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Lighting Fuse?

8K views 7 replies 4 participants last post by  rlouie 
#1 ·
In brief-
Our 2013 Crosstrek's Tail lights work intermittently for a few weeks then blow lighting fuse in the engine bay.
At about the same time the Highbeams go quite dim and the center console lights aren't back lit.
Dealer diagnosed it as clock spring issue and replaces it. Problem is not solved.
We speak at length with the mechanic and he says he needs more time to diagnose. Also notes that the lighting circuit (15 amp in the engine bay) kept popping. But did not pop a 20amp. He also says that there is no diagram for the electrical in this model/year.
Pulls BIU from another car and installs it. Nothing changes.
Dealer then says the wiring harnesses needs replaced. We disagree and take the car home. Now the turn signals and head lights are not working but all other electrical systems work as far as I can tell.
I find that the circuit in question has a 20 amp fuse installed when it calls for a 15 amp.
Also find the engine ground strap to be holding on by a thread and replace it. Placed the battery on a charger and ordered a multimeter to inform my testing.

Does anyone have an electrical schematic for a 2013 crosstrek? Do they exist?
What is downstream of the lighting fuse (15 amp in the engine bay)?
Is there module that would control the components in question ie. Body integrated unit?
Is the dealer/mechanic competent?

Below is the statement of diag the dealer wrote
"Technician tested combination light switch, roll connector. All relays and fuses, and inspected multiple harnesses, as well as tested all bulbs to find where short is in harness. When testing clock spring (roll connector), resistance tests were found to be out of specifications on all terminals. After replacing clock spring and combination light switch, fuse for interior light stopped blowing, but other problems still existed and kept changing. For diagnostic purposes, replaced both fuse boxes with known good ones from another car. No change. Continued testing. Found that with power to fuse, relay is not activating. Swapped with known good relays. No change. Inspected all visible areas of wiring harness for chafing, kinks, chewed wires, etc. non found. Rechecked switch and clock spring, test good. In order to properly diagnose, vehicle would have to have most of vehicle disassembled, including interior, to pierce wires and test where power ends in order to find short in wiring. In summary, fuses ok, relays ok, switches ok, concern is within wiring harness. It is likely that the fuse will pop again, and the switch and or clock spring could again be damaged if the affected area of the wiring harness comes back into a short to ground contact and surges voltage through system, but at this time the components are testing okay, but lights still not working."
 
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#2 ·
First off - Welcome to the forum!

Next, instead of a multimeter to test the battery, I would get a battery conductance tester (pretty cheap these days) for testing the battery as it will not only tell you the voltage but will also tell you the CCA as well as the internal resistance of the battery.

As to your mechanic, they should know better not to put in a large current fuse than what comes from the factory unless they know that circuit can handle it. So, I would take that as an indication that the dealer may not be too competent.

As for a wiring diagram for the MY13, it does exist and is in the factory service manual. To add insult to injury, the MY14 and MY 12 are basically identical to the MY13 when it comes to the electrical diagrams. But back to your question - downstream from the lighting fuse (No 15 - 15A) is the Tail and Illumination relay which is triggered by the BIU. The relay is connected to two other fuses in your passenger compartment fuse box - No 16 7.5A (dash) and No 14 15A (tail lights) - which will power things like the CVT select lever lights, steering wheel lights, dash switch lights (A/C control panel, radio, glove box lights...).
 
#5 ·
Hello and welcome.

I hope you figure out something quickly. Electrical issues truly are a PITA.

As for a wiring diagram for the MY13, it does exist and is in the factory service manual. To add insult to injury, the MY14 and MY 12 are basically identical to the MY13 when it comes to the electrical diagrams.
Just curious as to how accurate is the service manual at http://www.sucross.com/subaru_crosstrek_service_manual-728.html, in relation to 13-17’ models.
While not awesome for the 18’+, I refer to it periodically. I find it useful as an indication tool and sort out the details when I’ve exposed something of interest.
 
#3 ·
Here's the service manual download I got last week:

I can't say that the wiring diagram is the easiest thing to read. I've been kinda skimming through things. There's like a folder of full wiring diagram stuff, but then you might also find bits you need in the other folders for whatever particular items you are looking for.
I'm by no means an expert on it, but I was looking for info on the heated portion of the mirrors, and pretty sure I found some info in one folder like in the glass section for the mirrors, but then more somewhere in the wiring sections... Which more or less makes sense,and I did understand it better, but it stll felt like I had to track things down in multiple places compared to like the wiring diagram I had for my old TR7's...

Does anyone have an electrical schematic for a 2013 crosstrek? Do they exist?
 
#4 ·
Thanks for the insights. I was going to check amps at lighting fuse and subsequent related fuses downstream to see where the power supply stops. Have my hands on a FSM now and its super helpful. Nicely done. I'm stumbling through this now but learning by doing is the best way to accumulate knowledge. Will be diagnosing circuit/relay integrity asap but life has me buried so it could take a couple of days.
 
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