Electrical issues with 2002 Camry 2.4 ACV36R

[02 Ateva]

hey all,

in an earlier post I asked about an issue with the speedometer and the cruise control of my 2002 Camry 2.4 auto. Now that we have owned the car a bit longer, we have noticed a couple of things. Will try to describe it properly, sorry for the long post!

The car seems to have issues with the following electrical components:

- Alarm (factory fitted, not aftermarket):

The alarm will randomly go off for no reason. When it does that, there is no alarm code being displayed afterwards in the trip computer display when turning the ignition to ACC. Usually the alarm works fine, it goes off when you open a door from the inside after locking the car - and it will then display the correct code in the display once the ignition is turned on.

Whats weird is that it has never given a false alarm at home our at work. It does it however at random places like the shopping center car park our when going out for dinner!

- Radio (aftermarket Pioneer)

The radio will reset randomly. This happens roughly once a month, either over night or sometimes even when driving and listening to it. It will shut down and come back on with all stations and settings reset, just like the power has been cut for a second.

- Speedometer

Sometimes the speedometer needle appears to be twitching up and down once in a while even though the car is driving at a constant speed. It twitches up or down for about 1-2mm and jumps back 2-3 seconds later. If this happens while using cruise control, the cruise control will react to this and slightly accelerate or release throttle (depending on wether the needle twitched up or down from the current speed).

On a few occasions while waiting at a traffic light with the engine idle, the speedo will suddenly jump to 240 (or what ever the maximum is) and stay there twitching for a few seconds. When this happens the overspeed warning beeps constantly. The engine itself is not affected at all and revs nicely at idle. The speedo will go back to zero after a couple of seconds as if nothing happend.

After reprogramming the radio several times and cleaning raw eggs and nasty notes of it after the alarm upset the neighbourhood of our favorite restaurant I had a look at the wiring diagrams. I am not an expert when it comes to these diagrams but I did notice the radio, the instrument cluster and the alarm system are grounded to the same bar inside the dash. I looked at the ground points but they appear fine (tight and clean). I also disconnected the alarm horn permanently and when leaving the car somewhere we just unplug the main horn to prevent further egging...

Besides the aftermarket stereo the car is completely stock. I disconnected the battery during two weeks while being on a holiday, after that the car appeared to be fine for 2 weeks...then it all started again.

Has annyone experienced any issues like this with their Camry?