Weird Electrical Problems On Gs300 - Help!

[srosenman]

MY BATTERY IS FAIRLY NEW BUT HERE IS WHAT IS HAPPENING...

Headlights do not turn on when i switch them to on position but then they work when i switch them to off position. I had to pull the fuse to prevent battery from going dead ... because even when the headlights turned themselves off (when the switch was in the on position due to this malfunction) the interior lights stayed on.

Then after I pulled interio lights fuse, approx. 10 minutes later the horn started to run constantly until i had to pull that fuse....

PLEASE HELP.

It rained hard today, otherwise car has no water damage history...

[GuyTelefunken]

I'd start with a "hard reset." Disconnect the negative battery cable for a few minutes and the reconnect. Confirm that the interior lights go out with the doors closed. The red "door-open" indicator in the instrument cluster should be off with all the doors closed. If it is, that rules out the auto-off headlight timer circuit which turnes off the headlights after X-minutes of all the doors being closed.

The horn honking alarm may be related to a door switch failure which also may relate to the headlight operation.

Let us know what happens and we'll take it from there.

BTW, what year car do you have? Hint, put it in your profile!

[srosenman]

i have a 1998 gs300. lexus replaced the multiplex computer (part no. 89226-30030). 5 hours of labor and part cost $1000.

car works fine now.

[GuyTelefunken]

Wow, glad it's fixed. Part No. 89226-30030 has an MSRP of 456.60. Labor must be about $96.00/hour in NJ. I've got to raise my prices!