[Google mechanic]

I’m at a loss with this issue, my headlights,brake lights,tail lights, etc all work fine but my interior lights ( dash,radio,gear shifter, a/c controls) won’t work, my cluster works fine,I get my warning lights and so on but when it comes to driving at night there no way to see,the dimmer is not working but I’m assuming it’s because of fuse #12, any advice would be greatly appreciated

 

[1 Lucky Texan]

6 or 4 cylinder?

any chance you're running a rebuilt alternator? is the battery OK? dead cell or ????? battery cables good?

what is the charging voltage?

if it's very dark, and you look VERY carefully, can you see if the illumination control knob on the stalk makes even the slightest difference in dash lights when you turn it?

 

[cardoc]

 

[Google mechanic]

6 or 4 cylinder?

any chance you're running a rebuilt alternator? is the battery OK? dead cell or ????? battery cables good?

what is the charging voltage?

if it's very dark, and you look VERY carefully, can you see if the illumination control knob on the stalk makes even the slightest difference in dash lights when you turn it?

4 cylinder, alternator is not rebuilt, battery and cables are in perfect condition, the illumination stalk makes no difference at all

 

[plain OM]

Fuse #12 (cabin fuse panel) has power only when the Tail and Clearance Light relay is activated. The relay is activated only when the ignition switch is at On, and, the headlight switch is either at the parking lights, or the full headlight, position.

If fuse #12 blows when the headlight switch is turned to either light position, that indicates there's a short downstream of the fuse.

As @cardoc 's diagrams show, the fuse powers lighting in the cluster and various controls and switches inside the car, as well as the lighting control circuit of the "integrated module" (aka, "BIU").

Although it's not impossible, I would think it's not likely the BIU circuit has failed. More likely a wire going from the fuse to one of the bulbs, is shorting to ground.

Did this problem recently appear, but was fine earlier? Was any work at all done on the car between the last time the system worked properly, and when this problem was first noticed?

 

[Google mechanic]

Fuse #12 (cabin fuse panel) has power only when the Tail and Clearance Light relay is activated. The relay is activated only when the ignition switch is at On, and, the headlight switch is either at the parking lights, or the full headlight, position.

If fuse #12 blows when the headlight switch is turned to either light position, that indicates there's a short downstream of the fuse.

As @cardoc 's diagrams show, the fuse powers lighting in the cluster and various controls and switches inside the car, as well as the lighting control circuit of the "integrated module" (aka, "BIU").

Although it's not impossible, I would think it's not likely the BIU circuit has failed. More likely a wire going from the fuse to one of the bulbs, is shorting to ground.

Did this problem recently appear, but was fine earlier? Was any work at all done on the car between the last time the system worked properly, and when this problem was first noticed?

I bought the car second hand, so the lights never worked for me,it just became a problem the more I drove at night

 

[cardoc]

There's no definite answer. Too many bulbs on the circuit. Could be the cluster, down in the center console, a door, the radio, etc...........

 

[plain OM]

The 2004 Impreza was subject to the front passenger airbag recall. Go to Subaru Cars, Sedans, SUVs | Subaru of America, enter the car VIN, and see if the airbag recall was done (might have been done twice). I'm not sure if it's the same with the Impreza, but in the Outbacks, the work often involved significant disassembly of the dash area, and there's been problems due to improper reassembly.

Or, if a previous owner had put in aftermarket components or modifications, and removed them before selling, that could have led to miswiring or wires shorted to ground.

 

[1 Lucky Texan]

could this be a short in the body-to-hatch gaiter?

 

[plain OM]

I doubt it. Fuse #12 does not supply anything in, or related to, the hatch.