I am buying a 1999 RX300 from a friend and he told me that when the outside temperature gets to high and his alarm goes off. Why would this happen and what can i do to fix this? He took it to Best Buy and they could not help him. Please help if anyone knows. thanks

John

 

Is it the factory alarm or after market (Best Buy)?

All electronic equipment are affected by temprature. Culprit could be one of the sensors (they monitor minute changes) and then it could be the main unit.

Salim

 

Thanks for your response. It is the factory alarm that came with it from Lexus. What sensor(s) do you think it could be for me to look at or change??? Is there a way to discount the alarm? I would rather just fix it but need some help. Thanks

 

I have not seen factory alarm problems posted here. I myself have very limited insight into the factory alarm .. other than commenting on porbable cause of elctronic equipment malfunction.

Your best bet to get a decent diagnosis done would be the dealership. They have the equipment to read various sensors and get your car back on the road quickly.

Do let us know what they find out.

Salim

 

I will let you know.

 

How long has the RX alarm been doing this? Like Salim, I've had no direct experience with the alarm itself, but on a well-seasoned car like this there are a couple of things that could be suspect. The outside temp may only be a coincidence, or a secondary contributor - keep looking. What other factors come into play at high OAT?

I had a Suburban with a complex aftermarket alarm that would occasionally trip at the strangest times - the worst was while driving in freeway traffic. The cause was eventually traced to dry-fit electrical connections in the steering column (a factory defect, they are all supposed to have a coat of grease to prevent corrosion). Corrosion produced intermittent contacts and a raft of strange problems. The alarm processor read this as "tampering" with the electrical system and sounded off. Naturally GM denied all knowledge and I was on my own to fix it. A few hundred bucks later, after having the steering column pulled and over 25 connections cleaned and properly greased, all was well.

The second thing that comes to mind is the old RX catch-all, a failing battery. The RX's complex electrical system can exhibit all kinds of strange behavior as the battery is in its death throes: odd displays on the information screen, failure of some electronic functions - the list is a long one. You might get the battery checked out with a test under load (free at AutoZone and other shops) to see if you have an internal problem in the battery. Your RX is coming up on 7 years of service and if it hasn't been replaced already, it's more than due.

Keep us informed!

 

Thanks Lil4X. I had a electrician tell me something like that also at my work. All input helps me on this. Thanks again for your time and help!

 

I talked to my friend and he said that the battery was changed bout a year ago. So i am trying to rule out the battery. He said that the only thing that is a factor is the OAT. Thanks for any help someone can give me.