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2004 subaru impreza outback Automatic Japan made
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Discussion Starter · #1 ·
The title covers it pretty well,I just purchased a 2004 impreza outback and I noticed that the lights on the gauges and a/c controls do not light up,I've tried swapping the bulbs and swapping the dimmer arm to no avail,I've searched everywhere for a solution. I just wanna enjoy this car at night
 

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Are the headlights, tail lights and marker lights coming on with the headlights switch turned on? Reason I ask is some people believed the headlights were coming on when it was actually running the DRLs, daytime running lamps.

Fuse 11 under the hood is for lighting. Fuses 12 and 13 in the interior fuse box controls the combo switch and interior illumination. Fuse 5 is the tail lights. Check these first. Check that all the lights on the car function, DRL and lights with the headlamp switch in all positions. Check the operation of the Park Light switch with the headlight switch OFF.

The ground circuit for the lights comes from the integrated unit, black box under the dashboard behind fuse box.

The "Tail/Illumination Relay", behind the interior fuse box, gets power from fuse 7 in the engine compartment. With the relay energized it sends power to fuse 5. So with the lights on, fuse 5 should have power. The T/I relay gets power from the IGN Switch and ground from the headlight switch to energize it.

Fuse 12, as seen in the diagram attached, is to the gearshift lighting, lights for the fog and cruise switches, and they all share the ground from the BIU. Radio illumination is also on the same circuits, but I assume it may be aftermarket. If it's OEM then the radio lighting is also on the same circuits and should change with the headlamp dimmer switch.

The wiring diagram pic is giving me issues when I try to post it. I'll figure that out later. For now try downloading the pdf attachment.

Power to the interior light control goes through the instrument cluster. Grounds for the lights come from the BIU. Easy way to check this is to pull a switch on that circuit, cruise, fog lights, hazard, and check their power and grounds. If you have power, then it's getting through the cluster. If you have ground, it's coming from the BIU. If you are missing either, then you have to check the circuits on the cluster or BIU.

The cluster has had issues, varying, on the Impreza way back to the 90s models. Solder joints crack or resistors burn out.

This is the Hazard switch pin assignment. Power to 5, Ground on 2.
1605527783244.png
 

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2004 subaru impreza outback Automatic Japan made
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Discussion Starter · #4 ·
Are the headlights, tail lights and marker lights coming on with the headlights switch turned on? Reason I ask is some people believed the headlights were coming on when it was actually running the DRLs, daytime running lamps.

Fuse 11 under the hood is for lighting. Fuses 12 and 13 in the interior fuse box controls the combo switch and interior illumination. Fuse 5 is the tail lights. Check these first. Check that all the lights on the car function, DRL and lights with the headlamp switch in all positions. Check the operation of the Park Light switch with the headlight switch OFF.

The ground circuit for the lights comes from the integrated unit, black box under the dashboard behind fuse box.

The "Tail/Illumination Relay", behind the interior fuse box, gets power from fuse 7 in the engine compartment. With the relay energized it sends power to fuse 5. So with the lights on, fuse 5 should have power. The T/I relay gets power from the IGN Switch and ground from the headlight switch to energize it.

Fuse 12, as seen in the diagram attached, is to the gearshift lighting, lights for the fog and cruise switches, and they all share the ground from the BIU. Radio illumination is also on the same circuits, but I assume it may be aftermarket. If it's OEM then the radio lighting is also on the same circuits and should change with the headlamp dimmer switch.

The wiring diagram pic is giving me issues when I try to post it. I'll figure that out later. For now try downloading the pdf attachment.

Power to the interior light control goes through the instrument cluster. Grounds for the lights come from the BIU. Easy way to check this is to pull a switch on that circuit, cruise, fog lights, hazard, and check their power and grounds. If you have power, then it's getting through the cluster. If you have ground, it's coming from the BIU. If you are missing either, then you have to check the circuits on the cluster or BIU.

The cluster has had issues, varying, on the Impreza way back to the 90s models. Solder joints crack or resistors burn out.

