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Wax54

Horn/Hazard/Clock fuse blew car won't start need help finding short

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TL;DR

No Start

Starter turns 

No spark

Fuse 5 blew and apparently is super important to the car starting. Can't find any wiring diagram anywhere that has details about this circuit and how it relates to the ECU. 

Need some help with suggestions on where to look for this short. 

 

My journey started about a month ago on Christmas when my recently purchased 1988 Subaru GL died on me in flight as I turned right off a freeway turnpike. I coasted to a stop and after swearing at the air for a few seconds got to work diagnosing my problem. I checked to see if there was spark, no. I checked to make sure the rotor was spining and it was so i knew the timing belt was good. Finally, after a janky self tow up a long hill that ended up costing me my jumper cables and a couple weeks of depressed staring at my engine bay hoping for a sign of life. I finally found out that the Hazard/Horn/clock fuse also is needed for the car to run. This fuse is what blew when the car died and I noticed the hazards weren't working but didn't know if they ever had (new car to me) and figured I had bigger fish to fry. I replaced the fuse and it blew immedieatly. I cannot find a diagram anywhere that seems to accurately represent this fuse. I am currently tearing into this car to find the short, but any advice on where to look would be helpful. I know it is not the horn because I isolated those wires (two green ones that split off pretty early after the fuse box) and got the horns working. now there is one white wire that I can't tell where it goes. Please help...

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check fusible links

any custom wiring that has ever been touched by someone since the car left the dealer lot in 1988 needs to be checked.  aftermarket stereo, head light/foglight upgrades. 

is there any spark out of the ignition coil?

is the ECU LED flashing any check engine light codes?

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See if the fuse blows w/the ignition relay unplugged.If OK,then see what happens w/the relay plugged in and the ECU unplugged.

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Thanks for the responses so fast! Fusible links are all good. There is no stereo, just a bunch of wires hanging there( which I had hoped would be the problem, but I made sure none of them were touching metal or eachother and it still shorts. The coil sparks on it's own, but isn't getting any signal (the bracket is grounded). I then checked the CAS and saw it wasn't getting power so no wonder there is no signal. no lights flashing on the ECU at all. Yes SPFI. And if this seemingly simple fuse actually runs the computer, that's probably why the CAS is not getting power! and Jesus, I have been searching for that diagram on page 52 for the last week, I knew it had to be out there, but never could quite find it. Thank you! I will check on it tomorrow and report back!

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Of course when I think I cant find anything more about my problem and decide to post, I find it is already posted HERE . Any idea which wire in the stereo cluster connects through this fuse so I can triple check it's not touching anything it should't be? 

THANKS A BUNCH!

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Is there power to the fuse at #5?  I guess there would have to be for it to be blowing.

Does it blow instanlty or once the key is "on"  

Try unpluggin the horns.  

IIRC, it's  blue wire with red stripe that is 12v+ to stereo memory.  If it's not that it's the green with a single pole connector.  My EA82 knowledge is fading from memory and I'm not by my books now.

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Fuse 5 does have power. And it shorts even when the key is off. I wired power right into pin 27 of the ecu and the ignition relay from fuse 5 and got the car to start. And run, so now I'll be able to trace down the short when I get the time. Those radio wires definitely aren't touching anything. I was able to isolate the horn and get that back up(the break off that goes to the horn was really close to the fuse box). I suspect it's in the chime circuit which I saw may be a part of this fuse. But for now I have a running car, a horn, no hazard lights, no key warning chime, and (if I ever decide to put a stereo in), no stereo memory. I'm pretty happy. 

 

I'll update as I figure more things out to help future searchers. Thank you all!

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20 hours ago, Wax54 said:

Fuse 5 does have power. And it shorts even when the key is off. I wired power right into pin 27 of the ecu and the ignition relay from fuse 5 and got the car to start. And run, so now I'll be able to trace down the short when I get the time. Those radio wires definitely aren't touching anything. I was able to isolate the horn and get that back up(the break off that goes to the horn was really close to the fuse box). I suspect it's in the chime circuit which I saw may be a part of this fuse. But for now I have a running car, a horn, no hazard lights, no key warning chime, and (if I ever decide to put a stereo in), no stereo memory. I'm pretty happy. 

 

I'll update as I figure more things out to help future searchers. Thank you all!

Good work.Congratulations!

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So I put everything back together, started it up, heard a weird buzzing for a couple seconds but the car started fine. Drove off, and later discovered I didn't have turn signals or power windows. These definitely worked while I was working on the car. Fuse number 10 blew. I checked the resistance to ground and it was about a hundred ohms, so I put a new fuse in. When I turn the car to on (with engine off) the buzzing sound happen again for a few seconds and the fuse has blown again. I unplug the hazard light switch and there is no change in resistance. Could this be caused by a damaged flasher canister when I was putting everything away? Why is the canister beginning power even with the turn signal in neutral position in the hazard lights off? When I turn the hazard lights on while the car is running, the buzzing sound happens and the rear hatch open signal (the instrument panel one) comes on faintly even though the hazard circuit shouldn't be getting any power... Any ideas? Does the strange long four pin unit that gets booked in on the same bracket as the ECU (not the wiper time) have to do with the power windows?

 

Haha, thanks!

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I found if all my indicator bulbs ...maybe not if...after an alternator spike or surge blew the bejesus out of my 85 GLTA electrics I hit my hazards then later found all bulbs for indicators fried - blasted filament to stick to inside of glass

The indicator switch in column buzzed. Found all bulbs dead and as I replaced one by one and checked the buzz turned to a tick tick to perfect when all bulbs replaced

 

85 86 models do not use a relay device to blink...is some weird but clever method inside combo switch

What year is yours?

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Hey! Sorry it took so long to respond, work has had me busy. The one I'm working on is an 88. I took it all apart again and the turn signals started working after I loosened the plastic bracket that holds the 4 canisters (flasher units) and flasher relay. I took it all the way off and Noticed one of the wires going into the relay was a little frayed from being squished against the metal ECU bracket and I think that was shorting it to ground causeing the problem. Put a little tape on and now it's all working fine.

One weird thing though is the back gate open indicated on the dash flashes dimly whenever a door is open. Very weird. But doesn't seem to be causing any problems, just a minor annoyance.

Thanks !

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2 hours ago, Wax54 said:

Hey! ....one I'm working on is an 88. I took it all apart again and the turn signals started working after I loosened the plastic bracket that holds the 4 canisters (flasher units) and flasher relay. I took it all the way off and Noticed one of the wires going into the relay was a little frayed from being squished against the metal ECU bracket and I think that was shorting it to ground causeing the problem. Put a little tape on and now it's all working fine.

Thanks !

Those aren't flashers, they are relays to the electronics in the car.  

IIRC, they are Blower motor, Left and Right Headlight, and Defrost.  

They should definitely be secured away from contact with metal.  

  • Thanks 1

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