulty...

Don't listen to Khopper and rockerfella, they don't know what they are talking about. A 94 LS does not have an immobliser system and there are hardly ever failures in the ignition circuit. No DTCs will be set because this OBD I system has only the very basic codes. Your most likely culprit is the key itself which happens fequently on this model. There is a test the dealer can do to check the signal. If it is, in fact, the key you would have to order a kit which includes two new keys and a ROM chip for the wireless ECU. Unfortunately, a new key cannot be programmed to this sstem. Sometimes you just have to bite the bullet and take it in.