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Guest Message by DevFuse
 

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1985 Subaru GL Wagon - Electrical Problem, keep blowing out a 15 amp fuse for the Brake Lights, Dome Light, and Map Lights

electrical hot wiring short circuit brake lights dont work 15 amp fuse

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14 replies to this topic

#1 chipmunk34

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Posted 30 August 2013 - 06:25 PM

Hello,

Is this a common problem with a common fix?  Does anyone know the reason for this?  The 15 amp fuse that

keeps blowing out is for ECC, Room, Stop.    Stop is the brakes, Room is the interior, so what is ECC?

I thought to look at the brake pedal switch, but dont know where it is.



#2 john in KY

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Posted 30 August 2013 - 09:21 PM

Top of the brake pedal I would guess. 



#3 jono

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Posted 31 August 2013 - 05:04 PM

Got a towbar with electrical connector? They can cause grief if worn against body or get mud or moisture in htere ...



#4 Cougar

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Posted 01 September 2013 - 01:49 PM

If the fuse doesn't blow out until you press the brake pedal then the trouble is with the brake light circuit. If it blows without stepping on the brake then something else is causing the trouble. The ECC is the engine control computer but I doubt it is causing the problem though it is possible. If there is a wire harness for a trailer that is a logical trouble area. If the brake circuit is causing trouble check for shorted wiring inside the sockets for the bulbs. Isolating the connections and replacing them one at a time will show up the bad one if that is the case.



#5 NorthWet

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Posted 01 September 2013 - 03:45 PM

With a wagon, you have the added stress points of wiring passing through to the hatch, plus the wiring in the hatch itself having known issues (i.e. - the defroster cabling has a connector that tends to fry itself, partially because the cabling is stretched a little).



#6 chipmunk34

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Posted 02 September 2013 - 10:20 AM

Thanks for the posts,

The problem I have is this:  When I put the new 15 amp fuse in,it immediatly blows out! 

So the circuit must be staying open - HOT somewhere.  I put a fuse in and watched the interior light flicker for a split second.

I found the brakelight switch, I doubt that it's faulty.  So, like Cougar mentioned, maybe the ECC is the problem?  Anyone know

where the ECC is located?   

 

I hope to get the brake lights working real soon, I have made little progress in pinpointing this problem.



#7 Cougar

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Posted 02 September 2013 - 11:37 AM

The circuit is directly shorted between the power supply, which is the opposite condition of an open circuit. Since the brake light circuit is switched on that means that it is not causing the trouble unless the brake switch is bad and that is doubtful. Some folks have had problems for the lights up in the roof area. To verify the ECC isn't the cause of the trouble you can disconnect it to see if the trouble clears. It should be above the steering column and is a rectangular box. 

 

You would be wise in getting the factory service manual for the wiring on this vehicle to help you locate the problem. It will show you how things are wired and where to locate connections in the car. Ebay is a good place to find one. It would also be helpful I think if you made a test light using a brake light and a bad fuse. By soldering the two lamp wires to each side of the fuse you can insert the old fuse in the fuse panel and the light should turn on bright due to the short on the line. The resistance of the lamp will keep the current flow to the short to a safe level so the wiring won't get damaged. When you find the short and disconnect it then the test light will go dim or turn off. This will save you from blowing a lot of fuses. You can also use an ohmmeter to checked the resistance to ground on the PROTECTED side of the fuse panel, not the power side. The resistance will be very little due to the short until it is removed. As a guess I would think the trouble may be in the roof area. Since disconnecting the ECC is pretty easy I would start with that just to verify it.



#8 MilesFox

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Posted 02 September 2013 - 08:48 PM

Maybe one of the door switches for the dome light is shorted to ground.



#9 jono

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Posted 03 September 2013 - 04:03 AM

was just thinking same - those door switches can be tricky, tricky to work out how they work - I have blown a fuse by trying to extracate the switch with door open - ZAP ! The do have a connector further inside the panels - can be tricky to access.

On second thoughts, maybe the EA81's had power running in door switches....


Edited by jono, 03 September 2013 - 05:34 PM.


#10 Cougar

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Posted 03 September 2013 - 09:21 AM

Well the door switches just switch a ground connection so if one of the wires to the switch was shorted to ground all it would do is keep the dome light turned on. If there is a problem in that area it has to be in the power supply wire to the dome light.



#11 ivans imports

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Posted 03 September 2013 - 10:10 AM

Ecc electic control carberator is the metering soiliniod inside the carb probly shorted or wires rubbed on carb or choke curcit.



#12 Cougar

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Posted 03 September 2013 - 02:54 PM

That's some good info Ivans Imports. I thought that ECC was for the computer. I'll bet you are correct about the choke and that is what is causing the short.



#13 chipmunk34

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Posted 11 September 2013 - 07:04 PM

I solved the problem.  My EGR light came on around the same time that the 15 amp fuse was staying Hot.  I reset the EGR light by

unplugging the blue wire way above the fuse box, and then plugging in the green wire (dangling right next to the blue wire) which resets the EGR light to go on in another 60,000 miles.  After doing this I thought why not try the 15 amp fuse again. I put the fuse in and dome light came on, Map lights worked and Brake lights worked!

 

One thing I would recommend would be a set of circuit breakers 15 amp, 20 amp, etc., they are cheap (Less than $5.00) and it will

allow you to check each light on the circuit that keeps blowing.  The circuit breaker will blow when too hot, then reconnect when it cools down.

Great addition to have in your tool box for electrical problems.  Also check all the fuses with a voltmeter.

 

Thanks everyone for your help!



#14 Cougar

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Posted 13 September 2013 - 10:08 PM

Well I don't know how doing what you did changed things. This trouble might come back again but hopefully it stays away. Thanks for the update.



#15 Gloyale

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Posted 14 September 2013 - 10:27 AM

stands for Engine Control Computer

 

Runs, choke  on 49 state carbed cars, and feedback ECU on CA carbed cars.

 

there are 2 fuses labeled this way.

 

On says ECC ( B ) which is constant 12v

 

and on says ECC (IG) which is the switched power to the FPCU, or CPU, whichever the car has.


Edited by Gloyale, 14 September 2013 - 10:30 AM.






Also tagged with one or more of these keywords: electrical, hot, wiring, short circuit, brake lights dont work, 15 amp fuse

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