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Discussion Starter #1
So, I swapped out my heater core successfully on my 2003 Subaru Outback 2.5l and now my power windows & power seats don't work.

After completing the heater core swap, I put the dash back together and there were a few circuits that didn't work. After finding a plug or two that were missed, I had everything working except for power windows, power seats and the back light on the instrument cluster. I searched in vain for more missing plugs and then noticed that there were two fuses blown. I swapped them both and the one is fine, while the other blew again (Dash Fuse 12 - backlight for the IC) when I restarted the car.

I checked hard for buggered wires and obvious faults, but most of the wires are bundled and I didn't see anything near a bolt or pinch point. Does anybody have advice for how to quickly narrow down where to find a short somewhere in the wiring harness behind the dash?

I have access to the wiring diagrams, although my head is hurting trying to figure out how to use them. I have noticed that everything not working has some related wires, but I'll have to study the schematics harder tomorrow.

Also, I guess I should mention that since the fuse has blown and sparked I have worked under the assumption that I have a pinched wire somewhere with a short to ground. If anybody else has a better theory, I'm open to ideas. I'm not looking forward to this, but it looks like I've got my weekend taking up with tracking down this problem.

Thanks for any help,
-Jon
 

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I had everything working except for power windows, power seats and the back light on the instrument cluster. I searched in vain for more missing plugs and then noticed that there were two fuses blown. I swapped them both and the one is fine, while the other blew again (Dash Fuse 12 - backlight for the IC) when I restarted the car.
Are the power windows and power seats working now? (They share a slow blow fuse in the main fuse box in the engine compartment, and a circuit breaker. The fuse is SBF-6, 30 Amps.)

Dash fuse #12 (in the fuse panel to the left of the steering column) goes to a large number of loads. The fuse is shown on page WI-19 of the wiring diagram. (Page #s are from my 2003, Subaru of America wiring diagram.) It gets it's power through the Tail & Illumination Relay, which is energized only when the ignition key is at ON (even with the engine not started).

From fuse #12, the power goes to FB-26 and FB-27. (These are just identifiers of circuits -- a way to move from page to page in the wiring diagrams without having to draw lines all the way.)

Fuse #12 provides power not only to the combination meter back lighting (through FB-27), but also the lights in most of the dash panel controls and switches. (See page WI-148). So, presumably, all of these lights are not working as well.

The devices powered by these circuits are listed on pages WI-21 and WI-22 and include the following (some might vary with car model):

AT select lever illumination light
Integrated module
OP connector
Power window main switch
Seat heater switch

and

Audio
Auto A/C control module
Ashtray illumination light
Baja light switch
CD illumination light
Cigar lighter illumination light
Combination meter
Cruise control main switch
Front fog switch
Globe box light
Hazard switch
Manual A/C control module
VDC off switch
Wiper deicer switch

A number of these would have been moved, disconnected, or disturbed in some way during the heater work. It's less likely that a whole wire bundle was pinched, but a single or unwrapped wire might well have been. It's also possible that a connector to one of these was either reconnected improperly (some can be inserted two ways if the guide pin is broken, or by forcing), or to the wrong mating connector (the latter is less likely but not impossible) and is causing the short. There's also the possibility that one of the devices developed an internal short during the work, but again I'd think that's less likely.

Unfortunately, I don't know of any way to isolate the fault without taking a step-by-step elimination process. Some of the devices, such as the radio, combination meter, heater/AC control panel, and some of the switches, can be disconnected to eliminate them as a cause. Others will require tracing the wires to verify that the connectors are on properly and that none of the exposed wires (as opposed to those in a taped bundle), typically nearer the connectors, are pinched or frayed and contacting a ground point.

Do you have a digital multi-meter with a resistance range that has an audio tone? This function can sometimes be helpful in finding a wire that is grounded. If the wire is frayed and touching, if it's moved the ground connection could be broken. But where is it? With the meter connected between the un-powered side of fuse #12 and ground (fuse out) there will be a low resistance (enough to blow the fuse) and the audio tone will sound. Now, without looking at the meter, the wires under the dash can be moved by hand, one by one (as much as this is possible). If there is a grounded wire that is not mechanically pinched, the tone might go off when the wire is moved, thereby identifying the wire, or at least the wire bundle where the short is located. Similarly, disconnecting devices, such as the radio, one by one and listening for the tone to go off could isolate a component that is shorted.

Incidentally, on Page WI-146, we see that FB-26 supplies to a number of lights, but is also goes to the "OP Connector". This is a 15 pin, natural-colored or white, connector that is used for diagnostics, but is not otherwise connected to anything. If it was inadvertently connected to another connector, that could be shorting the circuit. I believe it's located up under the dash, more-or-less in the vicinity of the turn signal control module and a pair of green connectors (also not to be connected together).

Start into it, and get back to us with observations, questions, or perhaps with the solution.
 

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Discussion Starter #3
Thanks for the quick reply.

Are the power windows and power seats working now? (They share a slow blow fuse in the main fuse box in the engine compartment, and a circuit breaker. The fuse is SBF-6, 30 Amps.)[\QUOTE]

No windows working yet, but I will re-check the fuse tonight to see.

