Illumination Lighting problem

[chriskan]

Hi Guys,

Thought I'd post up here to see if anyone had any ideas. Just before the easter long weekend, the illumination lighting (interior) in the Lib died. it was strange. A couple of days earlier it blew the illum fuse, which I replaced and all was good. A couple of days later the lights went again, but this time the fuse was intact...

Anyway booked it into Subaru who suspect the illumn dimmer switch, which was replaced yesterday and problem still existed. Basically, when you turn the parkers or headlights on, no red lights on the switches or stereo. BUT when you turn the headlights off to the off position, the interior lights flicker quickly. The dimmer switch is also behaving strangely, it doesn't "dim" progressively anymore, but rather it's at full brightness or at full "dimmed" position.. nothing in between - this only dims the dash or the LCD screens on the stereo & clock. The dash btw dims correctly.

Yesterday Subaru GW (who have been great, trying to fix this) suspected it was the head unit and got new one in. I just got a call to say that didn't fix it either....

with my limited electronics background, I always suspected it was the dimmer switch, but since that didn't fix it.. I dont know!? I thought I'd post up here and see if anyone else experienced similar issues or had some idea as to what it could be.. coz Subaru are still looking!

Cheers

[Ric]

I have a few idea, will post back later tonight after I've looked in the 05 service manual to remond myself how Subaru do the dimming.

[chriskan]

Thanks Ric. Sam @ Glen Waverley has been great to deal with. He organised a new Outback for me as a loaner too! I honestly wasn't expecting this level of service!

[Ric]

Many traditional light dimmer systems connect one side of all the bulbs to ground, and vary the other voltage from 0V (off) to 12V (brightest).

The Subaru system works in reverse. When the lights are on, one wire is connected directly to 12V (purple wire), and the other wire (black with white stripe, or black with yellow stripe) is varied from 12V (off) to 0V (brightest).

The dimmer control does NOT directly control either wire.
The purple wire is switched by the headlight switch.
The black/white or black/yellow wire is controlled by the "Body Integrated Module".
All three wires from the dimmer control also connect only to the "Body Integrated Module", so if a new dimmer control didn't fix it, the problem is in the B.I.M. (which wouldn't be cheap!)

[chriskan]

Thanks Ric, I hope it gets sorted soon. It's under warranty - but I had a friend who had his honda's body control module replaced under warranty - cost was around 1200 for the part alone.

[chriskan]

Just got a call from Sam to say they've found the fault. It's the body control module Ric, as you correctly diagnosed

They've got one in Sydney and its on its way down hopefully next week. They swapped one out of another car there and verified it was the faulty part!

Cheers

[Ric]

Geeez, all those years drinking at the pubnext to the electrical engineering building at Melbourne Uni paid off.
(ok, I must admit I attended a few lectures too! )