Oldfatty

Hello
The ear-splitting factory alarm on my 1998 LS400 has been going off inappropriately for a few months now. This usually happens just as I lock it, but not exclusively, or when I switch the engine off. It does not immobilise the vehicle (can be driven with the alarm still sounding) and can only be stopped by unplugging the battery. So far I have dialled down the proximity sensor underneath the centre armrest and changed the batteries in the fobs.

Since the alarm doesn't have any noticeable effect other than deafening me, my next move will probably be to find the siren and unplug it (not sure how this will go)

Any advice would be much appreciated
Thanks.

DerekD1010

iTrader: (1)

Could it be a defective key fob?

Yamae

Sounds like a MPX network body computer is malfunctioning. It is communicating with other computers and sensor switches. You need to find out which one is causing the problem but this is not easy because it needs some equipments and skills.

I'd check those switches first such as the food, the trunk and the key unlock warning switch. The next step is to check the communication with computers such as MPX network door computers and the key-less computer using a bus analyser since it uses a specially designed bus line called BEAN. If these are OK, the next step is to check inside of the MPX network body computer or simply to replace it if available.

timmy0tool

iTrader: (7)

hmmm is the alarm a siren or a horn sound? could it be possible you have an aftermarket system installed and is the one malfunctioning?
I don't recall an adjustable proximity sensor anywhere from the factory...