From fuse #12, the power goes to FB-26 and FB-27. (These are just identifiers of circuits -- a way to move from page to page in the wiring diagrams without having to draw lines all the way.)

Fuse #12 provides power not only to the combination meter back lighting (through FB-27), but also the lights in most of the dash panel controls and switches. (See page WI-148). So, presumably, all of these lights are not working as well.
I'm unable to look up the pages of the schematics by the WI number, do you happen to have a different page identifier to look it up by? Where I'm getting the schematics I can look them up by circuit function or by the big bold number references, but I can't look them up sequentially.

Thanks for the advice on where to start and what to look for. This is a huge help! I'll report back with new findings, I'm hoping to get windows working sometime this weekend.

-Jon
 

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Pages WI-16 to WI-22 are the "Power Supply Routing" section. This is the section that deals with the fuse panels, fuses, and where they go. It might be identified as section 4 in your system.

WI-148 is in the "Clearance Light and Illumination Light System" section (WI-145 to WI-151). It might be section 26.
 

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Discussion Starter #5
Pages WI-16 to WI-22 are the "Power Supply Routing" section. This is the section that deals with the fuse panels, fuses, and where they go. It might be identified as section 4 in your system.

WI-148 is in the "Clearance Light and Illumination Light System" section (WI-145 to WI-151). It might be section 26.
OK, I've got a better feel for how to read the schematics, but it's still real confusing to find the plugs I'm looking for.

Unfortunately I'm having trouble tracking down which part of the FB-26/FB-27 connector is grounded as it seems to go everywhere. I'm only able to break the connection when I disconnect the main plugs to the fusebox (I5 & B51). From there I'm lost.

I'm having trouble as well tracking down the problem with the window circuit. The fuse appears to be grounded when I turn on ignition, but as far as I can tell all the fuses and relays are working correctly.

Any other broad ideas? If nothing else I'll pull the dash again tomorrow to get a better look at the wiring behind the scenes that I can't see as well from under the steering wheel.

-Jon
 

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Discussion Starter #7
So, after pulling the dash I found one of the grounding issues I was having. This was to the right of the glove box in the dash plastics plugged into a two prong plug in the middle of a wiring harness. It's about the size of a cigarette lighter and a google search of the part number/serial number on the side turned up nothing. Anybody know what this is?

IMG_20130414_120206.jpg IMG_20130414_120218.jpg

I'm not sure why it was plugged in except that maybe it was in a convenient spot and I inadvertantly reconnected it after finishing the core swap. It has zero ohms when hooked up to an ohmeter and was plugged into either the same wire as FB-26 or FB-27 (connected to the downstream side of Fuse 12).

More digging before I replace the dash...

-Jon
 

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Can you provide more details about the connector it was plugged into?

If it measures zero Ohms, then it could well have been shorting a power line to ground. That would depend on what the connector was for.

I presume from what you said that the ground problem at fuse #12 has been fixed with the device removed. Correct?
 

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Discussion Starter #9
Can you provide more details about the connector it was plugged into?

If it measures zero Ohms, then it could well have been shorting a power line to ground. That would depend on what the connector was for.

I presume from what you said that the ground problem at fuse #12 has been fixed with the device removed. Correct?
Ok, just got back from the auto parts store, had to pick up some new fuses. The connector is in the middle of a wiring harness coming out of the base of the passenger side A-pillar. It's a two conductor plug and might i23 (Glove box light)?

Looks like the illumination circuit (Fuse 12) is back to working after removing the offending gadget. Looks like this solves this problem.

Now to solve the window/seat circuit. How likely is it that the circuit breaker is non-operable? I'll start probing the window circuits.

-Jon
 

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The circuit breaker can fail, but it's not likely.

Check SBF-6 for continuity. (If it's good, the keyless entry, including the "horn" that beeps when locking and unlocking, should work.)

If SBF-6 is good, then the areas to check are in the "Power Window System" schematic (section 38).

Check that F/B fuse #18 is good -- it powers the energizing coil in the Power Window Relay.

(If the windows were working before, it's unlikely the relay has gone bad but this can't be ruled out completely.)

What color was that two conductor plug, and do you know the colors of the two wires going to it? (Only importance to this now is in case it should be connected to something more important than the glove box light.)
 

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Discussion Starter #11
Good news, the window circuit is working now. It took me a while but I found B41 plugged into the wrong connector. I'm glad that this didn't cause more problems, but it appears that the object from the picture above is a circuit breaker. I plugged it into B41 and things are working.

I know for a fact that the drivers window and the pass rear window work, but the other two didn't work right away. I'll have to check on this later but the driver's window working is a huge help.

I'll have to start reassembling things for now, but will get back to this later tonight.

Thanks plain OM for keeping with me on this. I've certainly learned a few lessons in car repair, first and foremost being keep track of what you unplug and plug back in (and be extra sure your helpers do the same).

-Jon
 

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Good news.

Here's a diagram of where, roughly, the circuit breaker should be (http://opposedforces.com/parts/legacy/us_b12/type_21/electronic/power_window_equipment/). It sort of looks like the white piece in the photos above.

By the way, this website can be handy when troubleshooting as well as when looking for part numbers.

All the window switches and motors are powered from the same source that you've now resolved, so it might again be connectors not connected or mis-connected.
 
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