This is the Hazard switch pin assignment. Power to 5, Ground on 2.
View attachment 497441
I just noticed my gear shift wasn't lightning up either,all my lights seem to turn with their respective switches,I'm not sure if drl is supposed to turn on any lights in the front because mine didn't,do you think ill have to swap my BIU?
 

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You mean the DRLs are not working? The DRLs come on with the engine running and park brake off.

Lighting; fuse 16 gives power to the DRL relay and High beam relay. Do your high beams work? Either with the headlamps on or flash to pass?

Keep in mind here that the switches control the GROUND. Without good grounds the switches, modules and relays don't work proper. A weak ground will reduce the available current flow.

497448


BIU power system

497446


497447
 

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Discussion Starter · #6 ·
You mean the DRLs are not working? The DRLs come on with the engine running and park brake off.

Lighting; fuse 16 gives power to the DRL relay and High beam relay. Do your high beams work? Either with the headlamps on or flash to pass?

Keep in mind here that the switches control the GROUND. Without good grounds the switches, modules and relays don't work proper. A weak ground will reduce the available current flow.

View attachment 497448

BIU power system

View attachment 497446

View attachment 497447
Ah,that makes sense I confused them with my low beam switch, but yes, my high beams and drl are all working fine,my turn signals flash with no issue
 

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I noticed that the lights on the gauges and a/c controls do not light up,I've tried swapping the bulbs and swapping the dimmer arm to no avail,
The wiring diagram attached to post #2 above shows all the interior instrument panel and dashboard controls that should be lit when the ignition is at ON (engine need not be running) and the headlight switch is set to its first position from Off, i.e., it will be in the "parking lights" position. These are along the right side and bottom of the diagram. Look at the diagram and check each one in the car to see if it's working.

In addition, with the ignition and headlight switches as above, outside at the front of the car there should be two amber clearance lights on (one at each corner, and at the back, two red tail lights and white lights over the license plate. Check them.

Let us know which ones are working, and which are not. This will help narrow down the area of the problem.

If it turns out all the exterior parking lights are working, but none of the gauges and dashboard control lights are working, then fuse #12 in the cabin fuse box should be checked.

@cardoc Not my intent to highjack; just want to go back to results of your suggestions in post #2 above.
 

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Sorry just got out of work,my drl are running fine,and I swapped fuse 12 when I got the vehicle suspecting that was the cause
Okay, so not fuse #12. Let us know which lights are, and are not, working. That will hopefully narrow down the multiple circuits in the wiring diagrams.
 

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Discussion Starter · #12 ·
Okay, so not fuse #12. Let us know which lights are, and are not, working. That will hopefully narrow down the multiple circuits in the wiring diagrams.
All exterior lights are working, the only lights that are not working are the ones that make my speedometer,tachometer,A/C control, and gear stick glow. My instrument cluster will still show things like open door and high beams etc,the only things it fails to glow are what I listed
 

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All exterior lights are working, the only lights that are not working are the ones that make my speedometer,tachometer,A/C control, and gear stick glow. My instrument cluster will still show things like open door and high beams etc,the only things it fails to glow are what I listed
If the exterior parking lights work when the ignition is at On and the headlight switch is at the first, parking lights, position, that confirms the tail & illumination relay, and its power supply.

When the ignition is at On, and the headlight switch is in the second (parking lights) or third (headlights) position, is the clock on, and when the glove compartment door is opened, is the small light inside on?

[In the wiring diagram, the brightness of most of the bulbs, e.g., for the instrument panel and the HVAC controls, can be changed using the variable control on the dimmer, but the clock and the glove compartment lights are not variable; they are either on or off. By checking if they work, we can verify the power coming from fuse #12, and the grounds for those bulbs.]

If they do not work, then it points back to fuse #12. It should be checked again. If there's a short, it might have blown after it was replaced.

If they do work, then the "integrated module" could be faulty.

497516
 

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Discussion Starter · #14 ·
If the exterior parking lights work when the ignition is at On and the headlight switch is at the first, parking lights, position, that confirms the tail & illumination relay, and its power supply.

When the ignition is at On, and the headlight switch is in the second (parking lights) or third (headlights) position, is the clock on, and when the glove compartment door is opened, is the small light inside on?

[In the wiring diagram, the brightness of most of the bulbs, e.g., for the instrument panel and the HVAC controls, can be changed using the variable control on the dimmer, but the clock and the glove compartment lights are not variable; they are either on or off. By checking if they work, we can verify the power coming from fuse #12, and the grounds for those bulbs.]

If they do not work, then it points back to fuse #12. It should be checked again. If there's a short, it might have blown after it was replaced.

If they do work, then the "integrated module" could be faulty.
The clock is on, I didn't know there was a small light in the glove box so I'm guessing that's not turning on either, ill switch our the fuses again and see if that does anything
 

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The clock is on, I didn't know there was a small light in the glove box so I'm guessing that's not turning on either, ill switch our the fuses again and see if that does anything
First thought, but let's not go on guesses. Check the glove compartment bulb, or just replace it and see if it works. As mentioned, if the clock and glove compartment lighting works then the module is the more likely suspect. (The 2004 Owners Manual refers to the module as the "Illumination brightness control".)
 

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Discussion Starter · #16 ·
First thought, but let's not go on guesses. Check the glove compartment bulb, or just replace it and see if it works. As mentioned, if the clock and glove compartment lighting works then the module is the more likely suspect. (The 2004 Owners Manual refers to the module as the "Illumination brightness control".)
Just checked, there's a little light in there that isn't turning on
 

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The clock, accessories outlet and the glove box light are on the same power circuit, just different grounds. So if the clock is working, the glove box bulb is either bad or it's disconnected. No telling if someone's been in there and neglected to reconnect it after removing the glove box for cabin filter or other work.

Does the accessory socket work? Can you plug something in to it and check?

This is looking like the BIU is not sending a ground to the other lights. You would need to check the circuit at the connector. You can use a simple test light with the light's cable connected to a power source, something at the fuse box or run an "extension" to the positive post on the battery, and the probe end in the connector off the BIU; pin 14 of B280. When you turn the lights on you should have a lit test light if there is a ground coming out of the module.
 

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Discussion Starter · #18 ·
The clock, accessories outlet and the glove box light are on the same power circuit, just different grounds. So if the clock is working, the glove box bulb is either bad or it's disconnected. No telling if someone's been in there and neglected to reconnect it after removing the glove box for cabin filter or other work.

Does the accessory socket work? Can you plug something in to it and check?

This is looking like the BIU is not sending a ground to the other lights. You would need to check the circuit at the connector. You can use a simple test light with the light's cable connected to a power source, something at the fuse box or run an "extension" to the positive post on the battery, and the probe end in the connector off the BIU; pin 14 of B280. When you turn the lights on you should have a lit test light if there is a ground coming out of the module.
Accessory socket works fine, I work at a junkyard so ill just pull a biu and hope for the best
 

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Does the accessory socket work? Can you plug something in to it and check?
The accessory socket in the wiring diagram is there only for the small light that shows its location. The power for the socket itself is not part of the lighting system. The socket might power something that is plugged in (as is the case), but the light might not work. It's the light that is part of the lighting circuit that has a problem.

Accessory socket works fine, I work at a junkyard so ill just pull a biu and hope for the best
That's the place to be in these cases!
 

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Discussion Starter · #20 ·
The clock, accessories outlet and the glove box light are on the same power circuit, just different grounds. So if the clock is working, the glove box bulb is either bad or it's disconnected. No telling if someone's been in there and neglected to reconnect it after removing the glove box for cabin filter or other work.

Does the accessory socket work? Can you plug something in to it and check?

This is looking like the BIU is not sending a ground to the other lights. You would need to check the circuit at the connector. You can use a simple test light with the light's cable connected to a power source, something at the fuse box or run an "extension" to the positive post on the battery, and the probe end in the connector off the BIU; pin 14 of B280. When you turn the lights on you should have a lit test light if there is a ground coming out of the module.
Just swapped the biu and replaced the fuses,the lights still won't come on, this is slowly becoming a headache.
 
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